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 electronic configuration of an atom of an element helps in finding the position of the element in the modern periodic table as follows:

1. The number of electron shells of an element is equal to the period number of the element.

2. The number of valence electrons present in the electronic shell (upto 2 valence electrons) gives the group number of an element while more than 2 valence electrons, the group number is equal to the number of valence electrons plus 10.

For example: The atomic number of element = 17

Electronic configuration of element = 2,8,7

The electronic configuration of an atom of an element gives its position in the modern periodic table.

(i) The ‘period number’ of an element is equal to the number of electron shells in its atom.

(ii) - The group number of an element having upto two valence electrons is equal to the number of valence electron.

-The group number of an elements having more than 2 valence electrons is equal to the number of valence electrons plus 10.

Example: If the electronic configuration of an element is 2, 8, 7

The period number = no. of electron shells in its atom

Period number = 3

Since, the electron is going to have more than 2 outermost electrons, so Group number = no. of outermost electrons + 10

Group number = 7+10

Group number =17