Chemistry Keywords Flashcards
1
Q
Cathode
A
The negative electrode in electrolysis.
2
Q
Neutral
A
A solution with a pH value of 7 which is neither acidic nor alkaline. Alternatively, something that carries no overall electrical charge
3
Q
Particulate
A
Small solid particle given off from motor vehicles as a result of incomplete combustion of its fuel.
4
Q
Reproducible
A
A measurement is reproducible if the investigation is repeated by another person, using different equipment and the same results are obtained.
5
Q
Anhydrous
A
Describes a substance that does not contain water.
6
Q
Formulation
A
A mixture that has been designed as a useful product.
7
Q
Fermentation
A
The reaction in which the enzymes in yeast turn glucose into ethanol and carbon dioxide.
8
Q
Endothermic
A
A reaction that takes in energy from the surroundings.
9
Q
Reaction profile
A
The relative difference in the energy of reactants and products.
10
Q
Double bond
A
A covalent bond made by the sharing of two pairs of electrons.
11
Q
Rusting
A
The corrosion of iron.
12
Q
Incomplete combustion
A
When a fuel burns in insufficient oxygen, producing carbon monoxide as a toxic product.
13
Q
Order of magnitude
A
A comparison of the size of values. Two values are the same order of magnitude if their difference in size is small in comparison to other values being compared.
14
Q
Thermosoftening polymer
A
Polymer that forms plastics which can be softened by heating, then remoulded into different shapes as they cool down and set.
15
Q
Mean
A
The arithmetical average of a series of numbers.
16
Q
Fullerene
A
Form of the element carbon that can exist as large cage-like structures, based on hexagonal rings of carbon atoms.
17
Q
Mass number
A
The number of protons plus neutrons in the nucleus of an atom.
18
Q
Delocalised electron
A
Bonding electron that is no longer associated with any one particular atom.
19
Q
Polymer
A
A substance made from very large molecules made up of many repeating units (monomers).
20
Q
Risk
A
The likelihood that a hazard will actually cause harm.
21
Q
Categoric variable
A
Categoric variables have values that are labels. For example types of material.
22
Q
Mixture
A
When some elements or compounds are mixed together and intermingle but do not react together (i.e. no new substance is made). A mixture is not a pure substance.
23
Q
Saturated hydrocarbon
A
Describes a hydrocarbon with only single bonds between its carbon atoms. This means that it contains as many hydrogen atoms as possible in each molecule.
24
Q
Alloy
A
A mixture of two or more elements, at least one of which is a metal.
25
Reactivity series
A list of elements in order of their reactivity.
26
Electronic structure
A set of numbers to show the arrangement of electrons in their shells (or energy levels).
27
Ore
Ore is rock which contains enough metal to make it economically worthwhile to extract the metal.
28
Strong acids
These acids completely ionise in aqueous solutions.
29
Viscosity
The resistance of a liquid to flowing or pouring; a liquid’s ‘thickness’
30
Fair test
A fair test is one in which only the independent variable has been allowed to affect the dependent variable.
31
Distillation
Separation of a liquid from a mixture by evaporation followed by condensation.
32
Unsaturated hydrocarbon
A hydrocarbon whose molecules contains at least one carbon–carbon double bond.
33
Reactant
A substance we start with before a chemical reaction takes place.
34
Independent variable
The variable for which values are changed or selected by the investigator.
35
Stainless steel
A chromium-nickel alloy of steel which does not rust.
36
Shell
An area in an atom, around its nucleus, where electrons are found.
37
Displacement reaction
A reaction in which a more reactive element takes the place of a less reactive element in one of its compounds or in solution.
38
Quantitative data
Data that is numerical or a measurement.
39
Ratio
A way of comparing two or more quantities, showing how many times one quantity is contained within the other.
40
Bond energy
The energy required to break a specific chemical bond.
41
Fraction
Hydrocarbons with similar boiling points separated from crude oil.
42
Alkali metal
Elements in Group 1 of the periodic table which have 1 electron in their outer shell.
