Which one of the following is the correct order of the valencies of elements Ne, Si, N and Mg ?

The valency of an element is determined by its combining capacity, which depends on the number of valence electrons in its outermost shell [1]. Neon (Ne) is a noble gas with a completely filled valence shell (2, 8), resulting in a valency of 0 [1]. Magnesium (Mg) has an electronic configuration of 2, 8, 2; it loses two electrons to achieve stability, giving it a valency of 2 [1]. Nitrogen (N) has a configuration of 2, 5 and requires three electrons to complete its octet, resulting in a valency of 3 [1]. Silicon (Si) has a configuration of 2, 8, 4 and shares four electrons to satisfy its valency, giving it a valency of 4 [1]. Therefore, the correct ascending order of valencies is Ne (0) < Mg (2) < N (3) < Si (4).

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > 3.3 HOW DO METALS AND NON-METALS REA ALS REACT? > p. 47