Question

How is an anion formed?

Answer 1

• An ion is formed when an atom losses or gains electrons.
• Ions are of two types - cation (positive ion) and anion (Negative ion).
• While the negatively charged ion or the ion formed by accepting the electrons is known as an anion. For example - ${\mathrm{Cl}}^{-}$ion is formed when a Chlorine atom accepts one electron, ${\mathrm{O}}^{-2}$ accepts two electrons, etc.
• Those elements which need one or more electrons to acquire a stable noble gas configuration, generally form an anion.
• For example - Chlorine has the atomic number of 17 and its electronic configuration is $2,8,7$. Therefore, it needs only electrons to become stable.
• $\mathrm{Cl}+{\mathrm{e}}^{-}\to {\mathrm{Cl}}^{-}$

Therefore, anions are formed when an atom accepts at least one electron.