For main-group elements, are outer electron configurations

Solution 17P:

Here, we are going to explain the electron configurations of a group and a period of the periodic table.

Step 1:

For the main-group elements, the valence electrons are equal to those in the outermost principal energy level . Thus, the group number of a main-group element is equal to the number of valence

electrons for that element.

For example: Group 2A(2) elements have outer electronic configuration ns.2 where n is the no of period and 2 is the group number which is equal to the valence electrons.