43
Hydrocarbon
A compound containing ONLY hydrogen and carbon.
44
Retention factor
A measurement from chromatography: it is the distance a spot of substance has been carried above the baseline divided.
45
Nanoscience
The study of very tiny particles or structures between 1 and 100 nanometres in size – where 1 nanometre = 0.000000001 metres.
46
Covalent bond
The bond between two atoms that share one or more pairs of electrons.
47
Collision theory
An explanation of chemical reactions in terms of reacting particles colliding with sufficient energy for a reaction to take place.
48
Carbon steel
Alloy of iron containing controlled, small amounts of carbon.
49
Inert
Unreactive.
50
Fractional distillation
A way to separate liquids from a mixture of liquids by boiling off the substances at different temperatures, then condensing and collecting the liquids.
51
Mole
The amount of substance in the relative atomic or formula mass of a substance in grams.
52
Neutron
A dense particle found in the nucleus of an atom. It is electrically neutral, carrying no charge.
53
Atom economy
A measure of the amount of starting materials that end up as useful products.
54
Continuous variable
Can have values (called a quantity) that can be given by measurement (for example, mass, volume, temperature, etc.).
55
Significant figures (s.f.)
The important digits within a number. All non-zero digits are significant. Zeros may be significant if followed by another nonzero digit.
56
Le Châtelier’s Principle
When a change in conditions is introduced to a system at equilibrium, the position of equilibrium shifts so as to cancel out the change.
57
Relative atomic mass
The average mass of the atoms of an element compared with carbon-12 (which is given a mass of exactly 12). The average mass must take into account the proportions of the naturally occurring isotopes of the element.
58
Qualitative data
Data that is descriptive or categorical.
59
Galvanised
Iron or steel objects that have been protected from rusting by a thin layer of zinc metal at their surface.
60
Isotope
Atoms that have the same number of protons but different number of neutrons, i.e., they have the same atomic number but different mass numbers.
61
Homologous series
A group of related organic compounds that have the same functional group.
62
Base
The oxide, hydroxide, or carbonate of a metal that will react with an acid, forming a salt as one of the products. (If a base dissolves in water it is called an alkali). Bases are proton (H+ ion) acceptors.
63
Recycle
The process in which waste materials are processed to be used again.
64
Balanced symbol equation
A symbol equation in which there are equal numbers of each type of atom on either side of the equation.
65
Control group
If an experiment is to determine the effect of changing a single variable, a control is often set up in which the independent variable is not changed, thus enabling a comparison to be made. If the investigation is of the survey type a control group is usually established to serve the same purpose.
66
Respiration
The process by which food molecules are broken down to release energy for the cells.
67
Precipitate
An insoluble solid formed by a reaction taking place in solution.
68
Hypothesis
A proposal intended to explain certain facts or observations.
69
Relative formula mass Mr
The total of the relative atomic masses, added up in the ratio shown in the chemical formula, of a substance.
70
Filtration
The technique used to separate substances that are insoluble in a particular solvent from those that are soluble
71
Climate change
The change in global weather patterns that could be caused by excess levels of greenhouse gases in the atmosphere.
72
Directly proportional
A relationship that, when drawn on a line graph, shows a positive linear relationship that crosses through the origin.
73
Atomic number
The number of protons (which equals the number of electrons) in an atom. It is sometimes called the proton number.
74
Equilibrium
The point in a reversible reaction at which the forward and backward rates of reaction are the same. Therefore, the amounts of substances present in the reacting mixture remain constant.
75
Intermolecular forces
The attraction between the individual molecules in a covalently bonded substance.
76
Line of best fit
A line that represents the general trend of data.
77
pH
A number which shows how strongly acidic or alkaline a solution is
78
Transition element
Element from the central block of the periodic table
79
Halogens
The elements found in Group 7 of the periodic table. They have 7 electrons in their outer shell.
80
Gradient
All the elements in the columns (labelled 1 to 7 and 0) in the periodic table.
81
Word equations
A way of describing what happens in a chemical reaction by showing the names of all reactants and the products they form.
