Question

Which element from Group 2 has the greatest ionization energy?
a. Beryllium
b. Calcium
c. Barium
d. Radium
*And the most important part: why?* Which element from Group 2 has the greatest ionization energy?
a. Beryllium
b. Calcium
c. Barium
d. Radium
*And the most important part: why?* @Chemistry

Answer 1

A. Beryllium
This is because the outer electron is very close to the nucleus, the force of attraction is high and so more energy is needed to remove that outer electron.
As we go down the group, the radius of the atom increases, so the distance between the nucleus and the outer electron increases,
therefore the force of attraction between the nucleus and outer electron is reduced;
so less energy is needed to remove the outer electron. Hence, the ionization energy reduces as we go down Group 2.

Answer 2

Aha. Thanks!