Question

How does the following property vary on moving down group 17?

Ionisation energy

Answer 1

1. Ionisation energy decreases as we move down Group 17.
2. This is because the atomic size increases with each successive element down the group.
3. Larger atoms have their outer electrons farther from the nucleus, experiencing less attraction.
4. This reduced attraction makes it easier to remove an electron, lowering the ionisation energy.
5. Fluorine has the highest ionisation energy, and iodine the lowest in the group.