Key definitions

Question 1

Ionic bonding

Answer 1

Electrostatic force of attraction
between positives ions
& negative ions

Question 2

Covalent bonding

Answer 2

Electrostatic force of attraction
between a shared pair of electrons
& the nuclei of the bonded atoms

Question 3

Dative covalent bonding

Answer 3

Shared pair of electrons
has been supplied
by one of the
bonding atoms only

Question 4

Metallic bonding

Answer 4

Electrostatic force of attraction
between metal ions
& delocalised electrons

Question 5

d-block elements

Answer 5

An element
with its highest energy electron
in a d-subshell

Question 6

Transition metals

Answer 6

A d-block element
that forms at least
one ion with
an incomplete d-subshell

Question 7

Complex ion

Answer 7

A central metal ion
surrounded by ligands

Question 8

Ligand

Answer 8

A molecule or ion
that donates a pair of electrons
to a central metal ion
forming a coordinate bond

Question 9

Monodentate ligand

Answer 9

A ligand
that donates one pair of electron
to a central metal ion
to form one coordinate bond

Question 10

Bidentate ligand

Answer 10

A ligand
that can donate
two lone pairs of electrons
to a central metal ion
to form two coordinate bonds

Question 11

Optical isomerism

Answer 11

Two isomers that are
non-superimposable
mirror images
of each other

Question 12

Le Chatelier

Answer 12

When a system in dynamic equilibrium is subjected to change,
the position of equilibrium
will shift to minimise the change

Question 13

Acid definition

Answer 13

A proton donor in aqueous solution

Question 14

Strong acid

Answer 14

Fully dissociated in aqueous solution

Question 15

Weak acid

Answer 15

Partially dissociated
in aqueous solution

Question 16

Base definition

Answer 16

A proton acceptor

Question 17

Alkali definition

Answer 17

A soluble base
that dissolves in water
to produce hydroxide ions

Question 18

Salt definition

Answer 18

Formed when hydrogen ions from an acid
are replaced by metal/ammonium ions

Question 19

Hydrated

Answer 19

A crystalline compound
that contains water molecules

Question 20

Anhydrous

Answer 20

A substance that contains
no water molecules

Question 21

Water of crystallisation

Answer 21

Water molecules that form an essential part of the crystalline structure

Question 22

Acid-base pair

Answer 22

A pair of species that transform into each other by gain or loss of a proton

Question 23

Buffer

Answer 23

A mixture that
minimises pH change
on addition of
small amounts of
acid or base

Question 24

Standard enthalpy change of combustion

Answer 24

The enthalpy change when
one mole of a substance
reacts completely with oxygen
under standard conditions

Question 25

Standard enthalpy change of formation

Answer 25

The enthalpy change when
one mole of a compound
is formed from it constituent elements
in their standard state

ΔH=-ve

Question 26

Standard enthalpy change of neutralisation

Answer 26

The enthalpy change when
an aqueous acid
is neutralised
by an aqueous base
to form one mole of water
under standard conditions

It is a constant (-57 kJmol-1)

Question 27

Standard enthalpy change of reaction

Answer 27

The enthalpy change when
a reaction occurs
in the molar quantities expressed
in a chemical equation
under standard conditions

Question 28

Bond enthalpy

Answer 28

The enthalpy change
when one mole of bonds
are broken
in gaseous species at 298K

Question 29

Hess’s law

Answer 29

If a reaction can take place
by more than one route
and the initial and final conditions
are the same
the total enthalpy change is the same

Question 30

Lattice enthalpy

Answer 30

The enthalpy change
for the formation of
one mole of an ionic compound
from its gaseous ions
under standard conditions

ΔH=-ve

Question 31

Enthalpy change of solution

Answer 31

The enthalpy change when
one mole of a solid
dissolves in a solvent
under standard conditions

Exothermic or endothermic

Question 32

Enthalpy change of hydration

Answer 32

The enthalpy change
when gaseous ions
dissolve in water
to form one mole of
aqueous ions

ΔH=-ve

Question 33

Enthalpy change of atomisation

Answer 33

The enthalpy change
when one mole of
atoms in gaseous state
is formed from the element
in its standard state

ΔH=+ve - bonds have to be broken

Question 34

First electron affinity

Answer 34

The enthalpy change when
one mole of gaseous atoms
each gain one electron

ΔH=-ve

Question 35

First ionisation energy (enthalpy)

Answer 35

The enthalpy change
when one mole of
gaseous 1+ ions
are formed from
one mole of gaseous atoms

ΔH=+ve

Question 36

Entropy

Answer 36

The quantitative measure of
the degree of disorder
in a system

Question 37

Electronegativity

Answer 37

Ability of an atom
to attract the
bonding pair of electrons
in a covalent bond

Question 38

First ionisation energy (periodicity)

Answer 38

The energy required
to remove 1 electron
from each atom
in 1 mole of gaseous atoms
to form 1 mole of
gaseous 1+ ions

Question 39

Standard electrode potential

Answer 39

The e.m.f. of a half cell
when connected to a
standard hydrogen half cell
under standard conditions

298K, 100kPa, solutions 1moldm-3

Question 40

Fuel cell definition

Answer 40

A fuel cell
produces voltage
from the continuous reaction
of a fuel with oxygen

(O & fuel must be continuously supplied)

Question 41

Rate of reaction

Answer 41

The change in concentration
of reactants or products
overtime

Question 42

Catalyst

Answer 42

A substance that provides
an alternative reaction route
of lower activation energy

Question 43

Half life

Answer 43

The time taken
for the concentration
of the reactants
to be reduced by a half

Question 44

Rate determining step

Answer 44

The slowest step
in the reaction mechanism
of a multi-step reaction

Question 45

Isotope

Answer 45

Atoms of the same element
with the same no. proton
but different no. neutrons

Question 46

Relative isotopic mass

Answer 46

The mass of an atom of an isotope
compared with
1/12 the mass of an atom of
Carbon-12

Question 47

Relative atomic mass

Answer 47

The weighted mean mass
of an atom of an element
compared with 1/12
the mass of Carbon-12