Keywords Flashcards
1
Q
accuracy
A
A set of measurements is accurate if there is only a small systematic uncertainty associated with them. A systematic uncertainty is due to a systematic error which affects each measurement taken in the same way. A representation of the degree of similarity between the true value of a given parameter and a measurement of that parameter.
2
Q
exponent
A
also known as the index of power, an expoent is a symbol or number placed above and after another symbol or number to denote the power to which the latter is to be raised.
3
Q
magnitude
A
the numerical value of a quantity. magnitude does not take account of any direction associated with the quantity or of whether the quantity has a positive or negative value.
4
Q
order of magnitude
A
the approximate value of a numerical quantity expressed as the nearest power of ten.
5
Q
power of 10
A
A notation for representing a number as a larger or a smaller number multiplied by a power of ten. For example, in powers of ten notation, 1.234 can be written as 1.234 × 10^3 or 12.34 × 10^2 or 0.123 4 × 10^4 or 123 400 × 10^−2. When the decimal number is below 10, but greater than or equal to 1, for example, 1.234 × 10^3, then this is also known as scientific notation.
6
Q
precision
A
a measurement has a high precision if the random uncertainty associated with it is small. a series of high precision measurements will only show a small scatter; low precision measurements will show a larger scatter in the measured values.
7
Q
prefixes (for units)
A
a unit prefix is a specifier that immediately precedes and is joined to units of measurement to indicate multiples or fractions of the units, eg kilometre, 100 metres.
8
Q
scale
A
a set of divisions used for measurements, as on a ruler. scales are used on the axes of a graph to allow data to be plotted at points corresponding to specific values. for example each cm of the scale on the axis may represent one year, or ten degrees.
9
Q
scientific notation
A
A notation that represents any number by expressing it as a number equal to or greater than 1, but less than 10, multiplied by a power of ten. Thus 1.30 × 10^3 is in scientific notation (because 1.3 is between 1 and 10), but 0.130 × 10^4 and 13.0 × 10^2 are not.
10
Q
significant figures
A
Uncertainties in measurements mean that measured values should be quoted only with a certain number of digits, and this number of digits is known as the number of significant figures. For example, 10.2 cm is quoted to three significant figures (abbreviated to 3 sig figs) and this means that there is some uncertainty in the final digit (perhaps the value is 10.3 cm or 10.1 cm) but the other two digits are certain. The larger the number of significant figures quoted for a value, the smaller is the uncertainty in that value
11
Q
si units
A
An abbreviation for the Système Internationale d’Unités (International System of Units). SI units are used by scientists all over the world to make measurements according to agreed standards. Examples of SI units are the kilogram for mass, the metre for length, and the second for time.
12
Q
bed
A
a layer of sedimentary rock within the earth’s crust (the plural, beds, is synonymous with strata)
13
Q
bedload
A
sedimentary grains that are transported by rolling along the bed of a river etc by flowing water or air.
14
Q
cementation
A
the process of mineral growth in the spaces between the grains of a sediment or sedimentary rock. the resulting cement (commonly quartz or calcite) holds the grains together. cementation is very effective in lithification of sandstones.
15
Q
chemical weathering
A
the breakdown of rocks at the earths surface by the chemical action of acidic waters, eg the dissolution of limestones and the decomposition of feldspars to clay minerals. contrast physical weathering.
16
Q
cleavage
A
(in rocks) the property of a rock that enables it to split along parallel, planar surfaces. it is developed by the alignment of mica under pressure during low-grade regional metamorphism.
(in minerals) planes of weakness within a mineral along which it tends to break. the planes are related to the arrangement of atoms in the minerals structure.
17
Q
contact metamorphism
A
the metamorphism of rocks baked at their contact with a body of magma. affected zones of rock are narrow or localized in extent and occur at relatively shallow depth. contrast regional metamorphism.
18
Q
crystal
A
a solid with a definite geometric form reflecting the regular arrangements of its constituent atoms.
19
Q
deposition
A
(earth science): the buildup of sediment which occurs on a surface when sediment can no longer be carried, either in solution or as solid grains that are in suspension or part of the bedload.
(chemistry): the direct conversion of a gas (vapour) into a solid without passage through a liquid phase.
20
Q
dissolved load
A
material formed by chemical weathering of rocks and carried within a river, stream, lake, sea, etc as dissolved chemicals.
21
Q
dyke
A
a narrow vertical sheet of igneous rock which has been intruded into older rocks
22
Q
erosion
A
the wearing away of the earth’s surface by the mechanical removal of rock and mineral fragments due to action of flowing water, ice, or wind, and the abrasive action of moving debris or glaciers.
23
Q
evaporite
A
a sedimentary rock formed in hot climates by evaporation of salty water to precipitate salts such as the minerals halite (common salt) and gypsum. evaporites may form in enclosed coastal settings.
24
Q
foliation
A
the layering in metamorphic rocks formed by banding of minerals or the parallel alignment of platy minerals. a characteristic texture of regionally metamorphosed rocks that is caused by pressure during deformation.
25
fossil
any evidence of ancient life, usually preserved in sedimentary rocks
26
fragmental texture
the characteristic appearance of a rock composed of broken fragments of various materials.
27
igneous rocks
a rock formed by the solidification of molten rock material.
28
limestone
a sedimentary, composed largely of calcium carbonate (calcite) that if formed typically by the accumulation on the ocean floor of the shells or skeletal remains of marine organisms.
29
lithification
the collective term for the processes of compaction and chemical change that transform loose sediment into rock.
30
lustre
the surface appearance of a mineral that depends on the way it reflects light. typical terms used to describe a mineral's lustre include: glassy, resinous, metallic.
31
magma
molten (liquid) rock.
32
metamorphic rocks
a rock that has had its texture and/or mineral composition changed by the action of heat and/or pressure (usually both). a metamorphic rock can be derived from a sedimentary rock, and igneous rock, or a pre-existing metamorphic rock. metamorphic rocks have an interlocking crystalline texture and often display some form of mineral banding or alignment.
33
mica
a sheet silicate material found in many igneous, sedimentary and metamorphic rocks. muscovite is a pale-coloured variety (silvery-grey) that contains little iron or magnesium. biotite is a dark-coloured variety (dark brown to black) that contains applicable iron and/or magnesium.
34
mineral
a solid object, formed by natural processes , whose chemical composition lies within narrow limits such that each consituent atom fits together with its neighbours in a regular three-dimensional pattern. because of this, each typ eof mineral forms a crystal with a characteristic shape
35
ore minerals
minerals which contain useful materials in sufficient abundance that it can be economically viable to mine them
36
partial melting
the incomplete melting of a rock, during which the minerals with the lowest melting temperatures produce a liquid with a composition different from that of the original unmelted rock. an important cause of magmatic diversity
37
physical weathering
the mechanical breakdown of rocks into smaller fragments by physical processes at the earths surface such as frost shattering, penetrating roots, thermal expansion and contraction.
38
pluton
a large (km sized or more) body of igneous rock that was intruded into older rocks
39
regional metamorphism
the metamorphism of vast volumes of rock, accompanied by deformation that occurs mainly during mountain building at subduction zones and zones of continental collision. regionally metamorphosed rocks are characterized by minerals that have grown in alignment as a result of deformation pressure.
40
rock cycle
a conceptual system that links the ways in which rocks are continually being created and destroyed by geological processes operating at and below the earths surface.
41
saltation
a form of bedload transport involving sedimentary grains bouncing along the bottom and ricocheting off other grains
42
schist
a metamorphic rock with an appearance dominated by highly reflective, crudely aligned flakes of platy minerals, such as mica. schist is formed by regional metamorphism.
43
sedimentary bedform
the three-dimensional shape of the surface of sedimentary beds, eg ripples or dunes, which relates to the physical conditions under which the sediment has been transported.
44
sedimentary rock
a rock formed from sediment laid down at the earths surface that has subsequently undergone lifithication by processes such as compaction and cementation. sedimentary rocks usually have a fragmental texture, with individual grains cemented together. some other sedimentary rocks are formed by biological processes (eg coral reefs) or chemical processes (eg evaporites)
45
silicate minerals
minerals that contain silicon and oxygen
46
sill
a narrow horizontal sheet of igneous rock that has been intruded into older rocks
47
slate
A fine-grained metamorphic rock that breaks along smooth, flat, parallel surfaces. Slate is formed by metamorphism at relatively low temperature and pressure of fine-grained, clay-rich sediments. The platy metamorphic minerals in slate (e.g. mica) grow in parallel alignment from clay minerals in response to pressure during deformation.
48
sorting (of sediments)
A measure of the range of grain sizes present in a sediment or a sedimentary rock. If many grains fall within a narrow range of sizes, the sediment is said to be well sorted. If a wide range of grain sizes is present, a sediment is said to be poorly sorted. The degree of sorting can help to indicate the environment in which a sediment was deposited.
49
strata
Layers of sedimentary rock. (The singular, stratum, is synonymous with bed.)
50
suspended load
Sedimentary grains that are transported within flowing water or air, rather than by moving along the sedimentray bed (bedload).
51
texture
(Of a rock) The description of the particles a rock is made from and of the relationship between them. Texture can be fragmental, when individual mineral grains or rock fragments are cemented together (as in a sedimentary rock) or crystalline, where minerals have grown together so that one crystal interlocks with another (as in an igneous rock or a metamorphic rock).
52
transportation
The movement of sedimentary material in flowing water, air or ice.
53
weathering
The degradation of rocks due to physical, chemical or biological action.
