Question

why is Lithium atom smaller than potassium atom?​

Answer 1

Answer:

Potassium possesses more number of valence shells than lithium, so lithium is smaller than potassium atom. As it is clear, that chlorine is placed after sulphur so it has a smaller size and thus, its tendency to gain electron is- more than S.

Answer 2

Answer:

because Li is 2s1 and Na is 3s1