Limitations of Mendeleev’s periodic table: Elements with large difference in properties were included in the same group. Eg: Hard metals like copper (Cu) and silver (Ag) were included along with soft metals like sodium (Na) and potassium (K). No proper position could be given to the element hydrogen. Non-metallic hydrogen was placed along with metals like lithium (Li), sodium (Na) and potassium (K). The increasing order of atomic mass was not strictly followed throughout. Eg. Co & Ni, Te &I. No place for isotopes in the periodic table.