54
ammonite
A member of an extinct group of marine molluscs with a chambered, spiral shell. Ammonites were confined to the Mesozoic.
55
background radiation
The naturally occurring level of radioactivity at any location.
56
basalt
A dark-coloured, fine-grained igneous rock, formed as a result of the rapid cooling of mafic magma at the Earth’s surface. Basalt and its intrusive equivalent, gabbro, are the principal components of the oceanic crust. It contains the minerals pyroxene, plagioclase feldspar, and sometimes olivine.
57
best-fit curve
A curve, or line, drawn on a graph of data on a graph so as to give the best representation of the data as a whole. It need not necessarily go through any of the data points and is drawn in such a way that there are approximately the same number of data points above and below the line.
58
bivalve
A member of a class of molluscs that has a shell with two valves. In most bivalves, one valve is the mirror image of the other.
59
brachiopods
Members of the group of marine animals possessing a shell with two valves of dissimilar shape and size. Brachiopods were much more abundant in the Palaeozoic and Mesozoic than today.
60
corals
Members of a group of marine animals which secrete a calcium carbonate skeleton below anemone-like soft tissue.
61
daughter isotope
An isotope produced by the radioactive decay of another isotope (the parent isotope).
62
echinoderms
A type of entirely marine animals with skeletons composed of many interlocking calcite plates. Among echinoderm groups are sea-urchins (echinoids), crinoids and starfish.
63
eons
The largest unit into which the geological timescale is divided. Earth history consists of two Eons: the Precambrian (or Cryptozoic (hidden life)) and the Phanerozoic (visible life).
64
eras
Major division of geological time, based on fossil characteristics in sedimentary rocks. The Phanerozoic Eon is also divided into three Eras: Palaeozoic, Mesozoic and Cenozoic.
65
fault
A plane along which adjacent rocks have moved.
66
fractional cystallisation
The process by which early-formed crystals become separated from the magma in which they crystallised to leave a magma with different composition. An important cause of magmatic diversity. Compare with partial melting.
67
gabbro
A coarse-grained, intrusive igneous rock, with the same chemical composition as basalt, formed by the slow cooling of basaltic magma at depth within the Earth. Gabbro and its extrusive equivalent, basalt, are the principal components of the oceanic crust.
68
gastropods
Members of the group of animals with an unchambered shell which typically coils in an asymmetrical spiral.
69
granite
A coarse-grained intrusive igneous rock composed largely of interlocking crystals of three types of mineral: quartz, feldspar and mica. It often occurs as large plutons.
70
graptolites
Extinct (Palaeozoic) marine colonial organisms with individuals housed in tiny cups arranged along one or more branches. Their fossils can look at first sight like lines drawn in pencil on a rock, hence the name meaning 'writing on rock'.
71
half-life
The time taken for the number of atoms of a radioactive isotope to be halved by the action of radioactive decay.
72
isotope
An isotope of a given element has the same number of protons, the same number of electrons, but different numbers of neutrons. An isotope is often written as ‘element- mass number’ (for example, lead-235) or, alternatively, the mass number is written as a superscript to the left of the symbol for the chemical element (for example, 235Pb).
73
normal fault
A steeply inclined fault in which the movement has predominantly involved the rocks above the sloping fault plane having moved down, relative to the rocks on the other side of the fault plane. Usually associated with tensional deformation (stretching).
74
nucleus
(Plural: nuclei)
In chemistry and physics, the core of an atom. It contains nearly all of the atomic mass and is positively charged. With the exception of the hydrogen nucleus, which is a single proton, nuclei consist of protons and neutrons.
75
palaentology
The scientific study of fossils.
76
parent isotope
An isotope which undergoes radioactive decay, producing a daughter isotope.
77
periods
Periods Unit of geological time (a subdivision of Era) based largely on the presence of specific fossils in sedimentary rocks. Most geological Periods span several tens of millions of years.
78
principle of fauna succession
The principle that strata contain particular assemblages of fossils in a definite succession, with each stage in this succession representing a particular span of geological time
79
principle of superposition
The principle that, because younger sediments are deposited on older sediments, an individual rock layer is younger than the one beneath it and older than the one above it. Unless the strata have been disturbed or overturned, the oldest layer lies at the bottom.
80
radioactive decay
The spontaneous transformation of one isotope (the parent isotope) into another isotope (the daughter isotope), accompanied by the emission of some energy.
81
radioactivity
The spontaneous transformation of one isotope (the parent isotope) into another isotope (the daughter isotope), accompanied by the emission of some energy.
82
reverse fault
A steeply inclined fault in which the movement has predominantly involved the rocks above the sloping fault plane having moved up, relative to the rocks on the other side of the fault plane. Usually associated with the rocks being compressed sideways.
83
stratigraphic column
The sequence of geological time divisions (Eons, Eras and Periods) arranged in chronological order, with the oldest at the base
84
stratigraphy
The study of strata and their relationships in time and space. Sequences of strata have long been used to establish a generalized geological succession — the stratigraphic column — made up of geological eras and periods, which when given absolute dates forms the geological time-scale.
85
trilobite
A member of an extinct marine group of arthropods confined to the Palaeozoic. Trilobites had an external skeleton, divided lengthways into three lobes, that was shed periodically during growth.
86
unconformity
The absence of strata from a particular time interval in a certain region, due either to non-deposition, or to erosion of any sediment that had been deposited. The term also refers to the actual contact between unconformable rocks. An unconformity is often recognized by a difference in the angle of layering in adjacent sets of strata.
87
uniformitarianism
The concept, fundamental to geology, that geological processes which operate today also operated in the past. It is the basis of the frequently quoted maxim ‘the present is the key to the past’.
88
absolute plate motion
The movement of a tectonic plate relative to a fixed reference point such as a mantle plumes.
89
abyssal plain
The part of the ocean floor that lies between 4 km and 6 km below the surface. Abyssal plains are generally flat and they make up the major part of the ocean floor.
90
active continental margin
A type of convergent plate margin where oceanic lithosphere is subducted beneath a continental margin, such as exists along the west coast of South America. (See also ocean/continent subduction zone.)
91
asthenosphere
A weaker, more easily deformed region of the mantle that is below the lithosphere.
92
bathymetry
The measurement of depth of water in seas, essentially the topography of the seabed.
93
biomodal distribution
A distribution of data that exhibits two distinct peaks (i.e. has two modes).
94
body waves
A seismic wave that travels through the interior of the Earth. There are two types of body wave: a P wave and an S wave.
95
conservative plate boundary
A type of plate boundary where the plates move laterally past each other without convergence or divergence.
96
continental drift
The movement of continents over the surface of the Earth through geological time.
97
convergent plate boundary
A type of tectonic plate boundary where the plates move towards each other, also known as a subduction zone.
98
core
The central part of the Earth, composed mainly of iron. The outer core is liquid, the inner core is solid.
99
cross section
A representation of a vertical slice through the Earth to show an aspect of the subsurface.
100
crust
The upper seismic layer of the Earth. The crust has a relatively low density and low seismic wave speeds. It is about 7 km thick under oceans (oceanic crust), and 20–80 km thick (averaging 35 km) under continents (continental crust).
101
divergent plate boundary
A type of tectonic plate boundary where the plates move apart from one another, also known as a mid-ocean ridge (or spreading centre).
102
earthquake magnitude
A quantitative measure of the size of an earthquake, obtained from the amount of energy released.
103
epicentre
The point on the Earth's surface directly above the focus of an earthquake.
104
focal depth
The depth of the focus of an earthquake below the Earth's surface.
105
focus
The location (point of origin) of an earthquake. This is usually well below the Earth's surface. (Plural = foci)
106
fracture zone
A liner deep sea fault that transects and displaces a mid ocean ridge.
107
full spreading rate
In plate tectonics, the rate at which two points lying either side of an oceanic ridge crest diverge.
108
GPS
Global Positioning System. A system of fixing the location of a point on the Earth's surface with reference to a configuration of satellites.
109
graben
A fault edged, downthrown block of crust that forms a linear valley.
110
half spreading rate
In plate tectonics, the rate at which a single point on one side of a ridge moves away from the oceanic ridge crest.
111
hotspot
A volcanic area above a shallow region of anomalously hot mantle.
112
hotspot track
A chain of active and extinct volcanoes that have formed on a moving plate above a stationary hotspot.
113
hydrothermal circulation
The circulation of hot fluids in the vicinity of a magma body for example at a mid-ocean ridge.
114
hypsometric plot
A histogram showing the relative proportions of the Earth's surface area at different altitudes and depths.
115
inclined seismic belt
An inclined zone of earthquakes (also known as a Wadati Benioff zone) extending several hundred kilometres into the Earth at a subduction zone. A Wadati–Benioff zone defines the position of a cold subducted slab of lithosphere.
116
island arc
The chain of volcanic islands on the overriding plate at a subduction zone where two plates of oceanic lithosphere converge. An island arc lies parallel to an ocean trench. (See also ocean/ocean subduction zone.)
117
lava
Molten igneous rock (magma) that flows over the Earth's surface. The term lava flow can also be used to describe the body of rock formed after the molten lava has cooled and solidified.
118
lithospheric plate
An area of lithosphere, the edges of which are defined by a seismic zone. This is usually abbreviated to plate. Also known as a tectonic plate.
119
mantle
The layer of the Earth between the crust and the core .
120
mantle plume
A localised area of anomalously hot mantle that rises due to buoyancy. Mantle plumes may give rise to hotspots when they melt at shallower levels.
