Question

Show the formation of chloride ion.(Atomic number of chlorine = 17)

Answer 1

The number of valence electrons lost or gained by an atom to attain stability is called valency.

The atomic number of chlorine = 17

Electronic configuration = 2,8,7

since chlorine has seven electrons in its outermost shell, it does not have a stable electronic configuration.

chlorine gains one electron and achieves the stable configuration as 2,8,8

$$\begin{gathered} \mathrm{Cl}+1{\mathrm{e}}^{-}\to {\mathrm{Cl}}^{-} \\ 2,8,72,8,8 \end{gathered}$$

A chlorine atom($\mathrm{Cl}$) has 17 protons and 17 electrons. On gaining one electron, it becomes a chloride ion (${\mathrm{Cl}}^{-}$).