Why does the first ionization energy of elements increase down a group and across a row?

Question

I understand that this occurs but not why (particularly why it increases down a group).

Answer 1

Wrong: The first ionization energy of the elements decreases down a group because their atomic radius increases, so the force acted from nucleus to the electron of the outer shell decreases.

The first ionization energy increases across the same period - row - from left to right because the atomic radius is decreased. That's because we have more protons in the nucleus, stronger force on the electrons of the same outer shell, consequently higher ionization energy.

Answer 2

There is increasing atomic number and atomic mass. Hence on a charge basis and a mass basis you would have an increasing first ionization energy.

Answer 3

i think your question is wrong......the first ionisation energy actually decreases down the group and increses along the period .........this is because the atomic size increases down the group due to the addition of an extra shell and the same atomic size decreases across the row due to the addition of extra electron in the same shell