A-level Chemistry key terms

A proton donor (Bronsted-Lowry) or an electron pair acceptor (Lewis).
1 of 123
Acid derivative
An organic compound related to a carboxylic acid of formula RCOZ, where Z=-Cl,-NHR,-OR or -OCOR
2 of 123
Activation energy
The minimum energy required by a particle to react. This is also the enthalpy change between the reactants and the transition state.
3 of 123
An organic compound with the general formula RCHO.
4 of 123
Alkaline earth metals
Metals in group 2 of the periodic table.
5 of 123
A hydrocarbon containing only C-C and C-H single bonds.
6 of 123
Pure elements which can exist in different physical forms (i.e. the atoms are arranged differently).
7 of 123
Anaerobic respiration
The process that releases energy and forms new compounds in the absence of oxygen.
8 of 123
Atom economy
This describes the efficiency of a chemical reaction. You divide the mass of desired product by the total mass of reactants, then multiply that by 100.
9 of 123
Atomic orbital
A region of space around an atomic nucleus where there's a high probability of finding an electron.
10 of 123
Avogadro constant
The total number of particles in one mole of a substance. = 6.022x(10^23).
11 of 123
A proton acceptor (Bronsted-Lowry) or an electron pair donor (Lewis).
12 of 123
Base peak
The peak representing the ion of greatest abundance (i.e. the tallest peak) in a mass spectrum.
13 of 123
Bond dissociation enthalpy
The enthalpy change required to break a covalent bond with all species in the gaseous state.
14 of 123
Asolution that resists change of pH when small amounts of acid or base are added or on dilution.
15 of 123
An instrument for measuring the heat chnges that accompany chemical reactions.
16 of 123
A carbon with a positive charge.
17 of 123
A process in which the same amount of carbond dioxide is given out as taken in.
18 of 123
Asubstance that speeds up a reaction without being used up in the process.
19 of 123
Catalytic cracking
Using a catalyst to break long-chain hydrocarbons into shorter chain hydrocarbons
20 of 123
The process by which a monodentate ligand is replaces by a multidentate ligand in forming dative bonds to a transition metal.
21 of 123
Chemical feedstock
Starting material for an industrial chemical process.
22 of 123
Describes a molecule that exists as 2 non-superimposable isomers.
23 of 123
Chiral centre
An atom to which 4 different substituents are bonded.
24 of 123
Co-ordinate bond
A covalent bond in which both the electrons in the bond come from one of the atoms forming the bond.
25 of 123
Co-ordination number
Number of ligand molecules bonded to a metal ion.
26 of 123
Covalent bonding
The sharing of electrons between 2 non-metal atoms.
27 of 123
The spreading of electrons over several atoms to help them bond together.
28 of 123
Electrons spread over several atoms.
29 of 123
Dipole-dipole force
An intermolecular force that is caused by the attraction between molecules with permanent dipoles.
30 of 123
Displacement reaction
A reaction where an atome or group of atoms replaces another in a compund.
31 of 123
Displayed formula
Formula that is drawn out to show each atom and bond.
32 of 123
When the oxidation state of some atoms of a certain element is different on each side of a reaction.
33 of 123
Dynamic equilibrium
A situation in which the composition of a constant concentration reaction mixture doesn't change, as both forward and backward reactions are going at the same rate.
34 of 123
Electron density
Probability of electrons being found in a certain volume of space.
35 of 123
Electron pair repulsion theory
Explains the shapes of molecules. Pairs of electrons around a central atom repel each other and take up certain positions as far away from each other as possible.
36 of 123
The power of an atom to attract the electrons in a covalent bond.
37 of 123
An electron-deficient atom/ion/molecule that attacks areas of high electron density in another reactant.
38 of 123
Electrophilic addition
An electrophile attacking a C=C bond to saturate it.
39 of 123
Electrostatic forces
Forces of attraction/repulsion between electrically charged particles.
40 of 123
A reaction where an atom or group of atoms is removed from a reactant.
41 of 123
Empirical formula
Simplest whole number ratio of atoms of each element in a compound.
42 of 123
One pair of nonsuperimposable mirror image isomers.
43 of 123
When heat is taken in during a reaction, giving a positive enthalpy change and causing the temperature to drop.
44 of 123
End point
The point in a titration when the volume of reactant added causes a change in colour in the indicator.
45 of 123
Enthalpy change
