Atomic Structure: Ionisation Energy

Definition of ionisation energy
1. The minimum amount of energy needed to remove 1g of electron from 1 mol of gaseous atom to form 1 mol of gaseous ion
Trend of ionisation energy
1. down the group
  1. I.E. decreases
    1. Shielding effect
    2. nuclear attraction decreases
    3. size of atom increases
2. across the group
  1. I.E. increases
    1. # of protons increases
    2. nuclear attraction increases
    3. nuclear charge increases
    4. electron energy level will be held tightly together
I.E. between shells
1. as the electrons get closer to the nucleus, I.E. increases
  1. log of ionisaion energy:
Factors affecting I.E.
1. atomic radius
  1. Smaller the atomic radius, the higher is the atomic energy
2. Nuclear charge
  1. the higher the positive charge of the nuceus, stronger is it's attraction for the electrons
3. Orbital penetration
  1. It's easier to remove electrons from p orbitals than from s orbitals, because the s orbitals penetrate towards the nucleus more closely than the p orbitals
4. Electron pairing
  1. paired electrons are easier to remove than unpaired ones because repulsion between electrons in the same orbital is higher than repulsion between electrons in different orbitals
5. Shielding or screening effect of the inner orbitals
  1. inner electron orbitals effectively shield the outermost electrons from the nucleus

Resource summary

	Created by Alex Manktelow about 10 years ago