Trends of the periodic table

Ionization Energy

What is ionization energy?

ionization energy is the amount of energy required to remove the outmost electron.

Ionization Trends:

The period trend

ionization energy increases as you go from left to right across a period because elements on the right of a chart want to take others atom's electrons, because they are too close to achieving the octet. Elements on the left of the chart would prefer to give up their electrons so it is easy to remove them, requiring less energy.

The group trend

Ionization energy decreases as you go down a group, because the shielding effect makes it easier to remove the outer most electrons from those atoms that have many electrons.