A measure of heat energy transferred when a chemical/physical change takes place at a constant pressure.
46 of 123
Enthalpy diagrams
A diagram that shows enthalpy changes for reactions.
47 of 123
A numerical measure of disorder in a chemical system.
48 of 123
Equilibrium mixture
The mixture of reactants and products formed when a reversible reaction proceeds in a closed container until no further change occurs and the backward and forward reactions go at the same rate.
49 of 123
Equivalence point
The point in a titration at which the reaction is just complete.
50 of 123
When heat is given out during a reaction, giving a negative enthalpy change and causing the temperature to increase.
51 of 123
Fatty acid
A long chain carboxylic acid.
52 of 123
Fingerprint region
The area of an IR spectrum below about 1500cm^-1. This is caused by complex vibrations of a whole molecule - these vibrations are molecule-specific.
53 of 123
A mixture of hydrocarbons within the same range of boiling points, which are collected through the fractional distillation of crude oil.
54 of 123
Free radical
A highly reactive chemical species with an unpaired electron.
55 of 123
Functional group
An atom or group thereof in an organic molecule which is responsible for the characteristic reactions of that molecule.
56 of 123
Vertical column of elements in the periodic table, all with the same outer electron arrangement
57 of 123
Half equation
An equation showing the electrons transferred to/from one particular species in a redox reaction.
58 of 123
Homologous series
A set of organic compounds containing the same functional group.
59 of 123
When water is added to something to cause a reaction.
60 of 123
Hydrogen bonding
An intermolecular force in which a hydrogen atom interacts with a more electronegative atom (O, F, or N).
61 of 123
A reaction of a compund/ion with water.
62 of 123
Incomplete combustion
When there's not enough oxygen for all the carbon in the fuel to burn to carbon dioxide in a combustion reaction, therefore carbon monoxide and/or carbon (soot) are formed.
63 of 123
Inductive effect
Electron releasing effect of alkyl groups.
64 of 123
Ionic bonding
Electron/s being transferred from one atom to another, causing electrostatic forces of attraction between the opposing charges of the ion.
65 of 123
Ionisation energy
The energy required to remove a mole of electrons from a mole of atoms/ ions in the gaseous state.
66 of 123
1 of 2+ compound with the same molecular formula but a different arrangement in space.
67 of 123
An organic compound with an R-group on either side of a carbon atom with a C=O bond.
68 of 123
A regular 3D arrangement of atoms/ions/molecules.
69 of 123
Leaving group
In an organic substitution reaction, the leaving group is an atom or group thereof that's ejected from the starting material, normally taking an electron pair with it, thus forming a negative ion.
70 of 123
An atom/ion/molecule
71 of 123
Lone pair
A pair of outer shell electrons that isn't involved in bonding
72 of 123
Maxwell-Boltzmann distribution
Distribution of energies/speeds of the molecules in a gas/liquid.
73 of 123
Mean bond enthalpy
The average value of the bond dissociation enthalpy for a certain type of bond taken from a range of different compounds.
74 of 123
Metallic bonding
A bond caused by delocalised outer electrons from metal atoms being electrostatically attracted to the metal ions in the lattice holding it together.
75 of 123
A quantity of a substance containing 6.022x10^23 atoms/molecules.
76 of 123
Molecular formula
A fromula that tells you the actual number of atoms of each element in a molecule of a compound.
77 of 123
Molecular ion
An ionised molecule of sample in mass spectrometry, which has not been broken up during its flight through the instrument.
78 of 123
A small molecule that combines with many other monomers to make a polymer.
79 of 123
Sub-atomic particles in the nucleus of an atom (protons and neutrons).
80 of 123
An ion/group of molecules with a negative charge or partially negative area or a lone pair that takes part in an organic reaction by attackind electron-deficient areas in another reactant.
81 of 123
Nucleophilic substitution
When a nucleophile attacks a positively charged carbon atom in a molecule, replacing one of the groups/ atoms attached to the carbon in the original molecule.
82 of 123
The tiny positively-charged centre of an atom containing protons and neutrons.
83 of 123
Optical isomers
Pairs of molecules that are non-superimposable mirror images.
84 of 123
Order of reaction
The sum of the powers to which the concentrations of the species in a reaction are involved in the rate expression.
85 of 123
