Topic 1

Question 0

Ionization energy, first

Answer 0

Energy required to remove one e– from an atom in its gaseous state. Increases across a period (due to increasing nuclear attraction), except for slight drops (due to the commencement of pairing of e- into orbitals  greater electron repulsion). Decreases down a group (due to increased number of energy levels  increased electron shielding).

Question 1

Avogadro’s constant:

Answer 1

6.022 x 10^23

Question 2

Isotope:

Answer 2

An atom that contains the same number of protons but a different number of neutrons

Question 3

Mass number:

Answer 3

Total number of nucleons

Question 4

Atomic radius:

Answer 4

Half the distance between the nuclei of two bonded atoms of the same element. Decreases across period as nuclear charge increases. Increases down a group because of greater number of energy leve

Question 5

Anion: A –

Answer 5

charged ion. Decrease in size across a period as they are isoelectronic but have an increased nuclear charge. Contain more e- than their parent atom, so they are larger in size.

Question 6

Cation:a*

Answer 6

Cation: A + charged ion. Decrease in size across a period. Contain less e- than their

Question 7

Electronegativity:

Answer 7

Relative measure of the attraction that an atom has for a shared pair of e- when it is covalently bonded to another atom. Inversely proportional to size of atom  F is most electronegative

Question 8

Ligand:

Answer 8

Ligand: A species which contains a non-bonding pair of electrons, able to form coordinate/dative covalent bonds

Question 9

Period:

Answer 9

Period: Elements with the same outer shell of valence e-.

Question 10

Structure, molecular covalent:

Answer 10

Structure, molecular covalent: Usually soft and malleable unless hydrogen bonded. Low m.p. and b.p. Do not conduct in any state. Often soluble in non-aqueous solvents, unless they can hydrogen bond to water.

Question 11

Structure, giant ionic:

Answer 11

Structure, giant ionic: Hard but brittle. High m.p. and b.p. Conduct when molten or aqueous, but not as solids.

Question 12

Structure, giant covalent:

Answer 12

Structure, giant covalent: Very hard but brittle. Very high m.p. and b.p. Do not conduct in any state. Insoluble.

Question 13

Bond enthalpy:

Answer 13

Bond enthalpy: The average enthalpy change of breaking a bond between gaseous atoms into its constituent gaseous atoms.

Question 14

Endothermic

Answer 14

A reaction in which energy is absorbed. ΔH is +. Reactants more stable than products.

Question 15

Exothermic:

Answer 15

Exothermic: A reaction in which energy is evolved. ΔH is –. Products more stable than reactants.

Question 16

Standard bond enthalpy:

Answer 16

Standard bond enthalpy: The average energy change when one mole of a specific type of bond is broken or created under standard conditions.

Question 17

Standard enthalpy change of formation

Answer 17

The energy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

Question 18

Enthalpy change of combustion

Answer 18

Enthalpy of Combustion: The energy released when one mole of a compound is burned at std.

Question 19

Electron affinity:

Answer 19

Electron affinity: Enthalpy change when an e- is added to an isolated atom in the gaseous state.

Question 20

Enthalpy

Answer 20

The internal energy stored in the reactants. Only changes in enthalpy can be measured.

Question 21

Half-life:

Answer 21

Half-life: The time taken for the concentration of the reactant to fall to half of its initial value.

Question 22

Standard electrode potential:

Answer 22

However, the electrode potential of one half cell can be compared against another half-cell, by convention, the hydrogen half-cell, which is arbitrarily given a value of 0 V.