Definitions Term 1

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 12g of carbon-12

Question 3

Mole

Answer 3

The amount of a substance of which contains the Avogadro’s constant of atoms molecules or a group of ions.

Question 4

Molar mass

Answer 4

The mass of one mole of a substance

Question 5

Anhydrous salt

Answer 5

Salt without WOC

Question 6

Hydrated salt

Answer 6

Salt with WOC

Question 7

Water of crystalisation

Answer 7

Water chemically bonded in a crystal structure

Question 8

Atomic number

Answer 8

Number of protons in an atom

Question 9

mass number

Answer 9

Number of protons and neutrons in the nuclei of an atom

Question 10

Relative atomic mass

Answer 10

(RAM) The average (weighted mean) mass of an atom of an element relative to one-twelfth of the mass of an atom of carbon-12.

Question 11

Relative isotopic mass

Answer 11

(RIM) The mass of an atom of an isotope of an element relative to one-twelfth of the mass of an atom of carbon-12.

Question 12

Isotopes

Answer 12

Atoms with same number of protons but a different number of neutrons.

Question 13

Relative formula mass

Answer 13

(RFM) The average (weighted mean) mass of a formula unit relative to one-twelfth of the mass of an atom of carbon-12.

Question 14

Relative molecular mass

Answer 14

(RMM) The average (weighted mean) mass of a molecule relative to one-twelfth of 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 gaseous ions with a triple positive charge.

Question 18

Covalent bond

Answer 18

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

Question 19

Octet rule

Answer 19

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

Question 20

Electronegativity

Answer 20

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

Question 21

Polar bond

Answer 21

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

Question 22

Delocalised electrons

Answer 22

Outer electrons do not have fixed positions but move freely.

Question 23

Intermolecular

Answer 23

Between neighbouring molecules (as opposed to intramolecular)

Question 24

Van der Wall’s

Answer 24

forces The attraction between instantaneous and induced dipoles on neighbouring molecules.

Question 25

Permanent dipole-dipole attractions

Answer 25

Attraction between the positive end, δ+, of the permanent dipole on a molecule with the negative end, δ-, of the permanent dipole of a neighbouring molecule.

Question 26

Hydrogen bond

Answer 26

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

Question 27

Redox

Answer 27

Oxidation and reduction occur in the same reaction

Question 28

Oxidation

Answer 28

Loss of electrons/Increase in oxidation state.

Question 29

Reduction

Answer 29

Gain of electrons/Decrease in oxidation state.

Question 30

Oxidising agent

Answer 30

Electron acceptor

Question 31

Disproportionation

Answer 31

Oxidation and reduction of the same element in the same reaction.

Question 32

Co-ordinate bond

Answer 32

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

Question 33

Reducing agent

Answer 33

Electron donor

Question 34

Strong acid/base

Answer 34

Full dissociates in solution

Question 35

Weak acid/base

Answer 35

Partially dissociates in solution

Question 36

Molarity

Answer 36

Concentration in mol dm-3 expressed using M

Question 37

Concentration

Answer 37

Number of moles or mass stated in a present soloution

Question 38

Standard solution

Answer 38

A solution for which the concentration is known