Definitions

Question 1

Molecular ion

Answer 1

Two or more atoms covalently bonded with an overall charge

Question 2

Avogadro’s constant

Answer 2

Number of atoms in 12.000g of carbon-12

Question 3

Mole

Answer 3

The amount of substance which contains the Avogadro constant of atoms, molecules or groups of ions

Question 4

Molar mass

Answer 4

The mass of one mole of a substance

Question 5

Anhydrous

Answer 5

A salt which contains no water of crytallisation

Question 6

Hydrated

Answer 6

A salt which contains water of crystallisation

Question 7

Water of crystallisation

Answer 7

Water chemically bonded within a crystal structure

Question 8

Atomic number

Answer 8

The number of protons in an atom

Question 9

Mass number

Answer 9

The total number of protons and neutrons in an atom

Question 10

Relative atomic mass

Answer 10

The average mass of an atom of an element relative to one-twelfth the mass of an atom of carbon-12

Question 11

Relative isotopic mass

Answer 11

The mass of an atom of an isotope of an element relative to one-twelfth the mass of an atom of carbon-12

Question 12

Isotopes

Answer 12

Atoms that have the same atomic number but a different mass number

Question 13

Relative Formula Mass

Answer 13

The average mass of a formula unit relative to one-twelfth the mass of an atom of carbon-12

Question 14

Relative molecular mass

Answer 14

The average mass of a molecule relative to one-twelfth the mass of an atom of carbon-12

Question 15

First ionisation energy

Answer 15

The energy required to convert one mole of gaseous atoms into gaseous ions with a single positive charge

Question 16

Second ionisation energy

Answer 16

The energy required to convert one mole of gaseous ions with a single positive charge into gaseous ions with a double positive charge

Question 17

Third ionisation energy

Answer 17

The energy required to convert one mole of gaseous ions with a double positive charge into one mole of gaseous ions with a triple positive charge

Question 18

Covalent bond

Answer 18

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

Question 19

Co-ordinate bond

Answer 19

A shared pair of electrons between two atoms. One atom provides both electrons

Question 20

Octet rule

Answer 20

When reacting, an atom tends to gain, lose or share electrons to achieve eight in its outer shell

Question 21

Electronegativity

Answer 21

The extent to which an atom attracts the bonding electrons in a covalent bond

Question 22

Polar bond

Answer 22

A covalent bond in which there is unequal sharing of the bonding electrons

Question 23

Delocalised electrons

Answer 23

Outer electrons do not have fixed positions but move freely

Question 24

Intermolecular

Answer 24

Between neighbouring molecules

Question 25

Van der Waals forces

Answer 25

The attraction between instantaneous and induced dipoles on neighbouring molecules

Question 26

Permanent dipole-dipole attraction

Answer 26

The attraction between the positive end, 𝞭+, of the permanent dipole on a molecule and the negative end, 𝞭-, of the permanent dipole on a neighbouring molecule.

Question 27

Hydrogen bond

Answer 27

The attraction between a lone pair of electrons on a very electronegative atom (N, O or F) in one molecule and a hydrogen atom of a neighbouring molecule, in which the hydrogen atom is covalently bonded to a very electronegative atom (N,O or F)

Question 28

Redox

Answer 28

Oxidation and reduction occur in the same reaction

Question 29

Oxidation

Answer 29

Loss of electrons / Increase in oxidation state

Question 30

Reduction

Answer 30

Gain of electrons / Decrease in oxidation state

Question 31

Oxidising agent

Answer 31

Electron acceptor

Question 32

Reducing agent

Answer 32

Electron donor

Question 33

Disproportionation

Answer 33

Oxidation and reduction of the same element in the same reaction

Question 34

Strong acid/base

Answer 34

Fully dissociates in solution

Question 35

Weak acid/base

Answer 35

Partially dissociates in solution

Question 36

Molarity

Answer 36

Concentration in moldm-3, expressed as M

Question 37

Standard solution

Answer 37

A solution of known concentration