POSITION OF HYDROGEN IN THE PERIODIC TABLE (HYDROGEN AND HALOGENS)

HYDROGEN AND HALOGENS  

Similarities

1.      Hydrogen is a gas  like most of halogens.

2.      Hydrogen exists in diatomic form (H₂ )  like F₂ , Cl₂ and I₂ 

3.      Hydrogen requires one electron to  complete its outermost shell just like halogens

4.      Both hydrogen and halogens form stable ionic compounds with alkali metals.

5.      Hydrogen forms H ^– ion by gaining one electron like F ^– , Cl ^– , Br ^–  etc.

Differences

1. Hydride ion H ^– is unstable in aqueous solution while halide ions, i.e F ^–, Cl^–Br ^– etc.

are stable.

                                                                H ^– + H₂O           H₂ + OH ^–

2.      Hydrogen has just one electron in its outermost shell while halogens have seven electrons in their outermost shells.

3.      Hydrogen forms very stable compound H₂O with oxygen while halogens do not form.

4.      Alkali metal hydrides  e.g; NaH are strongely basic while alkali metals halides e.g; NaCl are neutral.

5.      Hydorgen can form H⁺ ion by loosing electron, while halogens do not form positive ions.