121
mid-ocean ridge
A broad ridge a few thousand kilometres across and 2– 3 km high on the ocean floor, extending for many thousands of kilometres. Mid-ocean ridges do not always lie in the centres of oceans. A mid-ocean ridge is a divergent plate boundary.
122
ocean/continent subduction zone
A type of convergent plate margin where oceanic lithosphere is subducted beneath a continental margin, such as exists along the west coast of South America. (See also ocean/continent subduction zone.)
123
ocean/ocean subduction zone
The chain of volcanic islands on the overriding plate at a subduction zone where two plates of oceanic lithosphere converge. An island arc lies parallel to an ocean trench. (See also island arc.)
124
orogeny
The processes and/or sum of events during which a mountain belt is formed, e.g. the Caledonian Orogeny. An orogeny usually involves the convergence of lithospheric plates, causing folding, faulting, metamorphism and igneous activity. Also referred to as continental collision.
125
plate boundary
The edge of a tectonic plate, where it interacts with a neighbouring plate.
126
plate tectonics
The theory that the Earth's surface is composed of a number of lithospheric plates that can move around. It combines evidence for continental drift with the mechanism of sea-floor spreading, so providing an explanation that links previously unrelated features of the Earth, such as the distribution and shape of mountain belts, the location of seismic zones, volcanism and the shape of the ocean floor.
127
polarity of subduction
The direction of subduction at a convergent plate boundary.
128
pyroclastic flow
A flow of materials from a pyroclastic eruption down the side of a volcano.
129
seismic waves
A wave in the Earth, generated by an earthquake (or an explosion).
130
seismogram
A paper record of ground motion due to a seismic wave recorded by a seismometer. Sometimes referred to as a seismic trace or seismograph.
131
seismology
The study of earthquakes.
132
seismometer
An instrument that measures and records motion of the ground surface.
133
slip
The relative displacement to the two sides of a fault plane which were originally coincident.
134
SONAR
An acoustic survey system which uses the reflection of high frequency sount waves from a surface to image its surface. Frequently deployed from ships to map out the surface of the seabed. (An acronym derived from sound navigation and ranging.
135
subduction
The process by which an oceanic lithospheric plate sinks beneath another plate of either oceanic or continental character.
136
subduction zone
A region of the Earth where oceanic lithosphere subducts (sinks) beneath the edge of another lithospheric plate at a convergent plate boundary.
137
surface waves
A seismic wave that travels at and near the surface of the Earth.
138
s wave (shear wave)
A type of seismic wave; the slower type of body wave. This is a transverse wave in which the rock moves at a right angle to the direction of wave motion.
139
tectonic plates
An area of lithosphere, the edges of which are defined by a seismic zone. This is usually abbreviated to plate. Alo known as a lithospheric plate.
140
topography
Used in this context to describe the range and distribution of elevation of the surface of the Earth.
141
trench (submarine)
An elongate depression on the ocean floor that runs parallel to an active continental margin or to an adjacent chain of volcanic islands (island arc). Oceanic trenches are up to 11km deep, typically 50-100km wide and may be thousands of kilometres long.
142
triangulation
Locating a point with reference to three survey points at a known distance of separation.
143
tsunami
Ocean waves caused by movement of the ocean floor by an earthquake under the ocean. Tsunami can travel great distances across an ocean. They have a small wave height in the deep ocean, but increase in height significantly when they reach a coast, and can be very destructive.
144
vector
An arrow that contains information about direction and magnitude. Vectors of tectonic plate motion show both direction and speed which is normally indicated by length.
145
volcanic ash
Fine (<2mm) solid particulate material erupted from a volcano.
146
volcano
A naturally occurring vent or fissure at the Earth's surface through which molten, solid and gaseous materials erupt.
147
watadi beniof zone
An inclined zone of earthquakes extending several hundred kilometres into the Earth at a subduction zone. A Wadati–Benioff zone defines the position of a cold subducted slab of lithosphere.
148
anthropocene
A proposed epoch relating to significant human impact on the geology and ecosystems on Earth
149
aquifier
Undeground, water-saturated permeable rock or unconsolidated materials
150
assimilation
The conversion of nutriment into a useable form that is incorporated into the tissues and organs or an organism. Examples of assimilation include photosynthesis in plants in which CO2 and water are converted into carbohydrates, or nitrogen fixation by bacteria in which gaseous N2 is converted into ammonia. Animals assimilate food by eating plants or each other.
151
atmosphere
A layer of gases surrounding a planet or other body held in place by the gravity of that body
152
atom
An atom is the smallest constituent unit of matter that has the properties of a chemical element; each chemical element is characterised by a different type of atom. Atoms are roughly 10–10 m across.
153
biogeochemical cycle
A pathway (or pathways) by which a chemical substances moves through both the living (biosphere) and non-living (lithosphere, atmosphere, and hydrosphere) components of Earth. They occur because chemical elements on Earth are recycled, unlike energy.
154
biomass
The amount of living material, usually in some area or volume. If quantified, marine biomass is often expressed in grams of carbon per unit area of sea-surface (or unit area of sea-bed, in the case of benthic ecosystems), i.e. gC m–2. Biomass is also used to refer to the matter of which an individual organism is composed.
155
biosphere
The part of the Earth inhabited by life.
156
carbonate counter pump
A sub-cycle of the carbon cycle, whereby carbon dioxide (CO2) reacts with water to form carbonic acid and bicarbonate. The carbonate pump allows the ocean to take up much more CO2 than if CO2 just dissolved in water
157
carbon cycle
The global transfer of carbon between various carbon reservoirs in the environment, involving both living organisms (biological cycle) and the non-living environment, such as soil, water, rocks and air (geochemical cycle).
158
carbon footprint
The amount of carbon dioxide (or carbon dioxide equivalent for other greenhouse gases) released into the atmosphere as a result a particular acivity.
159
closed system
A physical system in which no matter is exchanged with its surroundings.
160
condensation
The process whereby a substance changes from a gas to a liquid, e.g. water changes from water vapour to liquid water.
161
decomposition
The gradual disintegration of dead organic matter. Some decomposition occurs through physical factors such as wind and water, but it is mostly achieved by bacteria. See detritivore.
162
denitrification
A process, facilitated by microbes, in which nitrate is reduced through a series of intermediate products to ultimately form nitrogen gas (N2)
163
discharge
The flowing of a liquid (or gas) from where it has been confined.
164
eutrophication
The enrichment of an environment, often a water body, with nutrients. It can refer to the enrichment of an environment with excessive amounts of nutrients.
165
evaporation
The process whereby a substance changes from a liquid to a gas, e.g. liquid water evaporates to form water vapour.
166
evotranspiration
The sum of both the evaporation from the soil and other surfaces and transpiration from plants, which describes the process by which water is transferred from land and water surface to the atmosphere.
167
fixation
The process in which a substance is changed from the gaseous or solution phase, into a useable stable form, as in carbon dioxide fixation or nitrogen fixation.
168
flow
The movement of a substance in a continuous stream or current.
169
flux
A process of flowing or change.
170
gas exchange
The biological process by which gases move passively by diffusion across a surface. Gas exchange occurs between the air and cells inside a leaf in plants, and between air and blood in the lungs as examples.
171
hydrosphere
The part of the Earth that includes water, either in or on the surface of the Earth (including the oceans, rivers, lakes, ice), together with water in the atmosphere.
172
lithosphere
The rigid outer layer of the Earth, which includes the crust. It is made up of plates that may be oceanic, continental or both.
173
nitrate
The anion NO3− found in compounds such as sodium nitrate NaNO3 or potassium nitrate (saltpetre) KNO3.
174
nitrification
The aerobic process in which ammonia is oxidised to nitrite and nitrate by the nitrifying bacteria.
175
nitrite
The anion NO2-, found in compounds such as sodium nitrite NaNO2 or potassium nitrite KNO2
176
nitrogen fixation
The conversion of nitrogen gas (N2) into ammonia (NH3) or other nitrogen-containing molecules that can be used by living organisms (the reverse process to dintrification).
177
organic carbon
Carbon in compounds found in living things or the remains of living things. For example, plants produce simple organic carbon compounds through photosynthesis.
178
organic carbon pump
The biologically-driven transformation of carbon dioxide into organic carbon materials, their deposition into deep sea waters and sediments in the ocean, and their decomposition at depth
179
percolation
The process of a liquid slowly passing through a filter or porous material.
180
phases (chemical)
Physically distinctive forms of matter, such as a solid, liquid or gas.
181
photosynthesis
The process whereby plants utilise carbon dioxide, water and light energy from the Sun to manufacture organic compounds (carbohydrates).
182
pool
In a global cycle (e.g. water or carbon), pools provide a means of classifying cycled material by the type of location, irrespective of its real geographical location. For example, pools in the carbon cycle include the plants and fossil fuel deposits.
183
precipitation
A collective term referring to all the forms in which water can fall from the atmosphere onto the Earth’s surface (as rain, snow, sleet or hail).
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pump
In biogeochemical cycles, a pump describes a process which drives fluxes and the name often indicates the main driver of the pump (i.e. a biological pump includes reactions driven by lifeforms).
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reservoir
In a global cycle (e.g. water or carbon), reservoirs provide a means of classifying cycled material by the type of location, irrespective of its real geographical location. For example, reservoirs in the water cycle include the atmosphere, the oceans, ice and snow.
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residence time
The average length of time that a molecule remains in a particular reservoir.
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run-off
Something that drains or flows off, such as rain that flows off land into streams.
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solution pump
Also known as the solubility pump this is the absorption or release of CO2 by water, following changes in solubility of gaseous CO2
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store
In a global cycle (e.g. water or carbon), stores provide a means of classifying cycled material by the type of location, irrespective of its real geographical location. For example, reservoirs in the water cycle include the atmosphere, the oceans, ice and snow.
