Definitions ALL

Question 1

First ionisation energy

Answer 1

Enthalpy change when one mole of electrons are removed from one mole of gaseous atoms

Question 2

Relative atomic mass

Answer 2

Average mass of an atom, relative to 1/12th the mass of the carbon-12 isotope

Question 3

Empirical formula

Answer 3

Simplest ratio of elements in a compound

Question 4

Relative molecular mass

Answer 4

Average mass of a molecule, relative to 1/12th the mass of the carbon-12 isotope

Question 5

Atom economy

Answer 5

Molecular mass of desired product/sum of molecular masses of all reactants

Question 6

Dative bonding

Answer 6

Bonding where one atom provides both of an electron pair to another atom

Question 7

Electronegativity

Answer 7

The power of an atom to attract the bonded pair of electrons toward itself

Question 8

Enthalpy change

Answer 8

Energy change under constant pressure

Question 9

Standard conditions

Answer 9

298K and 100kPa

Question 10

Standard enthalpy of formation

Answer 10

Enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions

Question 11

Standard enthalpy of combustion

Answer 11

Enthalpy change when one mole of a compound is burned completely in excess oxygen under standard conditions

Question 12

Hess’ Law

Answer 12

Enthalpy change is constant, regardless of the path taken

Question 13

Bond dissociation enthalpy

Answer 13

Enthalpy change when one mole of a bond is broken to give gaseous atoms

Question 14

Mean bond enthalpy

Answer 14

Enthalpy change when one mole of a bond is broken, averaged over different compounds

Question 15

Activation energy

Answer 15

Energy required for a reaction to occur

Question 16

Catalyst

Answer 16

A chemical that speeds up a reaction by providing a different pathway with a lower activation energy

Question 17

Dynamic equilibrium

Answer 17

Forward rate = Backward rate. Moles of reactants and products are constant

Question 18

Disproportionation

Answer 18

A reaction in which a substance is simultaneously oxidised and reduced

Question 19

Homologous series

Answer 19

A family of hydrocarbons with similar chemical properties who share the same general formula

Question 20

Structural isomerism

Answer 20

Same molecular formula but different structural formula

Question 21

Stereoisomerism

Answer 21

Same structural formula but different spacial arrangement

Question 22

Nucleophile

Answer 22

Lone pair donor

Question 23

Electrophile

Answer 23

Lone pair acceptor

Question 24

Standard enthalpy of atomisation

Answer 24

Enthalpy change when one mole of gaseous atoms are formed under standard conditions

Question 25

First electron affinity

Answer 25

Enthalpy change when one mole of electrons are added to one mole of gaseous atoms

Question 26

Lattice enthalpy of formation

Answer 26

Enthalpy change when one mole of a solid ionic compound is formed from its gaseous ions

Question 27

Lattice enthalpy of dissociation

Answer 27

Enthalpy change when one mole of a solid ionic compound is dissociated into its gaseous ions

Question 28

Enthalpy of hydration

Answer 28

Enthalpy change when water molecules surround one mole of gaseous ions

Question 29

Enthalpy of solution

Answer 29

Enthalpy change when one mole of solute dissolves completely to form a solution where the ions are far enough apart that they don't interact

Question 30

Hydration

Answer 30

When ions are surrounded by water molecules

Question 31

Entropy

Answer 31

Measure of randomness of a reaction

Question 32

Order of reaction

Answer 32

The power of the concentration of the molecule in the rate equation

Question 33

Rate-determining step

Answer 33

Slowest step in a reaction

Question 34

Salt bridge

Answer 34

Filter paper soaked in a solution to allow ions to pass and complete the circuit

Question 35

Bronsted-Lowry acid

Answer 35

Proton donor

Question 36

Bronsted-Lowry base

Answer 36

Proton acceptor

Question 37

Weak acid

Answer 37

Acid that has a very low degree of dissociation.

Question 38

Equivalence point

Answer 38

The point in titration where enough acid or alkali has been added to neutralise the solution

Question 39

Buffer

Answer 39

A solution that can resist changes in pH

Question 40

Transition metal

Answer 40

Metals found in the d-block and with partially filled d-orbitals

Question 41

Ligand

Answer 41

Molecules that have a lone pair of electrons, available to form a dative bond with a metal ion

Question 42

Complex ion

Answer 42

An ion made with a metal ion datively bonded with one or more ligands

Question 43

Chiral centre

Answer 43

A carbon atom bonded to 4 different groups

Question 44

Pair of enantiomers

Answer 44

Two isomers showing optical isomerism

Question 45

Optical isomerism

Answer 45

Pairs of molecules which differ in the way they rotate polarised light; contains chiral carbons

Question 46

Racemic mixture

Answer 46

A mixture of a pair of enantiomers, causing no rotation on a plane of polarised light

Question 47

Fatty acids

Answer 47

Carboxylic acids found in oils and fats

Question 48

Acid derivatives

Answer 48

Compounds containing the acyl group in the structure

Question 49

Hydrolysis

Answer 49

Breakdown of a molecule using water

Question 50

Inductive effect

Answer 50

Unequal sharing of the bonding electron pair between atoms