Question

Why is the first ionisation energy of boron less than that of beryllium?

Answer 1

The most easily removed electron in Boron is that in the 2p orbital, higher in energy than the 2s electrons in Beryllium. It therefore needs less energy for total removal than does the 2s electron of Boron.

Answer 2

Answer:

The most easily removed electron in Boron is that in the 2p orbital, higher in energy than 2s electrons in Beryllium. It therefore needs less energy for total removal than does the 2s electron of Boron.