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system
This is the part of the world in which there is a particular interest. In biology it is often a set of components working together as parts of an interconnecting network. In the context of a chemical reaction, it could simply be the contents of a reaction mixture.
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terrestrial
Related to land or the planet Earth, but also refers to organisms that live on land or processes that occur on land instead of in water.
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water cycle
The continuous circulation of water on Earth between ocean, atmosphere, land, biological organisms, etc. It involves water changing its state between solid (ice), liquid (water), and gas (water vapour).
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autotroph
An organism that makes its own carbon-based material starting with carbon dioxide. An autotroph is also known as a primary producer. Almost all plants are autotrophs; they convert carbon dioxide into carbon based material by photosynthesis.
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carnivores
An organism that obtains its carbon-based materials by consuming living or recently killed animals, either in whole or in part, i.e. a type of heterotroph.
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carrion
The decaying flesh of dead animals.
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commensalism
An association between two species in which one benefits and the other derives neither benefit nor harm.
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community
Considered as a whole, the various populations of organisms (micro-organisms, plants and animals) that inhabit a particular area, and interact together.
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competition
An interaction between organisms or species in which both the organisms or species are harmed. Limited supply of at least one resource (such as food, water, and territory) used by both can be a factor.
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consumers
An organism that cannot manufacture its own carbon-based materials starting from carbon dioxide and therefore feeds on other organisms. Also known as a heterotroph. Compare with producer.
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dcomposers
An organism which breaks down dead organisms through decomposition, including fungi and bacteria.
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detritivores
Animals that feed primarily on detritus, i.e. organic debris from plants and animals.
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ecosystem
All the (interdependent) communities of organisms in a particular geographical area, plus the physical environment that they inhabit.
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ecosystem balance
A state of dynamic equilibrium within an ecosystem in which genetic, species and ecosystem diversity remain relatively stable, subject to gradual changes through natural succession.
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food chain
A linear sequence of organisms in which each organism (or group of organisms) is food for the next member in the sequence.
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food web
A schematic representation of the feeding interactions within an ecosystem or community. Food webs contain multiple food chains and one organism can have more than one food source, thereby linking food chains together.
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guild
A guild is any group of species that exploit the same resources, or who exploit different resources in related ways.
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habitat
The physical and biological environment in which an organism lives.
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herbivores
An organism that obtains its carbon-based materials by consuming living plant (or fungal) material, i.e. a type of heterotroph.
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herbivory
The act of eating plants and a herbivore is an animal that eats plants
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heterotroph
An organism that cannot manufacture its own carbon-based materials starting from carbon dioxide and therefore feeds on other organisms. A heterotroph is also known as a consumer. Compare with autotroph.
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individual
A single, separate organism distinguished from others of the same kind.
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mutualism
An association between two species in which both partners confer some benefit.
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omnivores
Organisms which obtain their food from both other animals and plants.
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parasitism
A non-mutual association between species, where one species, the parasite, benefits at the expense of the other, the host, often without killing the host. The parasite is often much smaller than its host.
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population
A group of organisms belonging to the same species which live in a defined place.
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predation
One animal feeding upon another.
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primary consumer
An organism that obtains its carbon-based materials by consuming another organism either whole or in part, either living or dead, and is the first heterotrophic species in a food chain. These organisms consume plant material.
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primary producer
An organism that makes its own carbon-based material, starting from carbon dioxide. A producer is also known as an autotroph. Almost all plants are producers; they convert carbon dioxide into carbon based material by photosynthesis.
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secondary consumers
An organism that obtains its carbon-based materials by consuming another organism either whole or in part, either living or dead, and is the second heterotrophic species in a food chain.
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species
A group of organisms that are similar to one another in appearance and/or behaviour, and that differ in some way from other closely-related groups of organisms. There is usually a significant degree of reproductive isolation between species that reproduce sexually. The species is the level of taxonomic classification immediately below genus. The second part of an organism’s scientific label identifies it as belonging to a particular species within its genus. For example, the domestic cat is uniquely identified by the scientific label Felis catus (which can be abbreviated to F. catus, providing there is no ambiguity) in contrast to other species within the genus Felis, such as the wild cat (F. silvestris).
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thermogenic
Able to produce heat.
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trophic cascade
An ecological phenomenon triggered by the addition or removal of a large part of a trophic level, in which reciprocal changes in the relative populations of other tropic levels occur through a food chain, which often results in dramatic changes in ecosystem structure and nutrient cycling.
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trophic level
The term used to describe ‘feeding’ levels in food chains or in pyramids of numbers, biomass or energy. Each link in a food chain constitutes a trophic level.
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annual plants
Plants with a life cycle that only lasts one year – they grow from seed, bloom, produce seeds and die in one year.
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anthropogenic
Caused by humans
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biome
the community of species which will naturally develop (usually via succession) in an area
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carrying capacity
The theoretical maximum size of a population which an ecosystem can support. This is usually controlled by the resource availability.
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climax community
The stable community of plants and animals which ultimately result from succession in a given environment.
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colonization
The establishment of a new group of species in an area which have moved in from another area
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cyclicity
Oscillating (usually about a fixed mean) at a periodic interval.
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ecosystem services
Benefits and resources provided by the ecosystem
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empirically deprived
Determined by experimentation or observation, rather than purely from theory
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endemic
Native to a certain place.
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environment
The living (plants and animals) and non-living (resources) of an area or location including external conditions (physical climate) which affect life.
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eutrophic
Rich in nutrients (usually used to describe water bodies)
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hypoxic waters
Low oxygen water in which no life survives. Defined as where oxygen is:
<2(mg/L)
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invasive species
A species of plant or animal which has colonised an area it is not endemic to, usually outside of the normal sequence of succession and often introduced by humans.
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logistic growth model
A growth model for a population in which rate of growth decreases as the population approaches a carrying capacity
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mathematical models
A way of describing a real world system using mathematical structures
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nutrients
Chemical elements and compounds which are the fundamental building blocks of living organisms
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oligotrophic
having few or little nutrients (usually used to describe water bodies).
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perennial plants
Any plant that lives for more than two years
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pioneer species
The first species to colonise a bare (lifeless) environment
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planktic organisms
those (often microscopic) organisms that live free floating in the water column and cannot propel themselves against a current.
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primary succession
The process of colonisation of an area from a standing start of bare-Earth. Primary succession will involve a number of different species in sequence, from early pioneer species which need little or no soil to more complex plants which require more ecosystem services, usually in a predictable order.
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proxy
A measurement or indicator which can be used as an indirect estimate of another variable which it is correlated with.
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rarefaction curve
A plot of species number vs. number of individuals sampled, used to estimate species richness and to help choose appropriate sampling strategy.
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red tides
Marine waters turned red by vast blooms of planktic algae (dinoflagellates cause the red colouration). Often caused by eutrophication.
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representative
A representative sample is one which has properties which accurately reflect the properties of the population from which it is taken.
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sample
A subset selected from a defined population.
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secondary succession
The process of colonisation of an area which has been previously populated by plants and animals that have been removed by a disturbance. Secondary succession will involve a number of different species, usually in a predicable order.
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species richness
The number of different species in a population, this population can be a landscape, ecosystem or region.
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succession
The process of progressive replacement of early pioneer species with successive species until a stable climax community is reached.
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absorbance
A measure of the amount of light (of a specified wavelength) absorbed by a substance
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acid rain
Precipitation containing high levels of acidic components typically as a result of atmospheric pollution
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activation energy
The threshold level of energy that a reactant must possess for a specific chemical reaction to occur
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ALARA
(As Low As Reasonably Achievable) - a key principle in the balancing of risk and benefit when evaluating procedural safety.
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ALARP
(As Low as Reasonably Practicable) - a key principle in the balancing of risk and benefit when evaluating procedural safety.
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alpha particle
(α-particle) The particle that is ejected in alpha-decay. An α-particle is a helium nucleus, which is represented as 4/2 HE (or He2+, because it is a helium atom stripped of both of its electrons)
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anemometer
A device used to measure wind speed
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antibiotic
A class of chemical compound that can kill or inhibit the growth of bacteria
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antibiotic resistance
The capacity of bacteria to resist the effects of exposure to antibiotics
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antinbiotics
Plural of antibiotic.
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aseptic
Conditions in which contamination by (typically pathogenic) microorganisms is prevented
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autoclave
A device used to subject solids and liquids to sustained high temperature and pressure for sterilisation
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bacilli
Rod shaped bacteria
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bacteria
A domain consisting of prokaryote organisms; there are two such domains, the other being Archaea
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beaufort scale
Beaufort scale of wind force - scale relates wind speed to specific conditions at sea and/or on land
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beta particle
A fast-moving electron emitted during a particular type of radioactive decay known as β -decay. Being electrons, β-particles carry a negative charge. β-particles are, in fact, only emitted in beta-minus decay. In beta-plus decay a positively charged particle (a positron or antielectron) is emitted instead
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binary fission
A form of asexual reproduction common in prokaryotes in which a single mature cell divides in half to produce two new identical cells
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biore mediation
The use of microorganisms to degrade contaminants/pollutants in a given environment/location
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celcius scale
A scale used for measuring temperature. The normal freezing temperature of water on this scale is defined as 0 °C (zero degrees Celsius) and the normal boiling temperature of water as 100 °C (one hundred degrees Celsius).
