Chem- AS Inorganic & Physical definitions

Question 1

First ionisation energy

Answer 1

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

Question 2

Second ionisation energy

Answer 2

The energy required to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions

Question 3

Successive ionisation energy

Answer 3

A measure of the energy required to remove each electron in turn

Question 4

Oxidation number

Answer 4

A measure of the number of electrons that an atom uses to bond with atoms of a different element

Question 5

Oxidation

Answer 5

The loss of electrons/ an increase in oxidation number (state)

Question 6

Oxidising agent

Answer 6

A reagent which oxidises another species, it accepts electrons from the other species and is itself reduced

Question 7

Reduction

Answer 7

The gain of electrons/ a decrease in oxidation number (state)

Question 8

Reducing agent

Answer 8

A reagent which reduces another species, it donates electrons to the other species and is itself oxidised

Question 9

Redox

Answer 9

A reaction where both oxidation and reduction take place

Question 10

Disproportionation

Answer 10

A reaction in which one element is simultaneously oxidised and reduced

Question 11

Displacement reaction

Answer 11

A redox reaction between a halogen and the halide ion of a less reactive halogen in which the halide ion is oxidised by the more reactive halogen

Question 12

Exothermic

Answer 12

Heat is given out to the surroundings (the reactants lose energy)

Question 13

Endothermic

Answer 13

Heat is taken in from the surroundings (the reactants gain energy)

Question 14

Activation energy

Answer 14

The minimum energy required to start a reaction by the breaking of bonds

Question 15

Standard conditions

Answer 15

A pressure of 100kPa (1 atmosphere), a stated temperature (usually 298K/25 C), and a concentration of 1.0 moldm^-3 (for reactions with aqueous solutions)

Question 16

(Standard) enthalpy change of reaction

Answer 16

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation (under standard conditions, all reactants and products being in their standard states)

Question 17

(Standard) enthalpy change of formation

Answer 17

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements (in their standard states under standard conditions)

Question 18

(Standard) enthalpy change of combustion

Answer 18

The enthalpy change that takes place when one mole of a substance reacts completely with oxygen (in their standard states under standard conditions)

Question 19

Average bond enthalpy

Answer 19

The average enthalpy change that takes place when breaking, by homolytic fission, 1 mole of a given type of bond in the molecules of a gaseous species

Question 20

Enthalpy change of neutralisation

Answer 20

The energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O(l) under standard conditions

Question 21

Catalyst

Answer 21

Speeds up a reaction without being consumed by the overall reaction

Question 22

Dynamic equilibrium

Answer 22

The equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reversed reaction

Question 23

Le Chatelier’s Principle

Answer 23

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