Glossary Flashcards
1
Q
absolute zero
A
273C or 0 K. Molecules and atoms have minimum kinetic energy at this temperature.
2
Q
acid
A
Substance capable of donating a hydrogen ion (proton).
3
Q
acid rain
A
Rainwater that has reacted with acidic emissions from industry and has a pH less than 5.5.
4
Q
acidic oxide
A
an oxide generally of a nonmetal that either reacts with water to form an acid or reacts with a base. acidic solution An aqueous solution in which [H+] > [OH]. At 25C the pH
5
Q
actinides
A
The set of elements with atomic number between 90 and 103 in which the 5fsubshell is progressively filled.
6
Q
addition reaction
A
A reaction in which a molecule binds to an unsaturated hydrocarbon forming a single carbontocarbon bond. In this process two reactant molecules become one.
7
Q
aliquot
A
A volume of liquid measured by a pipette. alkali A soluble base.
8
Q
alkali metals
A
Group 1 metals.
9
Q
alkanes
A
Hydrocarbons with only single bonds between carbon atoms; general formula CnH2n+2.
10
Q
alkenes
A
Hydrocarbons with one double bond between two carbon atoms; general formula CnH2n.
11
Q
alkyl group
A
A group obtained by removing a hydrogen atom from an alkane with general formula CnH2n+1 e.g. methyl (CH3).
12
Q
allotropes
A
Different physical forms of the same element.
13
Q
alloy
A
A substance formed when other materials (e.g. carbon other metals) are mixed with a metal.
14
Q
alpha particle
A
A 42He nucleus emitted from the nucleus of an atom during radioactive decay.
15
Q
amorphous
A
Without structure.
16
Q
amount of substance
A
A measure used by chemists for counting particles; the unit is the mole.
17
Q
amphiprotic
A
The ability to act as an acid or a base.
18
Q
anion
A
A negatively charged ion.
19
Q
annealing
A
Heating a metal to a moderate temperature and then allowing it to cool slowly to make it softer and more ductile.
20
Q
anode
A
An electrode at which an oxidation reaction occurs.
21
Q
atom
A
The smallest part of an element that can take part in a chemical reaction.
22
Q
atom economy
A
A method of tracking the atoms in a reaction equation to calculate the mass of the atoms of reactants actually used to form product as a percentage of the total mass of reactants.
23
Q
atomic number
A
The number of protons in the nucleus of an atom.
24
Q
atomic radius
A
Half the distance between the nuclei in a molecule consisting of identical atoms.
25
Avogadros number (*N*A)
* *N*A the number of particles in a mole;
* *N*A = 6.023 1023 mol1.
* *N*A is the number of elementary particles (atoms) in exactly 12 g of carbon-12. is number is equal to 6.02 × 1023.
26
Avogadros law
At the same temperature and pressure equal volumes of all gases contain the same number of molecules.
27
base
A substance capable of accepting a hydrogen ion (proton).
28
basic oxide
An oxide of a metal which either reacts with water to form hydroxide ions or reacts with H3O+ ions.
29
basic solution
A solution where [H3O+] 7.
30
biosphere
That part of the Earths environment that supports life.
31
bonding electrons
Outershell electrons involved in covalent bonding.
32
Boyles law
P V1 at constant temperature.
33
brittle
Shatters when given a sharp tap.
34
BrnstedLowry theory
A theory that defines an acid as a proton (hydrogen ion) donor and a base as a proton acceptor.
35
carbonoxygen cycle
The path taken by carbon and oxygen atoms as they react to form new compounds and move around the biosphere.
36
catalyst
A substance that increases the rate of a reaction but are not consumed in the reaction. cathode An electrode at which a reduction reaction occurs.
37
cation
A positively charged ion.
38
Charles law
V T at constant pressure.
39
chlorination
Reaction with chlorine.
40
chlorofluorocarbons
Synthetic compounds containing chlorine fluorine and carbon atoms e.g. CF2Cl2.
