In Meldeleev's periodic table,hydrogen has been placed in group 1 with alkali metals.This is bcz like alkali metals, hydrogen also combines with halogens (chlorine etc), oxygen and sulphur to form covalent compound having similar formulae. This means that hydrogen resembles alkali metal in some of the properties.Hydrogen also resembles halogens in some of the properties. For ex, like halogens (F2, Cl2,and Br2 ), hydrogen also exists in the form of diatomic molecules (H2).Moreover, hydrogen also combines with certain metals to form ionic compounds.All these properties show that hydrogen could also be placed in group 7 of halogen elements. On the basis of properties, hydrogen element could be placed in alkali metal group as well as in halogen group. Thus, Meldeleev's periodic law could not assign correct position of hydrogen in the periodic table....