82
Nucleus (of an atom)
The very small and dense central part of an atom that contains protons and neutrons.
83
Range
The maximum and minimum values of the independent or dependent variables.
84
Oxidised
Describes a substance that has had oxygen added to it / or has lost electrons.
85
Electrical (chemical) cells
Contain chemicals that react to produce electricity.
86
Dependent variable
The variable for which the value is measured for each and every change in the independent variable.
87
Sacrificial protection
An effective way to prevent rusting whereby a metal more reactive than iron (such as zinc or magnesium) is attached to or coated on an object.
88
Percentage yield
The actual mass of product collected in a reaction divided by the maximum mass that could have been formed in theory, multiplied by 100.
89
Prediction
A forecast or statement about the way something will happen in the future.
90
Ionic equation
An equation that shows only those ions or atoms that change in a chemical reaction.
91
Exothermic
A reaction that transfers energy to the surroundings.
92
Ceramics
Materials made by heating clay, or other compounds, to high temperatures (called firing) to make hard, but often brittle, materials, which make excellent electrical insulators.
93
Accurate
A measurement is considered accurate if it is judged to be close to the true value.
94
Diffusion
The automatic mixing of liquids and gases as a result of the random motion of their particles.
95
Hydrated
Describes a substance that contains water in its crystals.
96
Electron
A tiny particle with a negative charge. Electrons orbit the nucleus of atoms or ions in shells.
97
Compound
A substance made when two or more elements are chemically bonded together.
98
Product
A substance made as a result of a chemical reaction.
99
Chromatography
The process whereby small amounts of dissolved substances are separated by running a solvent along a material such as absorbent paper.
100
Alkane
Saturated hydrocarbon with the general formula CnH2n+2.
101
Variable
Physical, chemical or biological quantity or characteristic.
102
Titration
A method for measuring the volumes of two solutions that react together.
103
Alkene
Unsaturated hydrocarbon which contains a carbon–carbon double bond. Its general formula is CnH2n.
104
Covalent bonding
The attraction between two atoms that share one or more pairs of electrons.
105
Valid
Suitability of the investigative procedure to answer the question being asked.
106
Half equation
An equation that describes reduction (gain of electrons) or oxidation (loss of electrons).
107
Reversible reaction
A reaction in which the products can re-form the reactants.
108
Biodegradable
Materials that can be broken down by microorganisms.
109
Burette
A long glass tube with a tap at one end and markings to show volumes of liquid; used to add precisely known volumes of liquids to a solution in a conical flask below it.
110
Life cycle assessment
Carried out to assess the environmental impact of products, processes or services at different stages in their life cycle.
111
Standard form
A way of displaying large and small numbers.
112
Closed system
A system in which no matter enters or leaves.
113
Data
Information, either qualitative or quantitative, that has been collected.
114
Blast furnace
The huge reaction vessels used in industry to extract iron from its ore.
115
Continuous data
Continuous data Data that can take any value.
116
Avagadro constant
The number of atoms, molecules, or ions in a mole of any substance.
117
Ion
A charged particle produced by the loss or gain of electrons
118
State symbol
The abbreviations used in balanced symbol equations to show if reactants and products are solid (s), liquid (l), gas (g) or dissolved in water (aq).
119
End point
The point in a titration where the reaction is complete and titration should stop.
120
Oxidation
The reaction when oxygen is added to a substance / or when electrons are lost.
121
Flammable
Easily ignited and capable of burning rapidly.
122
Thermosetting polymer
Polymer that can form extensive cross-linking between chains, resulting in rigid materials which are heat-resistant.
123
Giant lattice
A huge 3D network of atoms or ions.
124
Relationship
The link between the variables that were investigated.
125
Proton
A tiny positive particle found inside the nucleus of an atom.
126
Fuel cells
Sources of electricity that are supplied by an external source of fuel.
127
Non-renewable
Something which cannot be replaced once it is used up.
128
Repeatable
A measurement is repeatable if the original experimenter repeats the investigation using the same method and equipment and obtains the same or precise results.