41
colloids
Very small particles spread throughout a liquid solid or gas. These particles are bigger than single molecules but so small that they do not settle on standing.
42
combined gas equation
P1V1 = P2V2 n1T1 n2T2
43
combustion
Reaction with oxygen.
44
compound
A pure substance composed of atoms of two or more elements which have chemically combined in fixed proportions.
45
concentration
A measure of the amount of solute dissolved in a given quantity of solvent or solution.
46
conductivity of electricity
Allows an electric current to pass through.
47
conjugate acid
The conjugate acid of a base contains one more hydrogen ion (proton) than the base.
48
conjugate base
The conjugate base of an acid contains one less hydrogen ion (proton) than the acid.
49
conservation of mass
see law of conservation of mass.
50
core charge
the attraction felt by the outershell electrons to the nuclear charge. Core charge can be calculated as atomic number all electrons except those in the outer shell.
51
corrosion
The reaction of a metal with oxygen and other substances in its environment.
52
covalency
The number of electrons an element shares in a covalent molecular compound.
53
covalent bond
The force of attraction formed when one or more pairs of electrons are shared between two nuclei.
54
covalent layer lattice
A twodimensional array of atoms held together by covalent bonds. Weak forces operate between the layers.
55
covalent molecular lattice
An arrangement of molecules into a lattice; the attractive forces between the molecules are weak. covalent network lattice An arrangement of atoms into a lattice in which there are strong covalent bonds between the atoms in all three dimensions.
56
crosslinks
Covalent links between polymer chains. The extent of crosslinking varies depending on use.
57
crystalline solid
A solid with a regular arrangement of particles.
58
crystallisation
Some solute comes out of solution to form crystals.
59
customised
Manufactured with specific properties to meet a need.
60
dblock
A block of elements in the periodic table known as the transition metals; the atoms of these metals have outershell electron configurations of d1s2 to d10s2.
61
decomposition
The breaking down of a compound to form two or more other compounds or elements.
62
delocalised electrons
Electrons that are not restricted to a region between two atoms.
63
desalination
The removal of salts from seawater to obtain fresh water.
64
dilute
A dilute solution is one in which the ratio of amount of solute to solvent or solution is low. dilution The addition of solvent to a solution to reduce its concentration.
65
dipole
A molecule that has two oppositely charged poles or ends.
66
dipoledipole interaction
Attractions between dipoles.
67
diprotic
A diprotic acid is capable of donating two hydrogen ions (protons); e.g. H2SO4.
68
dispersion force
The attraction that exists between molecules because of the instantaneous dipoles that form as electrons move randomly.
69
displacement
A process in which one substance replaces another.
70
dissociation
The separation of positive and negative ions as an ionic lattice melts or dissolves.
71
distillation
The separation of a liquid from a solid or other liquid by heating to cause evaporation followed by cooling to cause condensation.
72
dry ice
Solid carbon dioxide.
73
ductile
Able to be drawn into a thread.
74
elastic
Able to be stretched and then return to original shape when stretching force is removed.
75
elastomer
A material that returns to its original position after contraction or expansion.
76
electrochemical cell
A device that converts chemical energy into electrical energy.
77
electrochemical series
A list of chemical species arranged in order of their strength as oxidants.
78
electrolytic conductor or electrolyte
A solution or molten substance that conducts electricity by means of the movement of
79
electronegativity
The ability of an atom that is bonded to another atom to attract the bonding electrons towards itself.
80
electrovalency
The charge on an ion.
81
element
A substance composed of atoms with the same atomic number.
82
emission spectrum
A set of coloured lines on a black background obtained when light emitted by excited electrons as they move to a lower energy state is passed through a prism in a spectroscope.
83
empirical formula
A formula of a compound that shows the elements present and their ratio.
84
enhanced greenhouse effect
An increase in the temperature of the atmosphere due to an increased concentration of greenhouse gases such as carbon dioxide and water vapour.
85
equivalence point
The point in a titration when the reactants have reacted in their correct mole ratios.
