Question

Given below are the atomic number of elements. What will be the no. of valence electrons in each of them respectively?
$$\begin{array}{cc}\text{Element}& \text{Atomic no.}\\ \text{Carbon}& \text{6}\\ \text{Nitrogen}& \text{7}\\ \text{Oxygen}& \text{8}\end{array}$$

• A. 4, 2, 3
• B. 4, 5, 6
• C. 4, 3, 2
• D. 6, 7, 8

Answer 1

The correct option is B 4, 5, 6

$\bullet$ The maximum number of electrons that can be accommodated in a shell is given by $2n^2$. Hence, K, L, M shell can accommodate a maximum of 2, 8, 18 electrons respectively.

$\bullet$ The electronic configuration of the given elements is:$$\begin{array}{cc}\text{Element}& \text{Electronic configuration}\\ \text{Carbon}& \text{2, 4}\\ \text{Nitrogen}& \text{2,5}\\ \text{Oxygen}& \text{2, 6}\end{array}$$
$\bullet$ Valence electrons are the electrons present in the outermost (valence) shell of an atom.

$\bullet$ Thus, the number of valence electrons in each of these atoms are 4, 5 and 6 respectively.