Question

Position of the elements in the periodic elements......

How is the problem regarding the position of cobalt (⁵⁹Co) and nickel (⁵⁹Ni) in Mendeleev’s periodic table resolved in modern periodic table?

Answer 1

Mendeleev ranked the elements according to their increasing atomic masses. However, certain elements have higher atomic masses than others. For example, cobalt (Co), which has an atomic mass of 58.93, is positioned above nickel (Ni), which has an atomic mass of 58.71. The atomic number of each element served as the basis for the creation of the modern periodic table. Co and Ni have atomic numbers of 27 and 28, respectively. Thus, nickel comes after cobalt.