Definitions

Question 1

Relative isotopic mass

Answer 1

The weighted average mass of one atom of an isotope compared with 1/12th of the mass of an atom of the isotope of carbon-12

Question 2

Relative atomic mass

Answer 2

The weighted average mass of an element compared with 1/12th of the mass of an atom of carbon-12

Question 3

First ionisation energy

Answer 3

The energy required to remove an electron from one mole of gaseous atoms to form one mole of gaseous +1 ions

Question 4

Periodicity

Answer 4

A repeating trend or pattern across different periods

Question 5

Orbital

Answer 5

A region where there is a high probability of finding an electron

Question 6

Ionic bond

Answer 6

Electrostatic attraction between two oppositely charged ions

Question 7

Covalent bond

Answer 7

Electrostatic attraction between two positive nuclei and a shared pair of electron

Question 8

Electron pair repulsion theory

Answer 8

Electron pairs in the outer shell arrange themselves to maximise separation and minimise repulsion

Question 9

Hydrogen bond

Answer 9

Intermolecular force of attraction between an electron deficient hydrogen (bonded to an element more electronegative than itself) and the lone pair of electrons on an electronegative atom in another molecule

Question 10

Allotrope

Answer 10

Different forms of the same element in the same physical state

Question 11

Electronegativity

Answer 11

The ability of an atom to attract a shared pair of electrons in a covalent

Question 12

Instantaneous dipole-induced dipole interactions (London forces)

Answer 12

At a single point in time, the electron density around a molecule will not be symmetrical. One side has more electron density causing an instantaneous dipole and this induced a dipole in a nearby molecule which can attract to the instantaneous dipole

Question 13

Disproportionation

Answer 13

When a single element is simultaneously oxidised and reduced in a single reaction

Question 14

Empirical formula

Answer 14

The simplest whole number ratio of atoms of each element in a compound

Question 15

Molecular formula

Answer 15

The actual number of atoms of each element in one molecule

Question 16

Homologous series

Answer 16

A family of compounds which all contain the same functional group and each member of the series contains one more CH2 than the previous

Question 17

Functional group

Answer 17

Part of the molecule responsible for the chemical reaction

Question 18

Structural isomerism

Answer 18

Compounds with the same molecular formula but different structural and displayed

Question 19

Stereoisomerism

Answer 19

Molecules with the same structural formula but the atoms are arranged differently in a space

Question 20

Radical

Answer 20

Species with an impaired electron

Question 21

Electrophile

Answer 21

Electron pair acceptor

Question 22

Nucleophile

Answer 22

An electron pair donor

Question 23

Standard enthalpy change of reaction

Answer 23

Enthalpy change when the number of substances in the equation as written react (100kPa)

Question 24

Enthalpy change of formation

Answer 24

Enthalpy change when one mole of substances is formed from its constituent elements (100kPa)

Question 25

Enthalpy change of combustion

Answer 25

Enthalpy change when one mole of substance is completely in oxygen (100kPa)

Question 26

Enthalpy change of neutralisation

Answer 26

Enthalpy change when one mole of water is produced by neutralisation of an acid with a base (100kPa)

Question 27

Hess’s Law

Answer 27

Enthalpy change of a reaction is independent of the oath taken provided that the individual and final conditions are the same

Question 28

Bond enthalpy

Answer 28

Enthalpy change when one mole of a bond in the gaseous state is broken