Question

The atomic numbers of few elements are given below. Calculate the number of valence electrons in each case and find the value of X, Y and Z.

Elements	Atomic number	Number of valence electrons
Neon	10	X
Sodium	11	Y
Magnesium	12	Z

• A. X-4; Y-2; Z-8
• B. X-8; Y-2; Z-3
• C. X-8; Y-1; Z-2
• D. X-8; Y-2; Z-1

Answer 1

The correct option is C X-8; Y-1; Z-2

$\bullet$ The electronic configurations of the given elements are:$$\begin{array}{cc}\text{Element}& \text{Electronic configuration}\\ \text{Neon}& \text{2, 8}\\ \text{Sodium}& \text{2, 8, 1}\\ \text{Magnesium}& \text{2, 8, 2}\end{array}$$
$\bullet$ Valence electrons are the electrons present in the outermost (valence) shells of the atom.

$\bullet$ Thus, the number of valence electrons in:
Neon = 8
Sodium = 1
Magnesium = 2