What has a higher ionization energy? Ca or Ba and Ca or Br Explain. (using CER)

Answer 1

What the heck is CER?

Ionization energy increases going from left to right across a period, and from bottom to top within a group.

This is because within a period, as you go left to right, the number of shells stays the same, but there are more protons attracting the electrons, so the radius is smaller and it is harder to remove an outer electron. In a group, as you go up, there are fewer shells, the radius is smaller, and it is harder to remove the electron.

Comparing Ca and Ba, Ca would have a greater IE. Comparing Ca and Br, Br would have a greater IE.