i) Who proposed Modern - periodic law?
ii) How does the electronic configuration of an atom of an element relate to its position in the modern periodic table? Explain with one example.

Explanation

i) Henry Mosely proposed modern periodic law.
ii) The position of elements depends upon number of valence electrons which depend up on electronic configuration. Those elements which have some valence electrons, occupy same group. Those elements which have one valence electron belong to group 1. Elements which have two valence electrons belong to group 2. Period number is equal to the number of shells. Example, atomic number of Na is 11, So its electronic configuration is 2, 8, 1. As sodium has one valence electron in its valence shell, so it belongs to group 1. As sodium has 3 shells, it belongs to 3rd period.