86
excess reagent
Reagent that is present in an amount greater than that required in a reaction.
87
excited state
The state of an atom ion; etc. in which one or more electrons have absorbed energy and are not in their lowest energy levels.
88
fblock
A block of metallic elements in the periodic table; known as the lanthanides and actinides; in which the 4f and 5fsubshells are progressively being filled.
89
fermentation
The conversion of sugar solutions; in the presence of yeast to form ethanol and carbon dioxide.
90
filtrate
The liquid that passes through a filter.
91
first ionisation energy
The minimum amount of energy that is required to remove the highest energy electron from an atom; in the gaseous state.
92
flocculation
Small suspended particles come together to form larger heavier particles which are usually insoluble.
93
fossil fuels
Coal oil and natural gas; fuels derived from the remains of animal and plant matter.
94
fractional distillation
The separation of a mixture into different fractions; each containing a number of gases with similar boiling temperatures.
95
galvanic cell
A device that converts chemical energy into electrical energy.
96
galvanometer
A device used to detect the movement of charge.
97
general gas equation
The equation that describes the behaviour of a gas: pV = nRT.
98
global warming
The gradual increase of Earths temperature.
99
green chemistry
A set of principles and practices that aim to reduce generation and use of hazardous materials in chemical products.
100
greenhouse effect
A warming of the Earths atmosphere due to the absorption of infrared radiation by gases such as carbon dioxide and water vapour.
101
greenhouse gases
Gases which are able to absorb infrared radiation coming from the Earths surface; e.g. carbon dioxide and methane.
102
ground state
A term used to describe atoms in which the electrons are in their lowest possible energy levels. group A vertical column of elements in the periodic table.
103
haemoglobin
A protein in blood that transports oxygen around the body to the cells.
104
half equation
An equation involving either an oxidation or a reduction process. The electrons lost or gained in this process are shown in the equation.
105
halogens
Elements of group 17 of the periodic table.
106
halons
Synthetic compounds containing chlorine bromine and carbon atoms.
107
homologous series
A series of organic compounds with similar chemical properties (same functional group) and in which each member differs by a CH2 group from the previous member.
108
hydrated ions
Ions surrounded by water molecules in aqueous solution or crystalline solids.
109
hydrocarbon
A compound of carbon and hydrogen.
110
hydrogen bond
A strong dipoledipole attraction that forms between molecules in which hydrogen is bonded to one of the electronegative elements nitrogen oxygen and fluorine.
111
hydronium ion
The H3O+ ion.
112
hydrophilic
Waterloving substances; i.e. they are attracted to water.
113
hydrophobic
Waterfearing substances; their attraction to water molecules is too weak for them to dissolve.
114
ideal gas
A gas that obeys the general gas equation at all temperatures and pressures.
115
impressed current
A lowvoltage power supply that is used to force electrons on to an electrode to ensure that a reduction reaction occurs at its surface.
116
indicator
A substance that has different colours in its acid and base forms.
117
interstitial alloy
Alloy made by adding smaller atoms to a metal.
118
ion
A positively or negatively charged atom or group of atoms.
119
iondipole attraction
The force of attraction between an ion and a polar molecule.
120
ion exchange
A process in which ions are removed from a solution by adsorption onto the surface of a resin. The resin releases other ions (usually H+ or OH) into the solution in exchange.
121
ionic bond
The electrostatic attraction between oppositely charged ions.
122
ionic equation
An equation that includes only the ions involved in the reaction.
123
ionic product of water
The product of the hydrogen ion concentration and hydroxide ion concentration.
124
ionisation
(i) The reaction of a molecular substance with a solvent to form ions in solution; (ii) the removal of one or more electrons from an atom or ion.
125
ionisation energy
The minimum amount of energy that is required to remove an electron from an atom or ion, in the gaseous state.
126
isomers (structural isomers)
Molecules with the same molecular formula but different structures. isotope An atom with a specific atomic and mass number.
