Definitions

Question 1

Atomic number (z)

Answer 1

the number of protons in the nucleus of an atom

Question 2

Mass number (a)

Answer 2

the total number or protons and neutrons in the nucleus of an atom

Question 3

Relative isotopic mass (RIM)

Answer 3

the mass of an atom of a particular isotope of an element, relative to 1/12th the mass of a carbon-12 atom

Question 4

Relative atomic mass (RAM, Ar)

Answer 4

the average mass of an atom of an element, relative to 1/12th the mass of a carbon-12 atom

Question 5

Orbital

Answer 5

a region of 3D in which there is a probability of finding an electron

Question 6

1st ionisation energy

Answer 6

energy required to remove one electron from each atom, in a mole of gaseous atoms

Question 7

2nd ionisation energy

Answer 7

energy required to remove one electron from each 1+ ion, in a mole of gaseous 1+ ions

Question 8

Periodicity

Answer 8

trends in the properties of elements repeat in successive periods of the periodic table

Question 9

Electronegativity

Answer 9

the ability of an atom of an element to attract a pair of bonding electrons

Question 10

Oxidised

Answer 10

loss of electrons and increase in oxidation number

Question 11

Reduced

Answer 11

gain of electrons and decrease in oxidation number

Question 12

Oxidising agent

Answer 12

causes oxidation by taking away electrons

Question 13

Reducing agent

Answer 13

causes reduction by giving electrons

Question 14

Hess’s law

Answer 14

ΔH for a reaction is independent of the route taken

Question 15

Standard enthalpy of formation

Answer 15

enthalpy change when one mole of a substance is formed from its elements in their standard states at 298K and 100kPa

Question 16

Standard enthalpy of combustion

Answer 16

enthalpy change when one mole of a substance is completely oxidised in excess oxygen at standard conditions 298K and 100kPa

Question 17

Why do we do Hess cycles

Answer 17

when it requires heat energy and we cant measure temp change

Question 18

Mole

Answer 18

the amount of any substance which occupies a volume of 24dm3 at room temp and pressure

Question 19

Avogadros number

Answer 19

the number of things in a mole

Question 20

Ionic bonding

Answer 20

the electrostatic attraction between oppositely charged ions in all directions

Question 21

Anions

Answer 21

negative ions

Question 22

Cations

Answer 22

positive ions

Question 23

Covalent bonding

Answer 23

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

Question 24

Dative bond

Answer 24

is a covalent bond where only one of the bonded atoms donated both electrons being shared

Question 25

Symmetrical molecule

Answer 25

all the atoms around the central atom are the same and there are no lone pairs on the central atom

Question 26

Unsymmetrical molecule

Answer 26

the central atom has two or more different atoms or the central atoms has one or more lone pairs

Question 27

Disproportionation

Answer 27

A reaction where one element in one species is both oxidised and reduced

Question 28

Lattice energy (LE)

Answer 28

Energy released when one mole of an ionic compound is formed from gaseous ions

Question 29

Standard enthalpy of hydration

Answer 29

Enthalpy change when one mole of gaseous ions are hydrated by excess water

Question 30

Standard enthalpy of solution

Answer 30

Enthalpy change when on mole of ionic solid dissolves in excess water

Question 31

What is entropy

Answer 31

A measure of the amount of disorder

Question 32

Rate or reaction

Answer 32

Change in quantity of reactant or product over time

Question 33

Activation energy

Answer 33

The minimum energy required for a collision to be successful

Question 34

Homogenous catalyst

Answer 34

Catalyst is in the same state/phase as the reactants

Question 35

Heterogenous catalyst

Answer 35

The catalyst is in a different phase from reactants

Question 36

Adsorption

Answer 36

A process in which atoms, molecules or ions are held on the surface of the solid

Question 37

Desorption

Answer 37

Removal of an adsorbed molecule, atom or ion from an adsorbent

Question 38

Half life

Answer 38

Time taken for the concentration of reaction to halve

Question 39

Chiral molecule

Answer 39

A molecule containing a carbon atom which has four different groups bonded to it

Question 40

Stability constant Kstab

Answer 40

The equilibrium constant for the formation of a complex ion in a solvent from its constituent ions

Question 41

Large Kstab

Answer 41

stable complex

Question 42

Small Kstab

Answer 42

unstable complex

Question 43

Standard electrode potential

Answer 43

- The emf of a half cell measured relative to the standard hydrogen electrode - All solutions at 1moldm-3 concentration and gases at 100kPa - At 298 K

Question 44

Lattice enthalpy of formation

Answer 44

Enthalpy change when: - 1 mole of a solid ionic compound is formed - from its gaseous ions - under standard conditions

Question 45

Enthalpy change of atomisation

Answer 45

Enthalpy change when: - 1 mole of gaseous atoms is made - from an element - in its standard state

Question 46

Enthalpy change of solution

Answer 46

Enthalpy change when: - 1 mole of an ionic substance is dissolved in the minimum amount of solvent - to ensure no further enthalpy change is observed upon further dilution