Question

Why neon, helium and argon have zero valences?

Answer 1

Valency:

The combining capacity of the atom of an element with the atoms of other elements in order to acquire eight electrons (or two electrons in Helium) in its outermost shell is known as valency.

Zero valency:

1. When an atom does not gain or lose or share electrons in its outermost shell its valency becomes zero.
2. The atom has its outermost shell completely filled and thus, it does not gain or lose or share electrons.
3. Such atoms having valency zero are known as zerovalent.

Zero valency of Neon $\mathbf{\left(}\mathbf{Ne}\mathbf{\right)}$:

1. Neon has atomic number $10$. Thus, the electronic configuration of Neon is $(2,8)$.
2. The outermost shell of Neon has eight electrons i.e. it has a complete octet.
3. Thus, Neon does not gain or lose or share electrons.
4. Thus, valency of Neon is zero and it is known as zerovalent.

Zero valency of Helium $\mathbf{\left(}\mathbf{He}\mathbf{\right)}$:

1. Helium has atomic number $2$. Thus, the electronic configuration of Helium is $\left(2\right)$.
2. The outermost shell of Helium has two electrons i.e. it has a complete duplet.
3. Thus, Helium does not gain or lose or share electrons.
4. Thus, valency of Helium is zero and it is known as zerovalent.

Zero valency of Argon $\mathbf{\left(}\mathbf{Ar}\mathbf{\right)}$:

1. Argon has atomic number $18$. Thus, the electronic configuration of Argon is $(2,8,8)$.
2. The outermost shell of Argon has eight electrons i.e. it has a complete octet.
3. Thus, Argon does not gain or lose or share electrons.
4. Thus, valency of Argon is zero and it is known as zerovalent.