Give the general group characteristics applied to hydrogen with respect to similarity in properties of hydrogen with –

(a) alkali metals of group 1 [IA]
(b) halogens of group 17 [VIIA].

with special reference to valency electrons & ion formation.

Similarity in properties of hydrogen with

(a) Alkali metals of group 1 [IA] :

1. Electronic Configuration — Valency electron - one valence electron e.g., H = 1; Li = 2, 1; Na = 2, 8, 1; K = 2, 8, 8, 1
2. Ion Formation — Electropositive character exhibited.
   H – 1e^– ⟶ H¹⁺
   Li – 1e^– ⟶ Li¹⁺
   Na – 1e^– ⟶ Na¹⁺
3. Valency — Electrovalency of 'one' exhibited. H¹⁺, Li¹⁺, Na¹⁺

(b) Halogens of group 17 [VIIA] :

1. Electronic Configuration — One electron less than the noble gas e.g., H = 1 [He = 2]; F = 2,7; [Ne = 2,8]; Cl = 2,8,7 [Ar = 2,8,8]
2. Ion Formation — Electronegative character exhibited.
   H + 1e^– ⟶ H^1-
   F + 1e^– ⟶ F^1-
   Cl + 1e^– ⟶ Cl^1-
3. Valency — Electrovalency and covalency exhibited
   Hydrogen - forms NaH [electrovalent]; CH₄ [covalent]
   Chlorine - forms NaCl [electrovalent]; CCl₄ [covalent]