Definitions

Question 1

Isotopes

Answer 1

Atoms of the same element with different numbers of neutrons and different masses

Question 2

Relative isotopic mass

Answer 2

mass compared with 1/12th mass of carbon-12

Question 3

Relative atomic mass

Answer 3

weighted mean mass compared with 1/12th mass of carbon-12

Question 4

Ionic bonding

Answer 4

electrostatic attraction between positive and negative ions

Question 5

Covalent bond

Answer 5

strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 6

Electronegativity

Answer 6

the ability of an atom to attract the bonding electrons in a covalent bond

Question 7

Hydrogen bonding

Answer 7

intermolecular bonding between molecules containing N, O or F and the H atom of –NH, –OH or HF

Question 8

First ionisation energy

Answer 8

removal of 1 mol of electrons from 1 mol of gaseous atoms

Question 9

Disproportionation

Answer 9

oxidation and reduction of the same element

Question 10

enthalpy change of formation

Answer 10

formation of 1 mol of a compound from its elements

Question 11

enthalpy change of combustion

Answer 11

complete combustion of 1 mol of a substance

Question 12

enthalpy change of neutralisation

Answer 12

formation of 1 mol of water from neutralisation

Question 13

average bond enthalpy

Answer 13

as the breaking of 1 mol of bonds in gaseous molecules

Question 14

homologous series

Answer 14

a series of organic compounds having the same functional group but with each successive member differing by CH2

Question 15

structural isomers

Answer 15

compounds with the same molecular

formula but different structural formulae

Question 16

electrophile

Answer 16

an electron pair acceptor

Question 17

nucleophile

Answer 17

an electron pair donor

Question 18

Relative atomic mass

Answer 18

the weighted mean mass of an atom compared with 1/12th mass of an atom of carbon-12

Question 19

Relative isotopic mass

Answer 19

the mass of an atom of an isotope compared with 1/12th mass of an atom of carbon-12.

Question 20

Giant covalent lattice

Answer 20

network of atoms bonded by strong covalent bonds (e.g. carbon (diamond, graphite and graphene) and silicon)

Question 21

Heterolytic fission

Answer 21

when a covalent bond breaks, one bonding atom receives both electrons from the bonded pair.

Question 22

Homolytic fission

Answer 22

​when a covalent bond breaks, each bonding atom receives one electron from the bonding pair, forming 2 radicals.