The property of hydrogen which distinguishes it from other alkali metals is

Like alkali metals⇒ It [hydrogen] form unipositive ion H+ [ It indicates the electropositive character} Examples : (1) HCl → H+ + Cl- (2) NaCl → Na+ + Cl⇒ It also has high affinity for non--metals.    examples : HCl- , NH3 , H2O etc⇒ It also acts as reducing aqent    examples : CuO + H2 → Cu + H2OBut hydrogen shows non metallic character, where as Alkali metals are purley  metals.