Periodicity

Question 1

What is periodicity?

Answer 1

The repeating trend in properties of the elements.

Question 2

Define first ionisation energy.

Answer 2

First ionisation energy is 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 3

Name the three factors which affect ionisation energy.

Answer 3

Atomic Radius: the greater the distance between the nucleus and outer electron the less the nuclear attraction.

Nuclear Charge: more protons, increased nuclear charge, greater attraction.

Electron shielding: inner shell electrons repel outer shell electrons, reduces attraction.

Question 4

Explain and describe the trend in ionisation energy down a group.

Answer 4

Atomic radius increases,
More inner shells, more shielding,
Nuclear attraction to outer electron decreases,
1st ionisation energy decreases.

Question 5

Explain and describe the trend in 1st ionisation energy across a period.

Answer 5

Nuclear charge increases (more protons),
Same shell so similar shielding,
Nuclear attraction increases,
Atomic radius decreases,
Ionisation energy increases.