Question

In Mendeleev’s Periodic Table the elements were arranged in the increasing order of their atomic masses. However, cobalt with atomic mass of 58.93 amu was placed before nickel having an atomic mass of 58.71 amu. Give reason for the same.

Answer 1

Cobalt was placed in the group of rhodium (Rh) and iridium (Ir) because it has similar properties to them. Similarly, nickel was placed in the group of palladium (Pd) and platinum (Pt) because it has similar properties to them. In this case, he adjusted the position of the elements to place them with similar elements.