Question

Atomic numbers (Z) of some elements are given here. Write down the number of electron present in the outermost shell of each of them.
Element H C Na Cl N
Z 1 6 11 17 7
Number of electrons in the outermost shell

Answer 1

H=1, C=4, Na=7, N=5, in general the number of electrons in the outermost shell of a particular atom.

Similarly, chlorine has only seven electrons in its outermost shell, while sodium has just one.

Even the group 1 elements have just one valence electron as well as group 18 elements.