Question

The net charge on a sulfide ion ($S^{2-}$) is 2-. How does this ion obtain its charge?

Answer 1

Hint: An ion is formed when there is a change in the number of electrons in the atom. When the positive charge is there on the element then there is the removal of an electron and when the negative charge is there on the element then there is the addition of an electron.

Complete answer:
An atom contains electrons, protons, and neutrons and the components are different in different atoms. An ion is formed when there is a change in the number of electrons in the atom. When the compounds are formed, the electrons are participating in the bond formation. When one positive charge is there on the element then there is the removal of one electron, when two positive charges are there on the element then there is the removal of two electrons and so on. When one negative charge is there on the element then there is the addition of one electron, when two negative charges are there on the element then there is the addition of two electrons and so on. This removal or addition of electrons takes place to obtain the nearest noble gas configuration by completing its octet.
Sulfur is the element of group 16 and having atomic number 16 so, its electronic configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^4$. Therefore, it needs two electrons to complete its octet and obtain the noble gas configuration of argon. Hence it adds two electrons to its atom to form the sulfide ion and it obtains -2 charge so, it is written as ($S^{2-}$).

Note:
Some of the ions are $N{a}^{+}$ because one electrons is removed, $M{g}^{2+}$ because two electrons are removed, $A{l}^{3+}$ because three electrons are removed, $F^{-}$ because one electron is added, $N^{3-}$ because three electrons are added.