129
Control variable
A variable which may, in addition to the independent variable, affect the outcome of the investigation and therefore has to be kept constant or at least monitored.
130
Giant covalent structure
A huge 3D network of covalently bonded atoms.
131
Atmosphere
The relatively thin layer of gases that surround planet Earth.
132
Precise
A precise measurement is one in which there is very little spread about the mean value. Precision depends only on the extent of random errors – it gives no indication of how close results are to the true (accurate) value.
133
Cracking
The reaction used in the oil industry to break down large hydrocarbons into smaller, more useful ones.
134
Electrolysis
The breakdown of a substance containing ions by electricity.
135
Periodic table
An arrangement of elements in the order of their atomic numbers, forming groups and periods.
136
Alkali
Its solution has a pH value more than 7.
137
Anode
The positive electrode in electrolysis.
138
Functional group
An atom or group of atoms that give organic compounds their characteristic reactions
139
Composites
Materials made of two or more different materials, containing a matrix or binder surrounding and binding together fibres or fragments of another material which acts as the reinforcement.
140
Dot and cross diagram
A drawing to show only the arrangement of the outer shell electrons of the atoms or ions in a substance.
141
Monomers
Small reactive molecules that react together in repeating sequences to form a very large molecule (a polymer).
142
Carbon footprint
The total amount of carbon dioxide and other greenhouse gases emitted over the full life cycle of a product, service or event.
143
Atom
The smallest part of an element that can still be recognised as that element.
144
Flame emission spectroscopy
A method of instrumental analysis in which the light given off when a sample is placed in a flame produces characteristic line spectra to identify and measure the concentration of metal ions in the sample.
145
Molecular formula
The chemical formula that shows the actual numbers of atoms in a particular molecule.
146
Catalyst
A substance that speeds up a chemical reaction by providing a different pathway for the reaction that has a lower activation energy. The catalyst is chemically unchanged at the end of the reaction.
147
Discrete data
Data that can only take certain values.
148
Universal indicator
A mixture of indicators that can change through a range of colours to show how strongly acidic or alkaline liquids and solutions are.
149
DNA (deoxyribonucleic acid)
A large organic molecule that encodes genetic instructions for the development and functioning of living organisms and viruses.
150
Aqueous solutions
The mixture made by adding a soluble substance to water.
151
Activation energy
The minimum energy needed for a reaction to take place.
152
Neutralisation
The chemical reaction of an acid with a base in which a salt and water are formed. If the base is a carbonate or hydrogen carbonate, carbon dioxide is also produced in the reaction.
153
SI system of units
A system of units for physical quantities that are considered the standard units.
154
Noble gases
The very unreactive gases found in Group 0 of the periodic table. Their atoms have very stable electronic structures.
155
Reduction
A reaction in which oxygen is removed or electrons are gained.
156
Element
A substance made up of only one type of atom. An element cannot be broken down chemically into any simpler substance.
157
Weak acids
Acids that do not ionise completely in aqueous solutions
158
Electrolyte
A liquid, containing free-moving ions, which is broken down by electricity in the process of electrolysis.
159
Catalytic converter
Fitted to exhausts of vehicles to reduce pollutants released.
160
Pipette
A glass tube used to measure accurate volumes of liquids.
161
Salt
A salt is a compound formed when some or all of the hydrogen in an acid is replaced by a metal.
162
Biofuel
Fuel made from animal or plant products.
163
Line graph
Used when both variables are continuous. The line should normally be a line of best fit, and may be straight or a smooth curve.
164
Hazard
A hazard is something (e.g., an object, a property of a substance or an activity) that can cause harm.
165
Anomalies
Results that do not match the pattern seen in the other data collected or are well outside the range of other repeat readings (outliers).
166
Ionic bond
The electrostatic force of attraction between positively and negatively charged ions.
167
Law of the conservation of energy
The total mass of the products formed in a reaction is equal to the total mass of the reactants.
168
Acid
When dissolved in water, its solution has a pH value less than 7. Acids are proton (H+ ion) donors.
169
Thermal decomposition
The breakdown of a compound by heating it.
