Key Definitions 1.1

Question 0

An ion

Answer 0

A positively or negatively charged atom or group of atoms

Question 1

Isotopes

Answer 1

Atoms of the same element with different numbers of neutrons

Question 2

Relative isotopic mass

Answer 2

The mass of an atom of an isotope compared to 1/12 the mass of an atom of carbon-12

Question 3

Relative atomic mass

Answer 3

The weighted mean mass of an atom of an element compared to one twelfth of the mass of an atom of carbon-12

Question 4

Relative molecular mass

Answer 4

The weighted mean mass of a molecule compared to 1/12 the mass of an atom of C-12

Question 5

Relative formula mass

Answer 5

The weighted mean mass of a formula unit compared to 1/12 the mass of an atom of c-12

Question 6

Amount of substance

Answer 6

A quantity with the unit mole

Question 7

The Avogadro constant

Answer 7

The number of atoms per mole of C-12

Question 8

A Mole

Answer 8

The amount of any substance containing as many particles as there are carbon a atoms in 12g of carbon-12

Question 9

Molar mass

Answer 9

Mass per mole of a substance

G/mol^-1

Question 10

Empirical formula

Answer 10

The simplest whole number ratio of each element in a compound

Question 11

Molecule

Answer 11

Small group of atoms bonded together by covalent bonds

Question 12

Molecular formula

Answer 12

The actual number of each element present in a molecule

Question 13

Molar volume

Answer 13

The volume per mole of a gas

Dm^3 mol^-1

Question 14

Concentration

Answer 14

The amount of solute per mole dissolved per dm^3 of solution

Question 15

Standard solution

Answer 15

A solution of known concentration

Question 16

A species

Answer 16

Any type of particle that takes part in a chemical reaction

Question 17

Stoichiometry

Answer 17

The molar relationship between the relative quantities of substances taking part in a reaction

Question 18

Acid

Answer 18

A species that is a proton donor

Question 19

A base

Answer 19

A species that is a proton acceptor

Question 20

An alkali

Answer 20

A type of base that dissolves in water forming hydroxide ions

Question 21

A salt

Answer 21

Any chemical compound formed from an acid where the H+ ion has been replaced by a metal ion

Question 22

A cation

Answer 22

Positively charged ion

Question 23

Anion

Answer 23

A negatively charged ion

Question 24

Hydrated

Answer 24

A crystalline compound contains water molecules

Question 25

Anhydrous

Answer 25

A substance that contains no water molecules

Question 26

Water of crystallisation

Answer 26

Refers to the water molecules that form an essential part of the crystalline structure of a compound

Question 27

Oxidation number

Answer 27

A measure of electrons that an atom uses to bond with atoms of another element.

Question 28

Oxidation

Answer 28

Loss of electrons

Increase in oxidation number

Question 29

Reduction

Answer 29

Gain of electrons

Decrease in oxidation number

Question 30

A redox reaction

Answer 30

A reaction which involves both reduction and oxidation

Question 31

A reducing agent

Answer 31

A reagent that reduces another species (adds electrons)

Question 32

Oxidising agent

Answer 32

A species that oxidises another species

Takes electrons from