When an atom/group of atoms loses electrons in a reaction.
86 of 123
Oxidation state
Number of electrons lost/gained by an atom in compound compared to an uncombined atom.
87 of 123
Oxidising agent
A reagent that takes electrons from another species.
88 of 123
Percentage yield
Actual amount of product divided by the theoretical amount of product in a chemical reaction expressed as a percentage.
89 of 123
A horizontal row of elements in the periodic table.
90 of 123
The regular recurrence of properties of elements along a row of the periodic table.
91 of 123
A scale for meausing acidity and alkalinity. = -log(H+)
92 of 123
Describes a molecule in which the charge is unevenly spread, so that one area is more negatively charged than another.
93 of 123
Describes an atom/ion where the charge distribution around it is distorted from spherical.
94 of 123
Positive inductive effect
The tendency of some atoms or groups thereof to release electrons via covalent bonds.
95 of 123
Proton number
Same as the atomic number, it shows the number of protons in the nucleus of an atom.
96 of 123
Describes an atom/molecule/ion to which a proton has been added.
97 of 123
An optically inactive mixture of equal amounts of 2 optical isomers of a chiral compound.
98 of 123
Rate constant
The constant of proportionality in the rate expression.
99 of 123
Rate-determining step
The slowest step in the reaction mechanism.
100 of 123
Rate expression
Mathematical expression showing how the rate of a chemical reaction depends on the concentrations of various chemical species involved.
101 of 123
Reaction mechanism
The series of steps leading from reactants to products in a chemical reaction.
102 of 123
Redox reaction
Reduction-oxidation reaction; describes reactions in which electrons are transferred from one species to another.
103 of 123
Reducing agent
A reagent that adds electrons to another species.
104 of 123
When an atom or group thereof gains electrons.
105 of 123
Relative atomic mass
Average mass of an atom divided by one twelfth of the mass of one atom of carbon-12.
106 of 123
Relative formula mass
Average mass of an entity divided by one twelfth of the mass of one atom of carbon-12.
107 of 123
Relative molecular mass
Average mass of a molecule divided by one twelfth of the mass of one atom of carbon-12.
108 of 123
Saturated molecule
A compound containing only hydrogen and carbon, with only C-C and C-H bonds.
109 of 123
Specific heat capacity
The amount of heat required to raise the temperature of 1g of substance by 1K.
110 of 123
Spectator ions
Ions that don't get changed by a reaction because they don't actually play a part in it.
111 of 123
Standard molar enthalpy of combustion
The enthalpy change when 1 mole of a substance is completely burned in oxygen with all reactants in standard states and conditions.
112 of 123
Standard molar enthalpy change of combustion
The enthalpy change when 1 mole of substance is formed from its elements with all reactants being in standard states and conditions.
113 of 123
Isomers with the same molecular formula and structure, but a different position of the atoms in space.
114 of 123
Simple whole number ratios in which chemical species react.
115 of 123
Strong acid
An acid that is fully dissociated into ions in solution.
116 of 123
Strong nuclear force
The force that hold the subatomic particles in a nucleus together in a nucleus.
117 of 123
Structural formula
A way of writing the formula of an organic compound in which the bonds aren't shown, but each carbon atom is written separately.
118 of 123
Structural isomer
Isomers with the same molecular formula but a different structure.
119 of 123
Thermochemical cycle
A sequence of chemical reactions that convert a reactant into a product.
120 of 123
An ester formed between glycerol and 3 fatty acid molecules.
121 of 123
van der Waals force
A type of intermolecular force of attraction which is caused by instantaneous dipoles between atoms/molecules.
122 of 123
Weak acid
An acid that is only slightly dissociated into ions in solution.
123 of 123

Other cards in this set

Card 2


An organic compound related to a carboxylic acid of formula RCOZ, where Z=-Cl,-NHR,-OR or -OCOR


Acid derivative

Card 3


The minimum energy required by a particle to react. This is also the enthalpy change between the reactants and the transition state.


Preview of the back of card 3

Card 4


An organic compound with the general formula RCHO.


Preview of the back of card 4

Card 5


Metals in group 2 of the periodic table.


Preview of the back of card 5
View more cards


No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all All topics resources »