127
isotopes
Atoms with the same atomic number but different mass numbers.
128
kelvin scale
The absolute temperature scale (K = oC + 273).
129
kinetic energy
The energy that a particle or body has because of its motion.
130
lanthanides
The set of elements with atomic numbers between 58 and 71, in which the 4fsubshells are progressively being filled.
131
latent heat
The energy needed to change the state of a substance at its melting or boiling temperature.
132
latent heat of fusion
The energy required to change a fixed amount of solid to liquid at its melting temperature.
133
latent heat of vaporisation
The energy required to change a fixed amount of liquid to a gas at its boiling temperature.
134
lattice
A regular arrangement of large numbers of atoms, ions or molecules.
135
law of conservation of mass
During a chemical reaction the total mass of the reactants is equal to the total mass of the products.
136
limiting reagent
The reagent in a chemical reaction that determines the amounts of products formed. lone pair A pair of outershell or valence electrons that is not involved in bonding.
137
main group elements
Elements in groups 1, 2 and 1318.
138
malleable
Able to be bent or beaten into sheets.
139
mass number
The number of protons and neutrons in the nucleus of an atom.
140
mass spectrometer
An instrument designed to measure the masstocharge ratio of particles.
141
mass spectrum
A plot of the isotopic mass, relative to 12C, against the relative abundance of each isotope present in a sample.
142
metalloids
Elements, such as germanium, silicon, arsenic and tellurium, that display both metallic and nonmetallic properties.
143
molar mass
The mass of a mole of a substance, measured in g mol1.
144
molar volume
The volume occupied by 1 mole of gas at a specified set of conditions. At SLC, the molar volume of gases is 24.5 L mol1.
145
molarity
The amount of solute (mole) dissolved in 1 litre of solution.
146
mole
The amount of substance that contains the same number of fundamental particles as there are atoms in 12 g of 126C; symbol n.
147
mole ratio
The ratio of moles of one substance to moles of another substance in a chemical equation.
148
molecular formula
Indicates the actual number of atoms of each element in a molecule.
149
molecule
Two or more atoms held together by covalent bonds.
150
monomer
A compound made up of small molecules that are able to bond to form longchain molecules.
151
monoprotic
An acid capable of donating only one hydrogen ion (proton).nanoparticle Extremely small particles that have a diameter ranging typically from 1 nm (109 m) to about 100 nm.
152
nano science
The study of nanoparticles and their properties
153
nanotechnology
The application of nanoscience to make useful devices.
154
neutral solution
A solution in which the concentration of H3O+(aq) ions equals the concentration of OH(aq) ions. neutralise To react an acid with a base to form a solution of a salt and water.
155
neutron
A neutral particle found in the nucleus of an atom.
156
nitrogenfixing bacteria
Bacteria that are able to convert atmospheric nitrogen into nitrate and ammonium ions. They are usually found in the nodules that are present in the roots of legumes, such as peas, beans, clover and lucerne.
157
nitrogenoxygen cycle
The path taken by nitrogen and oxygen atoms as they react to form new compounds and move around the biosphere.
158
noble gas
The unreactive gaseous elements of group 18 of the periodic table.
159
nonbonding electrons
Outer shell or valence electrons which are not involved in bonding; also called lone pairs. nucleus The small, very dense centre of an atom, composed of protons and neutrons.
160
octet
Group of eight.
161
orbit
The path that an electron was thought to take as it moved around the nucleus.
162
orbital
Regions of space in which electrons move. carbonates.
163
oxidant
A substance that causes another substance to undergo an oxidation reaction; an oxidant accepts one or more electrons from the substance it oxidises.
164
oxidation
A reaction in which a substance loses one or more electrons or undergoes an increase in oxidation number.
165
oxidation number
Numbers that are assigned to elements to determine if a reaction can be classified as a redox reaction. Although they have no physical meaning, the numbers are assigned on the basis of a set of rules that assumes that all covalent bonds, except those between like atoms, are polar.
