why ionisation energy decrease on moving down the group - Chemistry - The s-Block Elements

Question

why ionisation energy decrease on moving down the group

Akanksha · Accepted Answer

The amount of energy required to remove the outermost electron from
an isolated, neutral gaseous atom to form a cation is known as
ionisation energy

Ionisation energy decreases as we proceed down the group This is
because the size of the atom increases as we move down the group,
and therefore the attraction between the nucleus and the outermost
electron decreases Because of this, it becomes easier for atom to
lose the valence electrons For example, the ionisation energy of
potassium is more than that of sodium

Ionisation energy increases as we move from left to right across a
period Thus the ionisation energy of carbon is more than that of
lithium