Definitions

Question 1

Isotopes

Answer 1

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

Question 2

Atomic Structure

Answer 2

The numbers of protons, neutrons and electrons for atoms and ions, given the atomic number, mass number and any ionic charge.

Question 3

Relative Isotopic Mass

Answer 3

Weighted mean mass of an isotope compared to 1/12th mass of carbon 12.

Question 4

Relative Atomic Mass

Answer 4

Weighted mean mass of an atom compared with 1/12th mass of carbon-12.

Question 5

Empirical Formula

Answer 5

Simplest whole number ratio of atoms of each element present in a compound.

Question 6

Molecular Formula

Answer 6

The number and type of
atoms of each element in a molecule.

Question 7

Ionic Bonding

Answer 7

Electrostatic attraction between positive and negative ions.

Question 8

Covalent Bonding

Answer 8

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

Question 9

Metallic Bonding

Answer 9

Strong electrostatic
attraction between cations (positive ions)
and delocalised electrons.

Question 10

Average Bond Enthalpy

Answer 10

Measurement of covalent bond strength.

Question 11

Electronegativity

Answer 11

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

Question 12

First Ionisation Energy

Answer 12

Energy need to remove 1 mol of electrons from 1 mol of gaseous atoms.

Question 13

Second Ionisation Energy

Answer 13

Energy required to remove one mole of electrons from one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.

Question 14

General formula

Answer 14

The simplest algebraic
formula of a member of a homologous series.

Question 15

Structural formula

Answer 15

The minimal
detail that shows the arrangement of
atoms in a molecule

Question 16

Displayed formula

Answer 16

The relative positioning
of atoms and the bonds between them.

Question 17

Skeletal formula

Answer 17

The simplified organic
formula, shown by removing hydrogen
atoms from alkyl chains, leaving just a carbon skeleton and associated functional groups.

Question 18

Homologous series

Answer 18

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

Question 19

Functional group

Answer 19

A group of atoms
responsible for the characteristic reactions of a compound.

Question 20

Alkyl group

Answer 20

Formula CnH2n+1)

Question 21

Aliphatic

Answer 21

A compound containing carbon and hydrogen joined together in straight
chains, branched chains or non-aromatic rings.

Question 22

Alicyclic

Answer 22

An aliphatic compound arranged in non-aromatic rings with or without side
chains.

Question 23

Aromatic

Answer 23

A compound containing a
benzene ring.

Question 24

Saturated

Answer 24

Single carbon–carbon bonds only.

Question 25

Unsaturated

Answer 25

The presence of multiple carbon–carbon bonds and aromatic rings.

Question 26

Structural isomers

Answer 26

Compounds with the same molecular formula but different structural formulae.

Question 27

Homolytic fission

Answer 27

Each bonding atom receiving one electron from the bonded pair, forming two radicals.

Question 28

Heterolytic fission

Answer 28

One bonding atom receiving both electrons from the bonded pair

Question 29

Radical

Answer 29

A species with an unpaired electron.

Question 30

Curly arrow

Answer 30

The movement of an electron pair showing either heterolytic fission or formation of a covalent bond.

Question 31

Alkanes

Answer 31

Saturated hydrocarbons containing single C–C and C–H bonds as σ-bonds.

Question 32

(sigma) σ-bonds

Answer 32

Overlap of orbitals directly between the bonding atoms.