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cloud chamber
A particle detecting instrument in which ionising radiation can be visualised
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cocci
Spherical shaped bacteria
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collision theory
Theory that conceptualises chemical reactions as a series of collisions between reactant particles. Used to make qualitative deductions about reactions and reaction rates
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compound leaf
A leaf consisting of a common stalk supporting multiple leaflets
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concentration
A measure of the amount of solute (often a solid) dissolved in a specific volume of solution. Units relate to the mass (g or kg) or number of moles of solute in a volume of solution, e.g. g litre−1 or mol litre−1.
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constant of proportionality
(or proportionality constant) In a directly proportional relationship, the constant factor that expresses how the dependent variable depends upon the independent variable.
If two quantities are proportional to each other, for example y ∝ x, then we can write y = kx, where k is the constant of proportionality.
Multiplying the independent variable by the proportionality constant generates the value of the dependent variable.
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control measure(s)
Action(s) that can be performed to reduce the potential of hazard exposure
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cosmic rays
Source of radiation (high energy particles) originating from beyond Earth's atmosphere
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cumulative
An increase in parameter magnitude due to the successive additive effect of multiple contibuting events
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cuvette
A small tube with a square cross-section open at one end to hold samples for analysis in a spectrophotometer
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deciduous
Denotes a plant/tree/shrub that sheds leaves seasonally
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decline phase
Phase of bacterial growth in which the number of dead/dying cells in a population exceeds the number of new cells being added to the population
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deforestation
Removal of forest (typically rainforest) and conversion of land for non-forest use (typically yielding a less biodiverse ecosystem)
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dependant variable
A measured quantity, the value of which depends on the value chosen for another quantity (the independent variable). On a graph, the dependent variable is plotted on the y axis. For example, if an investigator selected children of certain ages and measured their heights, then height would be the dependent variable.
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diptheria
Highly contagious bacterial infection that affects the upper airway
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DNA
Abbreviation for deoxyribonucleic acid. The class of molecules that carries the genetic information of organisms and is thus the genetic material. DNA is a polymer whose monomers are nucleotides, which consist of three component parts joined by covalent bonds: a phosphate group, a sugar (deoxyribose) and a base. There are four different bases in DNA: adenine (A), guanine (G), cytosine (C) and thymine (T). Nucleotides joined together form polynucleotides. Each DNA molecule consists of two polynucleotide chains intertwined to form a characteristic double helix. DNA molecules are by far the largest known molecules in living organisms; some have relative molecular masses of many billions! DNA carries the genetic information of the cell, coded as a sequence of nucleotides (and hence a sequence of bases).
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DNA mutation
A change in the nucleotide sequence of a piece of DNA
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electromagnetic wave
Manifestation of the transfer of energy associated with electromagnetic radiation. Produced by the interaction of perpendicular electric and magnetic fields.
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evergreen
Denotes a plant/tree/shrub that retains green leaves throughout the year
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exponential
An exponential change is one in which the value of a quantity decreases or increases by the same factor in equal intervals. Thus the shape of the graph obtained by plotting the number of radioactive decays from a sample against time is described as an exponential decay, or a falling exponential since the graph falls by a constant factor of two for every half-life that elapses
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farenheit (scale)
A scale used for measuring temperature. The normal freezing temperature of water on this scale is defined as 32 °F (32 degrees Fahrenheit) and the normal boiling temperature of water as 212 °F (two hundred and twelve degrees Fahrenheit).
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false negative
Case in which a specified condition/outcome/attribute is declared to be absent when it isn't
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false positive
Case in which a specified condition/outcome/attribute is declared to be present when it isn't
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falsifiable
An inherent characteristic of all scientific theories and hypotheses that allows for them to be proven false
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first order reaction
A chemical reaction the rate of which is proportional to the concentration of a given reactant
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foliage
Collection of leaves supported by a plant/tree/shrub
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frequency (wave)
The number of complete cycles of a wave that pass a certain fixed point in a unit of time. Conventionally measured in the SI unit of hertz, Hz (or equivalently s–1). It is equal to one over the period of a wave, f = 1/T , and related to the wavelength λ and speed v of a wave by v = fλ.
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gamma ray
A type of electromagnetic radiation of short wavelength which is commonly emitted during radioactive decay. It is not deflected by a magnetic field, and this distinguishes it from alpha-particles and beta-particles.
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generation time
The time required for the number of bacteria in a population to double
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growth medium
A mixture of substances in liquid, solid, or semi-solid form that can be used to support the growth of microorganisms like bacteria
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hazard
An object/event/process that could potentially cause harm
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histogram
A graphical representation in which the horizontal axis is divided into a set of intervals (usually equal). On each of these intervals a rectangle is constructed with a width equal to the interval, and a height that represents the value of the quantity on the vertical axis that applies at the particular interval. For example, the intervals could be the months in the year, and the vertical axis could be the mean monthly rainfall. Note that there is no gap between the rectangles.
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hypothesis
A tentative explanation, based on the available evidence, which accounts for observations or facts. It may be tested by making further observations, and may be modified in the light of new evidence or observations.
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independent variable
A quantity, the value of which is chosen by the investigator. On a graph, the independent variable is plotted on the x axis. For example, if an investigator selected children of certain ages and measured their heights, then age would be the independent variable, and height the dependent variable
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ionisation
As in ionising
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ionising
Capacity (of radiation) to cause the removal of electron(s) from a molecule/atom to result in the formation of ion(s)
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ionising radiation
A type of radiation which has the capacity to remove one or more electrons from a molecule/atom and results in the formation of an ion/ions.
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lag phase
Phase of bacterial growth in which the population of cells adapts to the environment. This may require the cells to make metabolic changes before optimal growth rates can be achieved
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leaf area index
Ecological parameter representing leaf area per unit ground area. (Also sometimes abbreviated to 'LAI'.)
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linear
Property of a mathematical relationship between two variables/factors that can be represented as a straight line on a graph
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logarithmic increase
Mathematical function that represents the optimum growth of a bacterial population dependent on binary fission
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log phase
Phase of bacterial growth in which the population is able to grow at an optimum rate (logarithmically)
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Luria-Bertani (LB) broth
A commonly used formulation of growth medium for bacteria
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meteorologist/meteorology
A scientist who observes, analyses and makes predictions about the weather/The branch of science focused on the study of the atmosphere and events within it
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microbiological/microbiology
Pertaining to the branch of science specialised in the study of microorganisms (bacteria, viruses, protozoa, funghi and archae)
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modal size class
The most abundant grain size class in a sediment sample
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mode
The most frequent value present in a series of values
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MODIS
Moderate Resolution Imaging Spectroradiometer - a type of instrument carried by the NASA satellites Terra and Aqua that collects data about the Earth's surface
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monsoon
A climate characterised by significant seasonal changes in prevailing wind direction that typically result in large changes in rainfall and distinct 'wet' and 'dry' seasons
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naturally occuring radioactive material
Radioactive substances that are widely distributed in the Earth's crust
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non-ionising
Any radiation that carries insufficient energy to result in the ionisation of any atoms or molecules it is exposed to
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null hypothesis
Formalised statement predicting that there will be no difference between the various groups or conditions being compared in an experiment
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nutrient cycle
The sequence of events and processes that describes how nutrients are removed from the physical environment, transferred to biological systems (organisms) and then returned to the physical environment (recycled)
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parameter
A characteristic that defines a particular system or specifies the range/limits of the operation of a system
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pathogen
A disease-causing organism, including bacteria and viruses, and also parasites, such as tapeworms
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pathogens
The plural of pathogen.
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peer review
The process by which work (typically scientific/technical/academic) of an individual or group of individuals is evaluated by others working in the same or a very similar field
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penicillium notatum
Species of fungus (also known as Penicillium chrysogenum) that produces the antibiotic penicillin
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permeability
A measure of the ease with which fluid can transit through rock
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perpendicularly
At right angles (ninety degrees) to
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petri dish
A shallow glass or plastic dish with a circular cross section and removable lid that is often used to contain growing microorganisms or eukaryotic cells
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porosity
A measure of the amount of open space contained within rock
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post antibiotic era
Era of medicine with no viable antibiotic available.
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PPE
Personal Protective Equipment - any of a range of items that are designed to protect individuals from health and safety hazards
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product
(Of a chemical reaction) The new material (or materials) formed as a result of a chemical reaction.
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prokaryotes
An organism comprising a single cell (with a few exceptions) in which the DNA is not contained within a nucleus. Prokaryotes are members of either the domain Archaea or the domain Bacteria.
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proportional (to)
Two quantities are said to be proportional to each other if, when the value of one is multiplied (or divided) by a certain amount, the value of the other also becomes multiplied (or divided) by the same amount. For example, the cost of petrol is proportional to the volume of petrol bought, so the cost of buying 50 litres of petrol is twice the cost of buying 25 litres of petrol which is five times the cost of buying 5 litres. This is equivalent to the two quantities always having the same ratio. For example, the volume of petrol divided by its cost has the same, constant, value no matter how much petrol is involved. When two quantities x and y are proportional to each other, this can be written as y ∝ x. On a graph of y against x, they would plot as a straight line passing through the origin with gradient equal to y/x. The proportionality y ∝ x can be converted into the equation y = kx by introducing a constant of proportionality k.
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protocol/procedure/method
Detailed sequence of events and actions that must be carried out in order to complete a given process/experiment/investigation
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quanititative
Measurements or data with numbers and units attached to them, for example the number of centimetres of rain per year, are said to be quantitative.
