Question

The radius of na+ cation is less than that of na atom. Give reason

Answer 1

radius of Na+ is less than Na because in Na+ 11 electrons are present and in Na+ only 10 electrons are present so effective nuclear charge of Na+>Na so size of Na+<Na.

Answer 2

Answer:

ATOMIC SIZE: Distance from the nuclius to the outermost electron.

Na⁺→Loss of one electron.

The atomic radius of Na⁺ is less than that of Na,because due to the loss of 1e ⁻,the inter electronic repulsion by the electrons in the inner shell decreases.

As the interelectronic repulsion decreases, the attraction between the nuclei  and the outermost electron increases,leading to the decrease in the atomic size.

NOTE:

1.Size of cation is always smaller than the parent atom.

2.Size of anioin is larger than the parent atom.