HELP Do elements with higher energy levels have a lower ionisation energy?

Sansy786

Hi I am struggling to understand ionization energy.

(edited 7 months ago)

Reply 1

BankaiGintoki

Original post by Sansy786

Hi I am struggling to understand ionization energy.

Down a group
Higher atomic radius, higher electron shielding, reduce electrostatic attraction to outer electron, reduced first ionisation energy. (The increasing nuclear charge is outweighed by atomic radius and electron shielding)
Across a period
Smaller atomic radius, same electron shielding, greater nuclear charge, greater electrostatic attraction to outer electron, higher first ionisation energy.
This is the general trend - there are 2 small dips in period 2 and 3
1st is going from 2s2 or 3s2 orbital to 2p1 or 3p1. P orbital higher energy level, less energy is needed to remove
2nd is going from 2p3 or 3p3 orbital to 2p4 or 3p4. Paired electron is orbital repel, easier to remove.

Successive ionisation energy. Always increases, as the electrostatic attraction is greater on the remaining electrons. If you remove an electron from an inner shell, whilst the previous is on the outer shell, there would be a big ‘jump’ in energy required - so you can use the data to find how many outer electrons an element has,

Helium has the highest first ionisation energy- as it is the 1st period, and it is at the end of that period.
When you talk about ionisation energy being ‘less’ or ‘greater’, you talk about it with respect to going down/up a group, or across a period.