Question

What is the reason for positive charge on a sodium ion and a negative charge on a chloride ion in the formation of Sodium chloride?

Answer 1

1. Sodium loses an electron to chlorine. As a result, it has one more proton than the number of electrons and its net charge will be positive $\left(+1\right)$. Hence, it becomes a sodium ion $\left({\mathrm{Na}}^{+}\right)$.
2. Similarly, chlorine gains an electron which causes its net charge to become negative $\left(-1\right)$ due to the extra electron. Hence, it becomes a chloride ion $\left({\mathrm{Cl}}^{-}\right)$.