Definitions

Question 1

Isotopes

Answer 1

Atoms with the same number of protoms but a different number of neutrons

Question 2

Relative atomic mass, Ar

Answer 2

The weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom of Carbon 12

Question 3

Relative isotopic mass

Answer 3

Mass of an atom of an isotope compared to 1/12th of the mass an atom of Carbon 12

Question 4

Relative formula mass, Mr

Answer 4

Average mass of a molecule compared to 1/12th of the mass of an atom of carbon 12

Question 5

Enthalpy change of formation

Answer 5

Change in enthalpy when one mole of a substance in the standard state is formed from its pure elements u see the same conditions

Question 6

Enthalpy change of combustion

Answer 6

Enthalpy change which occurs when one mole of the compound is burned completely in oxygen under standard conditions and with everything in the standard state

Question 7

Enthalpy change of reaction

Answer 7

Enthalpy change when the reaction occurs in the molar quantities shown in the chemical equation, under standard conditions

Question 8

Enthalpy change of neutralisation

Answer 8

Enthalpy change when am acid and alkali react together under standard conditions to form 1 mole of water

Question 9

Catalyst

Answer 9

Increases the rate of reaction by providing an alternative reaction pathway with a lower activation energy, catalyst chemically unchanged at end of reaction

Question 10

Heterogeneous catalyst

Answer 10

Catalyst that is in a different phase from the reactants eg physical state
Reaction happens on surface

Question 11

Homogeneous catalyst

Answer 11

In the same physical state as the reactants

Form intermediate species by combining with catalyst which reacts to form products and reform catalyst

Question 12

Le chataliers principle

Answer 12

If there’s a change in concentration, pressure or temperature the equilibrium will move to help counteract the change

Question 13

Heterolytic fission

Answer 13

Bond breaks unevenly with one of the bonded pairs getting both electrons from the bonded pair

Question 14

Homolytic fission

Answer 14

Bond breaks evenly and each binding atom gets one electron from bonded pair
Radicals produced

Question 15

Stereoisomers

Answer 15

Have same structural formula but different arrangements in space
Occur when the two double bonded atoms each have two different atoms or groups attached to them

Question 16

Electrophillic addition

Answer 16

Alkene double bond opens up and the atoms are added to the carbon atom

Question 17

Electrophiles

Answer 17

Electron pair acceptors

Question 18

Markownikoffs rule

Answer 18

The major product from addition of hydrogen halide to an unsymmetrical alkene is the one where hydrogen adds to the carbon with the most hydrogen’s already attached

Question 19

Aldehyde

Answer 19

Have hydrogen and one alkyl group attached to the carbonyl carbon atom

Question 20

Ketone

Answer 20

Have two alkyl groups attached to carbonyl carbon atom