What happens to electron affinity as you move down a group?
Electron Affinity decreases as you move down a group.
- a measure of the attraction between the incoming electron and the nucleus
- the stronger the attraction, the more energy is released
It decreases down a group because of increased shielding and decreasing effective nuclear charge.
Shielding refers to the number of electrons that are 'blocking' the incoming electron from 'feeling' the positive charge of the nucleus.
So as you move down a group, more electrons are shielding the incoming electron from the positively charged nucleus, making the electron affinity decrease.