166
oxidised
When a substance has lost one or more electrons.
167
ozone layer
A region in the stratosphere, 1030 km above the Earths surface, with a higher concentration of ozone than other regions of the atmosphere.
168
partial pressure
The pressure exerted by one component of a mixture of gases.
169
Pauli exclusion principle
The principle that states that an atomic orbital can hold 0, 1 or 2 electrons.
170
pblock
The block containing the groups 1318 elements in the periodic table, which has atoms with outershell electron configurations of s2p1 to s2p6.
171
percentage by mass of an element
The mass of individual elements in a compound expressed as a percentage of the mass of the compound.
172
period
A horizontal row of elements in the periodic table.
173
periodic law
The properties of elements vary periodically with their atomic number.
174
periodic table
An arrangement of elements in order of increasing atomic number; the start of a new period corresponds to the outer electron of that element beginning a new shell.
175
pH
A measure of acidity; pH = log10[H3O+(aq)].
176
photochemical smog
Air pollution produced through the action of sunlight on oxides of nitrogen and unburnt hydrocarbons to form ozone and other pollutants.
177
photon
A small packet of energy that has a particular wavelength. A light beam is made up of photons.
178
photosynthesis
The reaction that occurs in the leaves of plants between carbon dioxide and water, in the presence of sunlight and chlorophyll, to form glucose and oxygen.
179
polarised bond
A covalent bond in which the electrons are not shared equally between the two atoms.
180
polar molecule
A molecule that acts as a dipole; it has one or more polar covalent bonds, with the charge being distributed asymmetrically.
181
polymer
Very large covalent molecules which are composed of repeating units, usually longchain molecules. polymerisation Reaction in which many small molecules join to form a large molecule.
182
polyprotic
An acid capable of donating more than one hydrogen ion (proton) to a base.
183
precipitate
A solid formed during a reaction in which two or more solutions are mixed.
184
precipitation reaction
Reaction between substances in solution in which one of the products are insoluble. pressure The force exerted per unit area of a surface.
185
propellant
An unreactive gas that is compressed and used to disperse liquids.
186
proton
A positively charged particle found in the nucleus of an atom.
187
quanta
Photons.
188
quenching
Heating a metal to a moderate temperature and then cooling it rapidly to make it harder and more brittle.
189
organic
Relating to organisms, living things
190
organic chemistry
Chemistry of carboncontaining compounds with the exception of compounds such as oxides of carbon and carbonates
191
redox reaction
A reaction that involves both oxidation and reduction.
192
reductant
A substance that causes another substance to undergo a reduction reaction; a reductant donates one or more electrons to the substance it reduces.
193
reduction
A reaction in which a substance gains one or more electrons or undergoes a decrease in oxidation number.
194
relative atomic mass
The weighted mean of the relative isotopic masses of an element on the scale where 12C is 12 exactly; symbol Ar.
195
relative formula mass
The mass of a formula unit relative to the mass of an atom of 12C taken as 12 units exactly. It is numerically equal to the sum of the relative atomic masses of the atoms making up the formula.
196
relative isotopic mass
The mass of an atom of the isotope relative to the mass of an atom of 12C taken as 12 units exactly. relative molecular mass The mass of a molecule relative to the mass of an atom of 12C taken as 12 units exactly. It is numerically equal to the sum of the relative atomic masses of the atoms making up the molecule.
197
renewable energy sources
Sources of energy that do not use finite resources, e.g. wind power.
198
respiration
A biological process in which nutrients are broken down to simpler molecules with the release of energy.
199
reverse osmosis
A process by which pure water can be obtained from salt water. Pressure is applied to the salt water, causing a net flow of water molecules away from the solution through a semipermeable membrane.
200
sacrificial protection
Protecting a metal from corrosion by coating it with a more reactive metal that will be preferentially oxidised.
201
salinity
The presence of levels of salt in water and soil that can damage plants or inhibit their growth.
