A Level Ocr Salters Chemistry Revision

Front 1

activation energy

Back 1

The minimum energy required to start a reaction by the breaking of bonds.

Front 2

addition polymer

Back 2

A very long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules (monomers).

Front 3

addition polymerisation

Back 3

The process in which unsaturated alkene molecules (monomers) add on to a growing polymer chain one at a time form a very long saturated molecular chain (the addition polymer).

Front 4

addition reaction

Back 4

A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.

Front 5

aliphatic hydrocarbon

Back 5

A hydrocarbon with carbon atoms joined together in straight or branched chains.

Front 6

alkyl group

Back 6

An alkane with a hydrogen atom removed, e.g. CH ,
C H ;alkyl groups are often shown as 'R'.

Front 7

atom economy

Back 7

molecular mass of the desired product
atom = x100
economy sum of molecular masses of all products

Front 8

average bond enthalpy

Back 8

The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species.

Front 9

bond enthalpy

Back 9

The enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species.

Front 10

carbocation

Back 10

An organic ion in whicha carbon atom has a positive charge.

Front 11

cis-trans isomerism

Back 11

A special type of ElZ isomerism in which there is a non-hydrogen group and a hydrogen atom on each C of a C=C double bond: The cis isomer (Z isomer) has the H atoms on each carbon on the same sid; the trans isomer (E isomer) has the H atoms on each carbon on different sides of the bond.

Front 12

compound

Back 12

A substance formed from two or more chemically bonded elements in a fixed ratio, usually shown by a chemical formula.

Front 13

concentration

Back 13

The amount of solute, in mol, per 1 dm (1000 cm ) of solution.

Front 14

coordinate bond

Back 14

A shared pair of electrons which has been provided by one of the bonding atoms only; also called a dative covalent bond.

Front 15

curly arrow

Back 15

A symbol used in reaction mechanisms to show the movement of an electron pair in the breaking or formation of a covalent bond.

Front 16

dehyration

Back 16

An elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule.

Front 17

displacement reation

Back 17

A reaction in which a more reactive element displaces a less reactive element from an aqueous solution of the latter's ions.

Front 18

displayed formula

Back 18

A formula showing the relative positioning of all the atoms in a molecule and the bonds between them.

Front 19

dynamic equilibrium

Back 19

The equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction.

Front 20

E/Z isomerism

Back 20

A type of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted rotation of the C=C bond.

Front 21

electron configuration

Back 21

The arrangement of electrons in an atom.

Remember the use of subshells 1s2, 2s2, 2p6...

Front 22

electrophile

Back 22

An atom (or group of atoms) that is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond.

Front 23

electrophilic addition

Back 23

A type of addition reaction in which an electrophile is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond.

Front 24

elimination reaction

Back 24

The removal of a molecule from a saturated molecule to make an unsaturated molecule.

Front 25

endothermic reaction

Back 25

A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings ( H+ve).

Front 26

enthalpy, H

Back 26

The heat content that is stored in a chemical system.

Front 27

(standard) enthalpy change of combustion, H

Back 27

The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all reactants and products being in their standard states.

Front 28

(standard) enthalpy change of formation, H

Back 28

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

Front 29

(standard) enthalpy change of reaction, H

Back 29

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.

Front 30

enthalpy cycle

Back 30

A diagram showing alternative routes between reactants and products which allows the indirect determination of a enthalpy change from other known enthalpy changes using Hess' law.

Front 31

enthalpy profile diagram

Back 31

A diagram for a reaction to compare the enthalpy of the reactants with the enthalpy of the products.

Front 32

esterification

Back 32

The reaction of an alcohol with a carboxylic acid to produce an ester and water.

Front 33

exothermic reaction

Back 33

A reaction in which the enthalpy of the products is smaller that the enthalpy of the reactants, resulting in heat loss to the surroundings ( H-ve).

Front 34

fragmentation

Back 34

The process in mass spectrometry that causes a positive ion to split into pieces, one of which is a positive fragment ion.

Front 35

functional group

Back 35

The part of the organic molecule responsible for its chemical reactions.

Front 36

general formula

Back 36

The simplest algebraic formula of a member of a homologous series. For example, the general formula of the alkanes is C H

Front 37

giant covalent lattice

Back 37

A three-dimensional structure of atoms, bonded together by strong covalent bonds.

Front 38

giant ionic lattice

Back 38

A three-dimensional structure of oppositely charged ions, bonded together by strong ionic bonds.

Front 39

giant metallic lattice

Back 39

A three-dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds.

Front 40

greenhouse effect

Back 40

The process in which the absorption and subsequent emission of infrared radiation by atmospheric gases warms the lower atmosphere and the planet's surface.

Front 41

group

Back 41

A vertical column in the Periodic Table. Elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons.

Front 42

Hess' law

Back 42

If a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route.

Front 43

heterogeneous catalysis

Back 43

A reaction in which the catalyst has a different physical state from the reactants; frequently, reactants are gases whilst the catalyst is a solid.

Front 44

homogeneous catalysis

Back 44

A reaction in which the catalyst and reactants are in the same physical state, which is most frequently the aqueous or gaseous state.

Front 45

homologous series

Back 45

A series of organic compounds with the same functional group, but with each successive member differing by CH .

Front 46

hydrated

Back 46

Crystalline and containing water molecules.

Front 47

hydrogen bond

Back 47

A strong dipole-dipole attraction between an electron-deficient hydrogen atom (O-H or N-H ) on one molecule and a lone pair of electrons on a highly electronegative atom (H-O: or H-N: ) on a different molecule.

Front 48

initiation

Back 48

The first step in a radical substitution in which the free radicals are generated by ultraviolet radiation.

