Ionisation across period

Question 1

The ionisation energy across a period generally increases due to the following factors:

Answer 1

Across a period the nuclear charge increases

The shielding by inner shell electrons remain reasonably constant as electrons are being added to the same shell

Question 2

What is the nuclear charge increasing and why does it increase ionisation energy

Answer 2

Increasing proton number gives nucleus stronger positive charge

This causes the atomic radius of the atoms to decrease, as the outer shell is pulled closer to the nucleus, so the distance between the nucleus and the outer electrons decreases

Question 3

Why does The shielding by inner shell electrons remain reasonably constant as electrons are being added to the same shell

Answer 3

It becomes harder to remove an electron as you move across a period; more energy is needed

as there are not more shells to block nuclear charge from valence electron

Question 4

There is a large ……. in ionisation energy between the last element in one period, and the first element in the next period

Answer 4

decrease

Question 5

Why is there a large decrease in ionisation energy between the last element in one period and the first in the next

Answer 5

This is because:

There is increased distance between the nucleus and the outer electrons as you have added a new shell

There is increased shielding by inner electrons because of the added shell

These two factors outweigh the increased nuclear charge