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radiation
Something that spreads out from a source. See also electromagnetic radiation
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radiation sickness
A series of symptoms resulting from a (typically) short duration exposure to a high dose of radiation
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radon
A radioactive element (86Rn). When produced by the radioactive decay of uranium in rocks and the soil it is typically in gaseous form.
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rate constant
A constant of proportionality incorporated into rate equations describing the relationship between the rate of a chemical reaction and the concentration of one of the reactants
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rate equation
An equation that relates the rate of a chemical reaction to the concentration (and sometimes pressure) of the reactants
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reactant
A substance that takes part in a chemical reaction and whose constituent atoms appear in the product(s) of the reaction.
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recombinant
In biology this pertains to a piece of DNA that would not occur naturally and that has had to be made in the laboratory
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risk
The probability that a particular hazard will cause harm such as adverse health effects to anyone exposed to that hazard
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risk assessment
The process by which a planned programme of work is evaluated in terms of the hazards associated with the work and the risk of harm being experienced by individuals (including those involved in the work and others who may be in the vicinity)
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savannah
Type of ecosystem characterised by grassland and trees spaced widely such that the canopy does not close
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second order reaction
A chemical reaction the rate of which is proportional to the squared concentration of a given reactant
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sediment
Material derived from pre-existing rock, from biological sources, or formed by chemical processes, that is deposited at or near the Earth's surface.
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semi-log (or log-linear) plot
A graphical representation in which one axis has a logarithmic scale and one axis has a linear scale
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sorting
A measure of the range of grain sizes present in a sediment or a sedimentary rock. If many grains fall within a narrow range of sizes, the sediment is said to be well sorted. If a wide range of grain sizes is present, a sediment is said to be poorly sorted. The degree of sorting can help to indicate the environment in which a sediment was deposited.
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spectrophotometer
An instrument that measures the amount of light of a specific wavelength that passes through a sample of liquid held in a cuvette
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spirilla
Sprial shaped bacteria (rigid)
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spirochaetes
Spiral shaped bacteria (flexible)
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stationary phase
Phase of bacterial growth in which the number of dead/dying cells in a population equals the number of new cells being added to the population
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statistically significant
An indication of the likelihood that a relationship observed between two groups/conditions is due to random chance
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sterile
Free from microorganisms
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super-saturated
A solution containing more dissolved material than the solvent can support in standard conditions/a vapour with a higher partial pressure than the vapour pressure of the compound
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surface area
The total area enclosed by all the exposed faces of a three dimensional object
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surface processes
The variety of processes that occur on the Earth's surface and that can affect its physical profile, properties, composition and function
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testable
An inherent characteristic of all scientific theories and hypotheses that allows for them to be evaluated by someone other than the originator.
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tetanus
A bacterial infection of the nervous system
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theoretical physics/ theoretical physicist
Theoretical Physics/Theoretical Physicist
A branch of science specialised in the use of mathematical models and conceptual understanding of the laws of the universe to make predictions about and improve the understanding of phenomena in the physical world/A scientist who works in this area
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transpiration/transpire
The giving off of water by the leaves of a plant. Plants draw water from the soil via their roots. This water is carried up through the stems or branches to the leaves, from where it evaporates through stomata. See also evaporation
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tuberculosis
A contagious bacterial infection of the lungs
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tundra
An ecosystem characterised as largely treeless and relatively barren with limited colonisation by low level shrubs and other plants
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turbidity
A measure of the cloudiness (lack of transparency) in a sample of liquid
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typhoid
A contagious bacterial infection that can affect many organs in the body
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uncertainty
An estimate of the likely range of a measured quantity. For example, the length of a piece of string might be quoted as 10.2 cm ± 0.2 cm; here the uncertainty is ± 0.2 cm, which means that the length is likely to be in the range 10.0 cm to 10.4 cm.
At another level, uncertainty can describe the results of a lack of information, or disagreement about what is known (or even what is knowable).
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vapour
A substance in the gas phase
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variable
Any factor that can be changed and measured in an experiment
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vibrios
Comma shaped (curved) bacteria
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zero order reaction
A chemical reaction the rate of which is not dependent on the concentration of a given reactant.
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acceleration
The rate of change of velocity. In SI units acceleration is measured in metres per second per second (m s–2 ). Like velocity, acceleration has a magnitude and a direction associated with it.
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acceleration due to gravity
The acceleration of an object that is falling freely under the influence of a gravitational force. Usually applied to the acceleration of objects close to the Earth's surface, where the acceleration of any freely falling object has the value g = 9.8 m s-2 irrespective of the mass of the object
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balanced force
a force on an object is said to be balanced if it is counteracted by a force of equal magnitude in the opposite direction
381
coefficient of friction
The constant µ in the relation Ffric = µ N between the magnitude Ffric of the maximum frictional force on a body as it slides over a solid surface, and the magnitude N of the normal reaction force that the surface exerts on the body. The value of µ depends on the surfaces involved and their state of lubrication, but is largely independent of other factors, including the area of contact and the speed of the object.
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component
(of a force) The strength of a force along two directions at right angles to one another that can be used to specify a force
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continuous spectrum
A spectrum consisting of light (or other electromagnetic radiation) of all colours (or all photon energies, wavelengths or frequencies). The spectrum of white light from a tungsten filament light bulb is a continuous spectrum. Compare with line spectrum.
384
cosine
The cosine of an angle θ in a right-angled triangle is defined by cos θ = adjacent / hypotenuse, where ‘adjacent’ is the length of the side next to θ and ‘hypotenuse’ is the length of the side opposite the right angle.
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coloumb
In SI units, the unit of electric charge, with the symbol C.
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coulombs law
Two particles of unlike (or like) charge, at rest, will attract (or repel) each other with an electric force that's proportional to the product of the charges divided by the square of their separation.
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dynamic equillibrium
(In the context of forces) An object is in a state of dynamic equilibrium if it is acted upon by balanced forces, but is moving with a constant speed.
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electric charge
A fundamental property of matter. There are two types, positive and negative charge. Like charges repel each other with an electric force, and unlike charges attract each other. Objects with no charge, or with equal amounts of positive and negative charge, are electrically neutral. The SI unit of charge is the coulomb, with the symbol C. The fundamental unit of electric charge is the charge of a proton, represented by +e, which has a value of 1.6 × 10-19 C.
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electric field
The region where electric forces act, produced by an electric charge or by a varying magnetic field. See also Coulomb's law.
390
electric force
The force produced on a charged object by another electric charge. The electric force between two charged objects depends on Coulomb's law.
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electromagnetic interaction
One of the four fundamental interactions. In most situations it is adequately described by Maxwell's laws of electromagnetism. However, by incorporating the effects of quantum physics and Einstein's special theory of relativity, the modern theory of QED provides a better description on very small size scales and in high-energy situations. It explains interactions between particles that possess electric charge in terms of the exchange of quanta called photons. It unifies all electric, magnetic and radiation phenomena into a single theory. Electromagnetic interactions get stronger with increasing energy of interaction.
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equillibrium
For the purpose of this module, an object is said to be in equilibrium if it is acted upon by either no force or balanced forces. Thus, an object in equilibrium remains at rest or moves with a constant speed. See dynamical equilibrium and static equilibrium.
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force
A disturbance that tends to accelerate an object. Forces can negate the effects of other forces, so acceleration will ensue only if an unbalanced force acts on a body. In SI units, the unit of force is the newton (N).
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free-body diagram
A diagram used in the analysis of a set of objects that shows only the object of interest and the forces that act upon it.
395
frictional force
The force that arises when relative motion occurs or is tending to occur between two solid bodies that are in contact. (See coefficient of friction)
396
gradient (of a graph)
The slope of a line on a graph, given by the change in vertical position (the rise) between two points divided by the corresponding change in horizontal position (the run). If the coordinates of two points on a straight line are (x1, y1) and (x2, y2) then the gradient of the graph is: gradient y y x x rise run 2 1 2 1 = = - - (
397
gravity
The natural phenomena that gives rise to a force that causes any object (with mass) to be attracted to any other object (with mass). In colloquial speech, the term is used to describe the attraction of objects on or near the Earth's surface towards the centre of the Earth.
398
magnitude (of a force)
The size of a force
399
mass
The measure of the quantity of matter in an object. In SI units, the unit of mass is the kilogram. The mass of a body determines its acceleration 47 when it is acted on by an unbalanced force; the greater the mass (for a given unbalanced force) the smaller the acceleration. The quantitative relationship is given by Newton's second law of motion F = ma. Mass is also a measure of the inertia of a body. Mass also determines the magnitude of the gravitational force acting on a body. This gravitational force is also known as the weight of the body. Mass and energy are related by Einstein's equation E = mc2.
400
maximum frictional force
The largest frictional force, defined as the product of the coefficient of friction and the normal reaction force.
401
maxwells laws of electromagnetism
A theory unifying the phenomena of electric and magnetic interactions, as they were understood towards the end of the 19th century. The theory explains that stationary electric charges give rise to electric fields, that moving electric charges (i.e. electric currents) give rise to magnetic fields, that a changing magnetic field produces an electric field, and that a changing electric field produces a magnetic field. A prediction of Maxwell's theory was the existence of electromagnetic Glossary 48 radiation which travels through space at the speed of light. Compare with quantum electrodynamics.
402
normal reaction force
When an object rests on (or is pressed into) a solid surface, the solid is compressed slightly. The solid resists compression by exerting a force on the object. This reactive force acts at right-angles to the surface at the point of contact, and is therefore called a normal reaction force.
403
resolving forces
The process of finding a force's components, along specified directions, from the magnitude and direction of the force.
