How does a negative ion differ from an uncharged atom of the same element?

When an atom or molecule accepts or looses an electron or electrons it gets either negative charge (when electrons gained) or a positive charge (when looses electron). The negative ion is called Anion and positve ion is called the Cation. An Ion can be Atomic or Polyatomic.

Example:

Sodium when looses one electron forms a cation i. e. Na⁺

Chlorine when gains one electron forms an Anion i. e. Cl⁻

Result:

A negative ion (Anion) differ from an uncharged atom of the same element in the number of electrons. An anion contains more electrons than its corresponding Neutral Element.