202
salt
A substance formed from a metal (or ammonium) cation and an anion.
203
salt bridge
Part of the internal circuit of an electrochemical cell; it allows anions to migrate to the half cell that contains the anode, and cations to migrate to the half cell that contains the cathode.
204
saturated
Carbonbased compounds containing only single bonds between carbon atoms.
205
saturated solution
A solution that cannot dissolve any more solute at the given temperature.
206
sblock
The block of groups 1 and 2 elements in the periodic table, which has atoms with outershell electron configurations of s1 or s2.
207
semistructural formula
A formula that summarises the structural formula without giving the arrangement of atoms in space. shell A region in which a group of electrons of similar energies moves around the nucleus.
208
solubility
A measure of the amount of solute dissolved in a given amount of solvent or solution, at a given temperature. solubility curve A plot of solubility versus temperature for a particular solute dissolved in a particular solvent.
209
solute
A substance that dissolves in a solvent, e.g. sugar.
210
solution
A homogeneous mixture of a solute dissolved in a solvent.
211
solvent
A substance, usually a liquid, which is able to dissolve a solute, e.g. water.
212
specific heat capacity
The amount of energy required to raise the temperature of an amount of substance, usually 1 gram, by 1C.
213
spectator ions
Ions that remain in a solution and are unchanged in the course of a reaction. Spectator ions are not included in ionic equations.
214
standard laboratory conditions (SLC)
Defined as 25oC (or 298 K) and 101.3 kPa pressure.
215
standard temperature and pressure (STP)
Defined as 0oC (or 273 K) and 101.3 kPa pressure. standard solution A solution of known concentration.
216
stratosphere
A region in the atmosphere beyond the troposphere where the temperature ranges from 25C to 25C.
217
strong acid
An acid that readily donates a hydrogen ion (proton) to water acting as a base.
218
strong base
A base that readily accepts a hydrogen ion (proton) from water acting as an acid.
219
structural formula
A formula that represents the threedimensional arrangement of atoms in a molecule.
220
sublimation
A process by which a substance goes directly from the solid phase to the gaseous phase without passing through a liquid phase.
221
substitutional alloy
Alloy made from elements of similar chemical properties and size.
222
supercritical fluid
A vapour which is heated above a certain critical temperature so that it cannot be liquefied no matter what pressure is applied. It has properties similar to those of gases in that it expands to fill any available space but it also has properties similar to those of liquids and can be used as a solvent.
223
supersaturated solution
An unstable solution that has more solute dissolved at that temperature than a saturated solution. surface energy The energy required to increase the surface area by a unit amount.
224
surface/interface
The boundary between two substances.
225
surface tension
The resistance of a liquid to increase its surface area.
226
tempering
After a metal has been quenched it is warmed again to a lower temperature to reduce its brittleness but to retain its hardness.
227
thermoplastic polymer
A polymer that will soften and can be moulded when heated but will become harder again when cooled.
228
titre
The volume of liquid, measured by a burette, used in a titration.
229
transition metals
The dblock of elements in the periodic table, which has atoms with outershell electron configurations of d1s2 to d10s2.
230
triprotic
An acid capable of donating three hydrogen ions (protons) to a base.
231
troposphere
A region in the inner atmosphere where the temperature ranges from 25C to 25C.
232
ultraviolet radiation
A form of highenergy radiation coming from the sun.
233
unsaturated
Carbonbased compounds containing double or triple bonds between carbon atoms.
234
unsaturated solution
A solution that contains less solute dissolved at that temperature than a saturated solution.
235
valence structure
A formula that depicts the shape of a molecule and in which lines are used to represent pairs of electrons. volume The amount of space that a substance occupies.
236
volumetric analysis
Analysis using measurement of volumes, e.g. titration.
237
water cycle
Continual cycling of solid, liquid and gaseous water in the biosphere.
238
weak acid
An acid that donates protons to a limited extent when water is the base.
239
weak base
A base that accepts hydrogen ions to a limited extent when water is the acid.