404
sine
The sine of an angle θ in a right-angled triangle is defined by sin θ = opposite / hypotenuse, where 'opposite' is the length of the side opposite θ and 'hypotenuse' is the length of the side opposite the right angle.
405
speed
The rate at which a distance is travelled. In SI units speed is measured in metres per second (m s−1). Note speed is the magnitude of velocity.
406
spring constant
The constant ks that relates the spring force Fstr and the extension x for an ideal spring that obeys Hooke's law; Fstr = −ks x.
407
static equillibrium
(In the context of forces) An object is in a state of static equilibrium if it is acted upon by balanced forces, and is at rest.
408
tension
An object is in a state of tension when a force acts on it in such a way as to increase its length.
409
unbalanced force
A force which is not counteracted by a force of equal magnitude in the opposite direction, and hence causes the acceleration of an object.
410
weight
A physical property that quantifies the strength of the gravitational force acting on a body which has a certain mass. Mass m is related to weight Fg by the equation Fg = mg, where g is the acceleration due to gravity. The term weight is often used colloquially in contexts where the correct scientific term is mass.
411
absolute zero
The lowest temperature that can be attained, 0 K or −273.18°C
412
dynamo
A device that turns mechanical motion into electrical current.
413
heat
The transfer of energy from one object to another that occurs because of a temperature difference between the two. Heat is always transferred from hot to cold.
414
kelvin
The SI unit of temperature, symbol K
415
negative ion
(or anion) An atom or molecule that has gained one or more electrons, and as a result carries a negative charge.
416
positive ion
(or cation) An atom or molecule that has lost one or more electrons, and as a result carries a positive charge.
417
potential difference
When a charge of 1 C is moved from one location to another a potential difference of 1 V, the quantity of work done on the charge is 1 J.
418
potential energy
The energy associated with the presence of a force.
419
power
The rate at which energy is transferred from one thing to another. Power is measured in watts (W), and 1 W is 1 J s−1
420
pressure
A measure of the force per unit area.
421
SI base unit system
In the SI unit system, there are seven base units; all other units can be expressed in terms of the base units. The base units are:
```
Mass - kilogram - kg
Time - second - s
Distance - metre - m
Amount of substance - mole - mol
Electric current - amp - A
Temperature - Kelvin - K
Luminous intensity - Candela - cd
```
422
SI derived unit
An SI derived unit i a unit formed by combining the SI base units (always through multiplication or division of powers of the base units). For example a 1 joule (J) is equivalent to 1 kg m2 s−1.
423
temperature
A measure of the hotness of an object. In SI unit temperature is measured in kelvin (K).
424
thermal energy
The energy associated with temperature. Microscopically, the thermal energy is the sum total of the random (kinetic) energy of the atoms and molecules that comprise a substance.
425
volt
The unit of potential difference. Moving a charge of one coulomb through a potential difference of 1 V.
426
work
The amount of energy transferred from one thing to another by the action of a force. The quantity of work done W (in J) by a force F (in N) applied to move an object through a distance d (m) is W = F × d.
427
atomic number
The number of protons within the nucleus of an atom; it is also equal to the number of electrons in the neutral atom. Each chemical element has a unique, characteristic atomic number.
428
chemical bonding
The means by which atoms are attached to each other. For example, in a water molecule an oxygen atom is attached to each of two hydrogen atoms by chemical bonding.
429
chemical element
A substance that consists of only one type of atom. For example, the chemical element copper is made only of copper atoms. A chemical element cannot be broken down into simpler constituents by using chemical reactions. All the atoms in a sample of a chemical element have the same atomic number.
430
chemical formula
A representation of a chemical substance that uses chemical symbols to denote the constituent atoms, and subscripts to indicate the relative numbers of atoms of each type. For example, water is represented by the formula H2O.
431
conductors
Conductors are materials that allow a transfer of energy. Conductors of electricity allow the flow of charged particles. Conductors of heat allow the transfer of thermal energy.
432
covalent bond
A type of chemical bond in which a pair of electrons are shared between two atoms.
433
diatomic molecule
A covalently bonded molecule containing just two atoms bonded together.
434
ductile
Materials that are easily drawn into wires.
435
electron
(e-) One of the component particles from which an atom is made. Electrons have a negative electric charge, and they surround the atom's positively charged nucleus. Electrons carry the electric current in metals.
436
electron conductor
A material through which an electric current will flow
437
electron configuration
The arrangement of electrons in an atom (or molecule).
438
giant covalent structure
A substance where many atoms are covalently bonded in a regular three-dimensional array, but with no defined size.
439
group
A set of chemical elements, commonly placed in a vertical column in the Periodic Table, having related chemical properties
440
hydrocarbons
Covalent compounds containing atoms of carbon and hydrogen only.
441
ionic interactions
The electrostatic attractive forces between positively charged ions and negatively charged ions.
442
ions
An atom or a molecule or a chemical group that has lost or gained one or more electrons, leaving it with a positive or negative electric charge
443
malleable
Materials that can be beaten into shape.
444
neutron
One of the two types of particle found in the nucleus of an atom. The neutron has zero electric charge and a mass very close to that of the proton. As with the proton therefore, the relative atomic mass of a neutron is very close to unity on the scale of relative atomic masses.
445
noble gases
The gaseous chemical elements helium, neon, argon, krypton, xenon and radon, which are all placed in Group 18 of the Periodic Table. These elements do not readily form chemical compounds with other elements.
446
periodic table
An arrangement of elements which organises them in order of increasing atomic number across several rows known as periods. The vertical groups contain elements with related properties.
447
proton
The nucleus of the hydrogen atom and one of two constituents of all other nuclei; the particle has a relative mass very close to unity on the scale of relative atomic masses. They are positively charged.
448
amplitude
(of a wave) Half the peak-to-trough displacement of a wave
449
de broglie wavelength
The wavelength associated with the propagation of a 'particle' through space. Named for Louis de Broglie, who first suggested that all particles move from place to place with wave-like properties, and so exhibit wave–particle duality.
450
electromagnetic spectrum
The entire range of electromagnetic radiation from radio waves, through microwaves, infrared radiation, light, ultraviolet (UV) radiation, and X-rays to gamma-rays. All electromagnetic radiation propagates as waves with the speed of light c = 3.00 × 108 m s–1, but interacts with matter (i.e. is emitted or absorbed) as a stream of particles, called photons.
451
electronvolt
A unit of energy corresponding to the energy converted when an electron moves from one terminal of a 1 V battery to the other. Numerically it is equal to 1.602 × 10–19J. The energy of photons of light is conveniently expressed in units of electronvolts, but the energy of a fundamental particle is usually expressed in MeV (106eV) or GeV (109eV).
452
excited state
Any quantum state that's not the ground state.
453
exclusion principle
A rule of quantum physics, described by Wolfgang Pauli, which forbids any two electrons in the same atom from occupying the same quantum state.
454
frequency
(of a wave) The number of complete cycles of a wave that pass a certain fixed point in a unit of time. Conventionally measured in the SI unit of hertz, Hz (or, equivalently, s-1). It is equal to one over the period of the wave, f=1/t, and is related to the wavelength λ and the speed of a wave by v = f λ.
455
ground state
The lowest energy arrangements of electrons in an atom (or molecule). The quantum state that corresponds to the lowest energy level of an atom, or other quantum system.
456
heisenberg uncertainty principle
A fundamental result of quantum physics, discovered by Werner Heisenberg, that rules out the possibility of combining definite knowledge of some quantities (such as position) with definite knowledge of certain other quantities (such as velocity). It also limits the precision with which certain quantities can be measured simultaneously.
457
hydrogen-like ions
Any ion which, like hydrogen, has only a single electron bound to its nucleus. Examples include He+, Li2+ and Be3+. The energy levels of hydrogen-like ions resemble those of hydrogen itself, merely scaled in energy by the atomic number squared.
458
indeterminancy
A characteristic feature of quantum physics which refers to the fact that the behaviour of an individual quantum system cannot be predicted in advance, and that the positions, speeds and other attributes of quantum systems cannot be precisely known in combination.
459
interference
The phenomenon arising when two waves meet. Constructive interference is the phenomenon whereby two waves combine to produce a wave with a larger amplitude than either of the original oscillations or waves. Destructive interference is the phenomenon whereby two waves combine to produce a wave with a smaller amplitude than either of the original oscillations or waves.
460
madelung rule
A rule used to determine the approximate order in which orbitals are filled in atoms.
461
magnetic quantum number
A quantum number represented by the symbol mlused when labelling quantum states. It may take values between –l and +l, where l is the orbital quantum number.
462
nanometre
A unit of distance corresponding to 10-9 m. Different colours of visible light have a wavelength of a few hundred nanometres
463
neutrino
A subatomic particle with no charge that interacts weakly with matter
464
newton
In SI units, the newton is the unit of force, symbol N, and is equivalent to kg m s–2 .
465
newtons first law of motion
This law states that an object remains at rest or moves in a straight line at constant speed unless it is acted on by an unbalanced force.
466
newtons second law of motion
This law states that the magnitude F of the unbalanced force on an object with a mass m is related to the magnitude a of the acceleration of the object by the equation F = ma, the acceleration being in the same direction as the unbalanced force.
467
orbital quantum number
The number l used to label the subshells within a given shell of electrons. When labelling quantum states it may take any value from 0 up to n–1, where n is the principal quantum number.
468
orbitals
The word orbital is used to describe the waveforms that electrons make in hydrogen and other atoms.
