How does the electronic configuration of an atom of an element relate to its position in the modern periodic table? Explain with one example.
The position of element depends upon number of valence electrons which depend upon electronic configuration. Those elements which have same valence electrons, occupy same group.
Those elements which have one valence electron belong to group 1.
Elements with two valence electrons belong to group 2.
Period number is equal to number of shells.
If valence electrons are equal to 1, it belongs to group 1. If it has 2 shells, it belongs to second period, e.g. if element ‘X’ has atomic number 11, its electronic configuration is 2, 8, 1. It has one valence electron, it belongs to group 1 and it has three shells therefore, it is in third period.