Question

Which two categories metal used to classify the elements in his periodic table?

Answer 1

A) Mendeleev used increase in atomic mass and formulae of hydrides and oxides as the 2 main criteria. b) Properties of elements are a periodic function of their atomic masses. c) Hydrogen exists as diatomic molecules, similar to those of Group 17. However, it also has 1 valence electron, like Group 1 elements