Explain why size of anion is larger than parent atom.

Explanation

Anion is formed by the gass of one or more electrons by the gaseous atom. In the anion , the nuclear change is the same as that in the parent atom but the number of electrons has increased .Since same nuclear change now acts on increased number of electrons, the effective nuclear change per election decrease in the anion. The electron cloud is held less tightly by the nucleus. Thus causes increase in the size ,
Ex : The relative size of chlorine atom and chloride ion ia as follows.
`{:(17,"electrons",18),(+17,"Nuclear charge",+17),(99"pm","size",181"pm"):}`