Question

what is ionation energy?How it is varin groups and periods​

Answer 1

As the atomic radius decreases, it becomes harder to remove an electron that is closer to a more positively charged nucleus. Conversely, as one progresses down a group on the periodic table, the ionization energy will likely decrease since the valence electrons are farther away from the nucleus and experience greater shielding. They experience a weaker attraction to the positive charge of the nucleus. Ionization energy increases from left to right in a period and decreases from top to bottom in a group.

Answer 2

ionization energy or ionisation energy is the minimum amount of energy required to remove the most loosely bound electron of an isolated neutral gaseous atom or molecule. ..

As you move down a group, first ionization energy decreases. WHY? Electrons are further from the nucleus and thus easier to remove the outermost one.

2) As you move across a period, first ionization energy increases...

NOTE ( IT'S IONISATION/IONIZATION NOT IONATION)