Question

How do you calculate the number of valence electrons in neon?

Answer 1

Hint Valency is defined as the combining capacity of the elements, and valency of an atom is determined by the number of valence electrons present in the outermost shell of the atom. In an atom only the outer shell electrons take part in chemical combination and these electrons are known as valence electrons. In Lewis symbols the number of dots around the symbol represents the number of valence electrons. Neon belongs to the $\text{1}{\text{8}}^{\text{th}}$ group of the periodic table, and general electronic configuration of $\text{1}{\text{8}}^{\text{th}}$ group element is $\text{n}{\text{s}}^{\text{2}}\text{n}{\text{p}}^{\text{6}}\text{(except}\text{He)}$.

Complete Step by step solution –
The calculation of the number of valence electrons in an atom is determined by counting the number of electrons present in the outer (valence) shell configuration of the atom.
Atomic number of neon is $10$, so its electronic configuration is $\text{1}{\text{s}}^{\text{2}}\text{2}{\text{s}}^{\text{2}}\text{2}{\text{p}}^{\text{6}}$. Hence, the number of valence electrons is $2e+6e=8e$.
The number of valence shell electrons in neon is $8$.

Additional information –
Valency represents the number of electrons gained or lost or shared with other atoms in the formation of compounds. Valency of elements in the periodic table varies from$1-8$. Valency of elements is based on electronic configuration. Valency of elements in group $1$and $2$elements is equal to the number of valence electrons, while that for groups $13$and $14$ is group number minus $10$. In the group $15-18$ valency is $\text{(8-}\text{no}\text{of}\text{valence}\text{electrons)}$.

Note – All the elements of a group have the same valences because they have the same number of valence electrons. Orbitals containing valence electrons are called valence shell orbitals, and to form a covalent bond overlapping occurs between half-filled valence shell orbitals of the two atoms.