Periodicity

Question 1

What is the general trend down a group

Answer 1

Ionisation energy decreases down the group because increased nuclear charge is outweighed by increased atomic radius and increased shielding

Attraction weaker between nucleus and outermost electrons

Question 2

What is the trend across a period

Answer 2

Ionisation energy increases across period because increased nuclear charge
Constant shielding leading to a decrease in atomic radius stronger attraction between nicleus and outer electron

Question 3

What about the dips in group 3

Answer 3

The electrons are in a higher sublease so need less energy to remove