3&13. Periodicity

Question 1

Atomic radius

Answer 1

Radius of atom

Question 2

Ionic radius

Answer 2

Half the distance between two ions in a lattice that are barely touching.

Question 3

Electronegativity

Answer 3

The ability of an atom to attract the shared electrons in a covalent bond.

Question 4

Ionisation energy

Answer 4

The minimum energy required to remove the outermost electron in the gaseous state

Question 5

Melting and boiling points

Answer 5

The temperatures at which a substance changes state.

Question 6

Electron affinity

Answer 6

Minimum energy change when adding an electron to a gaseous atom.

Question 7

Trend in atomic radius across a period

Answer 7

Decreases

Increase in nuclear charge

Question 8

Trend in atomic radius down a group

Answer 8

Increases

More energy levels

Question 9

Trend in ionic radius across a period

Answer 9

Decreases until negative ions when it reaches maximum before falling.
Positive ions will get smaller than parent atom because there is a greater effective electric charge.
Negative ions will be larger as there is greater electron-electron repulsion and shielding.

Question 10

Trend in ionic radius down a group

Answer 10

Increases

More energy levels

Question 11

Trend in electronegativity across a period

Answer 11

Increases

Increased nuclear charge - greater force between nucleus and shared electrons

Question 12

Trend in electronegativity down a group

Answer 12

Decreases

Bond electrons further from nucleus

Question 13

Trend in ionisation energy across a period

Answer 13

Increases (generally)

Greater nuclear charge

Question 14

Trend in ionisation energy down a group

Answer 14

Decreases

More shielding and e-e repulsion

Question 15

Trend in melting and boiling points across a period

Answer 15

Rise across a period and reach maximum at group 4 then fall to min at group 0
Metals - larger positive charge and more delocalised electrons

Non-metals – in diatomic molecules v low but v high in giant covalent structures.

Question 16

Trend in melting and boiling points down a group

Answer 16

Group 1/2 – decreases
Non-metals - increase
More shielding – less attraction between nuclei and delocalised electrons
Larger atoms – greater intermolecular forces

Question 17

Trend in electron affinity across a period

Answer 17

Increases

Increased nuclear charge

Question 18

Trend in electron affinity down a group

Answer 18

Decreases

More shielding

Question 19

Transition metals must

Answer 19

o have variable oxidation states
o form complex ions with ligands
o have coloured compounds
o display catalytic and magnetic properties

Question 20

Complex ion

Answer 20

a species formed when when ligands bond to a central metal ion using coordinate bonds.

Question 21

Ligand

Answer 21

species with lone pairs of electrons that act as Lewis bases; they donate a pair of electrons to the central metal ion.

Question 22

 Monodentate ligand =

Answer 22

a ligand that forms only one coordinate bond with the ion.

Question 23

 Bidentate ligands =

Answer 23

a ligand that forms two coordinate bonds with the ion.

Question 24

 Polydentate ligand ).

Answer 24

a ligand that forms multiple coordinate bonds with the ion (e.g EDTA which forms 6

Question 25

 Homogenous catalyst =

Answer 25

a catalyst that is in the same physical state as the reactants.

Question 26

 Paramagnetism =

Answer 26

a form of magnetism whereby certain materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field.