469
period
In physics, the interval of time it takes for a single complete cycle of a wave to pass a fixed point. Symbol: T. Equal to one over the frequency of a wave. T = 1/f
470
photon
A particle of light or other electromagnetic radiation. Photons of the same frequency have exactly the same amount of energy, called a quantum of energy. Photons have no mass or electric charge and do not experience the electromagnetic interaction.
471
planck constant
The fundamental constant relating to quantum mechanics. It has the value h = 6.63 × 10−34 J s, or 4.14 × 10−15 eV Hz−1. The Planck constant is defined by the equation Eph = hf linking energy of photons with frequency.
472
principal quantum number
The number n used to characterise the major electron shells of an atom
473
probability
The quantitative value for the chance or likelihood that a given outcome will occur. Probabilities have values between 0 and 1. A probability of 1 indicates a certainty; a probability of 0 indicates an event which will never occur.
474
quantum
(plural: quanta)
1. The amount of energy carried by a single photon of light or other electromagnetic radiation.
2. Used to refer to any system in which energy levels exist, and which therefore emit or absorb quanta of light, and/or in which the constituent particles have indeterminate positions and speeds.
475
quantum mechanics
A theory of the behaviour of small objects with three important ideas: objects have wave−particle duality, have fixed amounts of energy known as quanta, and are governed by the laws of chance.
476
quantum number
One of a set of (up to four) numbers used to describe the quantum state of an atom or other quantum system.
477
quantum state
A description of the properties of an atom or other quantum system. In general, each energy level of an atom will correspond to more than one quantum state.
478
quantum system
A system of particles which are bound together and so exhibit quantised energy levels. Nuclei, atoms and molecules are all examples of quantum systems.
479
schrodinger model of the atom
The fully quantum model of the atom, based on the equation developed by Erwin Schrödinger.
480
screening
Screening is the process by which electrons in orbitals close to the nucleus reduce or screen the positive charge associated with the nucleus. Screening modifies the energy of electrons in orbitals further from the nucleus.
481
spectrum
A display (such as a graph or a photograph) of the distribution of light or other types of radiation versus the wavelength (or frequency or energy) of the radiation. It indicates the intensity of light at each different wavelength. A spectrum may be a continuous spectrum or may show emission lines or absorption lines.
482
spin quantum number
A quantum number represented by the symbol ms used when labelling quantum states. It may take values of -1/2 or 1/2 only
483
standing waves
A wave that does not travel
484
wave
A periodic (regularly repeating) disturbance that transports energy from one place to another. Characterised by its wavelength, frequency (or period) and amplitude.
485
waveform
The shape of a wave
486
wavelength
The distance between one part of the wave profile, at a particular instant in time, and the next identical part of the wave profile at the same instant in time. Two adjacent crests of the wave are a convenient pair of locations to use for this definition, although any pair of similar points will do. Wavelength λ is related to frequency f and speed v of a wave by v = fλ
487
wave-particle duality
Used to describe the fact that light and other forms of electromagnetic radiation travel from place to place like a wave but interact with matter as if it is composed of a stream of particles called photons. Similarly, electrons and other subatomic particles also propagate like waves but interact like particles.
488
acid
A substance that donates protons.
489
avogadros constant
The number of units that are present in one mole of a substance. It has the value 6.02 × 1023 mol–1.
490
balanced chemical equation
A symbol chemical equation where the total number of each type of reactant atom is equal to the total number of each type of product atom.
491
chemical change
A change to a substance that leads to a modification of its chemical composition.
492
complex carbohydrate
Carbohydrates consisting of many sugar units (polysaccharides).
493
curly arrows
A representation used in reaction mechanisms to show the movement of electrons.
494
deposition
The direct conversion of a gas (vapour) into a solid without passage through a liquid phase.
495
disaccharide
A molecule formed by the combining of two monosaccharides. An example is sucrose.
496
dissociation
The process where a covalent bond is broken.
497
functional group
In many reactions of organic compounds, only certain groups of atoms are directly involved. It is the nature of these groups of atoms that primarily determines the type of reaction that takes place, and the particular chemical properties of an organic molecule. Such groups of atoms are called functional groups.
498
hydrated ions
Positive or negative ions that interact with several water molecules. They are formed when an ionic substance is dissolved in water.
499
molar mass
The mass of one mole of a substance.
500
mole
The amount of a species that contains Avogadro’s constant of that species. Its mass is obtained by adding up the relative atomic masses of the atoms in the formula unit.
501
monosaccharide
A sugar that cannot be broken down to anything simpler. Common monosaccharides are glucose, fructose and ribose.
502
organic chemistry
The branch of chemistry that deals with the properties and reactions of carbon-based compounds.
503
partial changes
Charges obtained by atoms due to the unequal sharing of a bonding electron density as a consequence of electronegativity differences between bonded atoms.
504
phospholipid
A major component of cell membranes, based on a glycerol unit that contains two water-immiscible hydrocarbon chains together with a third, charged, water-miscible group linked to the glycerol unit through a phosphate group. Phospholipids, together with proteins, are the key components of biological membranes.
505
pH scale
A scale that provides a convenient measure of the acidity of an aqueous solution. The lower the pH, the more acid the solution. A pH of 7 corresponds to a neutral solution.
506
physical change
A change which alters the physical nature of a substance without changing its chemical composition.
507
polar bond
A covalent bond in which the bonding electrons are not evenly distributed due to electronegativity differences between the bonded atoms.
508
reaction mechanism
A step-by-step series of events that explain how reactant molecules are converted into product molecules.
509
relative formula mass
The sum of the relative atomic masses of the atoms found in the chemical formula of a substance.
510
simple carbohydrate
Carbohydrates consisting of one sugar unit (monosaccharides) or two sugar units (disaccharides).
511
skeletal formula
A shorthand method of representing molecular structures that shows the basic framework of the structure, together with the important atom groupings, without showing all the atoms present.
512
state symbols
Symbols that represent and describe the physical state of a substance.
513
strong acid
An acid that, when dissolved in water, is completely dissociated into aqueous hydrogen ions, H+(aq), and the accompanying aqueous negative ions.
514
sublimination
The direct conversion of a solid into a gas (or vapour) without passage through a liquid phase.
515
weak acid
An acid that, when dissolved in water, is only partly dissociated into aqueous hydrogen ions, H+ (aq), and the accompanying aqueous negative ions
516
aqueous solubility
The ability of a substance to dissolve in water
517
bond enthalpy
The energy required to break a bond
518
compound
The name given to a substance made up from two or more different types of atom
519
dicoordinate
Bonded to two other atoms
520
dipole
The separation of a pair of positive and negative charges across a distance
521
electronegativity
A measure of the ability of an atom to attract electrons to itself when forming chemical bonds.
522
element
The name given to a substance made up from one type of atom
523
enthalpy of vaporisation
The energy change required to vaporise a substance from the liquid to the gaseous state
524
hydrophobic
Having poor solubility in water
525
isomers
Compounds that have the same molecular formula but different structural formula.
526
lewis structures
The dot-cross diagrams that represent the electron sharing involved in covalent bonding between atoms
527
london forces
The weak interaction between molecules that results from the temporary unequal sharing of electrons in a covalent bond.
528
lone pair electrons
Electrons that have paired up but are not used for bonding to another atom (also known as 'non-bonding electron pairs'). Lone pair electrons are present on atoms from groups 15, 16 and 17 of the Periodic Table.
529
molecule
A group of atoms covalently bonded together that is the smallest unit of a substance which gives rise to the chemical and physical properties of that substance.
530
non-bonding electron pairs
Electrons that have paired up but are not used for bonding to another atom (also known as 'lone pair electrons'). Non-bonding electron pairs are present on atoms from groups 5, 6 and 7 of the Periodic Table.
531
non-ionic surfactant
Uncharged compounds that contain both a water-soluble component and an oil-soluble component
532
relative atomic mass
The ratio of the mass of an atom of an element to 1/12th of the mass of the carbon-12 isotope
533
relative molecular mass
The sum of the relative atomic masses of all the constituent atoms in a molecule
534
surfactant
A compound that has both polar and non-polar regions in its molecular structure, such that it can interact with both polar and non-polar materials
535
tetracoordinate
Bonded to four other atoms
536
tricoordinate
Bonded to three other atoms
537
valency
The number of shared electron-pair bonds that an atom must form if it is to attain an electronic structure with a full outer shell of electrons.
538
3'
Describes one of two key carbon atoms in nucleotide ribose sugars that are involved in the polymerisation of nucleotides to form nucleic acids. Pronounced 'three prime'.
539
3' end
One of the two ends of a nucleic acid molecule, corresponding to the position of the 3’ carbon within the ribose sugars of that nucleic acid.
540
5'
Describes one of two key carbon atoms in nucleotide ribose sugars that are involved in the polymerisation of nucleotides to form nucleic acids. Pronounced 'five prime'.
541
5' end
One of the two ends of a nucleic acid molecule, corresponding to the position of the 5’ carbon within the ribose sugars of that nucleic acid. Considered the start of the molecule.
542
adenine
One of the four chemical bases used in DNA, and one of the four bases used in RNA.
543
amino acids
Chemical monomers that make proteins.
544
antiparallel
Adjective used to describe the strands in a double-stranded DNA molecule, which run in parallel to each other but in opposite directions.
545
antisense strand
(or noncoding strand or template strand) Terms used during gene transcription to describe the strand of chromosomal DNA that is used as the template and whose sequence is complementary to the mRNA molecule produced.
546
base
Chemical groups that are one of the component parts of a nucleotide, together with phosphate and a ribose sugar.
547
base pairing
Hydrogen bonding between complementary nucleotides that allows DNA to become double stranded.
