Question

Why is negative ion is always larger than that of the corresponding atom?

Answer 1

in a negative ion the no of electrons increases while nuclear charge remain same as that of corresponding atom due to which the size of negative ion increases due to more electrons and same nuclear charge. moreover in negative ion the electron electron repulsion also increases due to added electrons so size inceases.

Answer 2

negative ion is formed when parent atom gain electrons as no. of electrons increases hence inter electronic repulsion increases therefore size of negatively charged ion increases