Explain why hydrogen is not placed with the halogen in the periodic table.

Explanation

(i) Hydrogen has a tendency to gain one electron to form hydride ion `(H^-)` whose electronic configuration is similar to the noble gas (He).
(ii) However the electron affinity of hydrogen is much less than that of halogen atoms
(iii) Hence hydrogen is less reactive as compared to halogens.
(iv) `:.` Due to this unique behaviour hydrogen is not placed with halogens in the periodic table.