AS 2 - Definitions

Question 1

Structural Formula

Answer 1

shows the minimal detail for the arrangement of atoms in a molecule

Question 2

Displayed Formula

Answer 2

shows the relative positioning of all the atoms in a molecule and the bonds between them

Question 3

General Formula

Answer 3

shows the simplest algebraic formula of a member of a homologous series

Question 4

Skeletal Formula

Answer 4

shows simplified organic formula by removing hydrogen atoms from alkyl chains, leaving just the carbon chain and functional groups

Question 5

Homologous Series

Answer 5

series of organic compounds which have the same functional group, general formula and similar chemical properties, but with each successive member differing by a CH2 unit

Question 6

Stereoisomers

Answer 6

compounds with the same molecular and structural formula, but have their atoms arranged differently in space

Question 7

(Structural) Isomers

Answer 7

compounds with the same molecular formula, but have a different structural formula (atoms arranged differently)

Question 8

Curly Arrows

Answer 8

represent the movement of an electron pair

Question 9

Homolytic Fission

Answer 9

the breaking of a covalent bond, where one of the bonded electrons goes to each atom, forming two free radicals

Question 10

Heterolytic Fission

Answer 10

the breaking of a covalent bond, with both of the bonded electrons going to one of the atoms, forming negative and positive ions

Question 11

Hydrocarbon

Answer 11

compound containing carbon and hydrogen only

Question 12

Fractional Distillation

Answer 12

separation of a mixture according to differences in boiling points

Question 13

Biofuel

Answer 13

a fuel that can be obtained from plants or animals

Question 14

Pi Bond

Answer 14

bond formed from the sideways overlap of adjacent p orbitals

Question 15

Sigma Bond

Answer 15

single covalent bond made up of two shared electrons

Question 16

Biodegradable (non)

Answer 16

material (that cannot be) broken down naturally by bacteria in the environment

Question 17

Reflux

Answer 17

continuous evaporation and condensation, without loss of vapours

Question 18

Standard Enthalpy of Formation

Answer 18

enthalpy change when one mole of a compound is formed from its elements, in their standard state, under standard conditions

Question 19

Standard Enthalpy of Reaction

Answer 19

enthalpy change when the number of moles of reactants, as shown in the equation, react together under standard conditions

Question 20

Standard Enthalpy of Combustion

Answer 20

enthalpy change when one mole of an element/compound reacts completely with oxygen, under standard conditions

Question 21

Average Bond Enthalpy

Answer 21

average enthalpy change on breaking one mole of a covalent bond in a gaseous molecule, under standard conditions

Question 22

Hess’s Law

Answer 22

the total enthalpy change for a chemical reaction is independent of the route by which the change takes place, provided the initial and final conditions are the same

Question 23

Rate

Answer 23

the change in concentration of a reactant or product in a given time

Question 24

Activation Energy

Answer 24

the minimum energy needed for a reaction to occur

Question 25

Catalyst

Answer 25

a substance that increases the rate of reaction without being used up. It provides an alternative route, with a lower activation energy

Question 26

Dynamic Equilibrium

Answer 26

A system where forward and reverse reactions proceed at identical rates

Question 27

Le Chateliers Principle

Answer 27

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

Question 28

Greenhouse effect

Answer 28

process by which the absorption and subsequent emission of infrared radiation by atmospheric gases warms the lower atmosphere and the planet’s surface

Question 29

Ozone Depletion Potential

Answer 29

relative amount of breakdown of the ozone layer caused by a particular substance