Ionization Energy

                  Ionization energy or ionization potential is the energy required to completely remove an electron from gases atom or ion. The closer and more tightly bound an electron is to the nucleus, the more difficult will be to remove. the higher its ionization energy will be.

• The first ionization energy is the energy required to remove one electron from the parent atom.
• Second ionization energy is the energy required to remove second valence electron from the divalent ion and so on.Successive ionization energy increases.

                      Second ionization energy is always greater than the first ionization energy. Ionization energy increases moving left to right across a periods. ( decreases atomic radii ). Ionization energy decreases moving down the group ( increases atomic radii ).

                       Group one elements have low ionization energy because the loss of an electron from a stable octet.