Front 49

intermolecular force

Back 49

An attractive force between neighbouring molecules. Intermolecular forces can be van der Waals' forces (induced dipole-dipole forces), permanent dipole-dipole forces or hydrogen bonds.

Front 50

ion

Back 50

A positively or negatively charge atom or (covalently bonded) group of atoms (a molecular ion).

Front 51

ionic bonding

Back 51

The electrostatic attraction between oppositely charged ions.

Front 52

(first) ionisation energy

Back 52

The energy required to remove one mole of electrons in one mole of gaseous 1 + ions to form one mole of gaseous 1 + ions.

Front 53

(second) ionisation energy

Back 53

The energy required to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

Front 54

(successive) ionisation energy

Back 54

A measure of the energy required to remove each electron in turn, e.g. the second ionisation energy is the energy required to remove one electron from each ion in one mole of gaseous 1+ ions to from one mole of gaseous 2+ ions.

Front 55

le Chatelier's principle

Back 55

When a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change.

Front 56

limiting reagent

Back 56

The substance in a chemical reaction that runs out first.

Front 57

mechanism

Back 57

A sequence of steps showing the path taken by electrons in a reaction.

Front 58

metallic bond

Back 58

The electrostatic attraction between positive metal ions and delocalised electrons.

Front 59

molecular ion, M+

Back 59

The positive ion formed in mass spectrometry when a molecule loses an electron.

Front 60

nucleophile

Back 60

An atom (or group of atoms) that is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.

Front 61

necleophilic substitution

Back 61

A type of substitution reaction in which a nucleophile is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.

Front 62

oxidising agent

Back 62

A reagent that oxidises (takes electrons from) another species.

Front 63

percentage yield

Back 63

actual amount, in mol, of product
% ---------------------------------------------- x100
yield = theoretical amount, in mol, of product

Front 64

period

Back 64

A horizontal row of elements in the Periodic Table. Elements show trends in properties across a period.

Front 65

Permanent dipole

Back 65

A small charge difference across a bond resulting from a difference in electronegativities of the bonded atoms.

Front 66

permanent dipole-dipole force

Back 66

An attractive force between permanent dipoles in neighbouring polar molecules.

Front 67

polar covalent bond

Back 67

A bond with permanent dipole.

Front 68

polar molecule

Back 68

A molecule with an overall dipole, taking into account any dipoles across bonds.

Front 69

precipitation reaction

Back 69

The formation of a solid from a solution during a chemical reaction. Precipitates are often formed when two aqueous solutions are mixed together.

Front 70

propagation

Back 70

The two repeated steps in radical substitution that build up the products in a chain reaction.

Front 71

radical

Back 71

A species with an unpaired electron.

Front 72

rate of reaction

Back 72

The change in concentration of a reactant or a product in a given time.

Front 73

reducing agent

Back 73

A reagent that reduces (adds electron to) another species.

Front 74

reflux

Back 74

The continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the contents of the flask boiling dry.

Front 75

repeat unit

Back 75

A specific arrangement of atoms that occurs in the structure over and over again. Repeat units are included in brackets, outside of which is the symbol n.

Front 76

salt

Back 76

A chemical compound formed from an acid, when a H+ ion from the acid has been replaced by a metal ion or another positive ion, such as the ammonium ion, NH +.

Front 77

shell

Back 77

A group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level.

Front 78

simple molecular lattice

Back 78

A three-dimensional structure of molecules, bonded together by weak intermolecular forces.

Front 79

skeletal formula

Back 79

A simplified organic formula, with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups.

Front 80

specific heat capacity, c

Back 80

The energy required to raise the temperature of l g of a substance by l C.

Front 81

spectator ions

Back 81

Ions that are present but take no part in a chemical reaction.

Front 82

standard conditions

Back 82

A pressure of 100 kPa (1 atmosphere), a stated temperature usually 298 K (25 C), and a concentration of 1 mol dm (for reactions with aqueous solutions).

Front 83

standard solution

Back 83

A solution of known concentration. Standard solutions are normally used in titrations to determine unknown information about another substance.

Front 84

standard state

Back 84

The physical state of a substance under the standard conditions of 100 kPa (1 atmosphere) and 298 K (25 C).

Front 85

stereoisomers

Back 85

Compounds with the same structural formula but with a different arrangement of the atoms in space.

Front 86

structural isomers

Back 86

Molecules with the same molecular formula but with different structural arrangements of atoms.

Front 87

substitution reaction

Back 87

A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.

Front 88

thermal decomposition

Back 88

The breaking up of a chemical substance with heat into at least two chemical substances.

Front 89

volatility

Back 89

The ease that a liquid turns into a gas. Volatility increases as boiling point decreases.

Front 90

ligand

Back 90

tbc

Front 91

DNA

Back 91

tbc

Front 92

elecrode potenitals

Back 92

tbc

Front 93

rusting of iron

Back 93

tbc

Front 94

complex ions

Back 94

tbc

Front 95

transition metal features

Front 96

transition metal ions and percipitates formed

Back 96

tbc

Front 97

acylation

Back 97

tbc

Front 98

protein

Back 98

tbc

Front 99

amino acid

Back 99

tbc

Front 100

zwitterion forms

Back 100

tbc

Front 101

lattice enthaply

Back 101

tbc

Front 102

enthaply of hydration

Back 102

tbc

Front 103

buffer solution

Back 103

tbc

Front 104

entropy

Back 104

tbc

Front 105

enthalpy change of solution

Back 105

tbc

Front 106

enthalpy change of salvation

Back 106

tbc

Front 107

redox

Back 107

tbc