Question

What is meant by octet and duplet? Give exam­ples.

Answer 1

Octet:

1. The outermost shell with eight electrons is known as an octet.
2. Thus, the atoms or ions that have eight electrons in their outermost shell are said to have a complete octet.

Example:

1. Consider a Neon atom $\mathbf{\left(}\mathbf{Ne}\mathbf{\right)}$ having atomic number $10$. Thus, the number of electrons in a Neon atom are $10$.
2. The electronic configuration of Neon atom is $(2,8)$.
3. As there are eight electrons in the outermost shell, Neon atom has a complete duplet.

Duplet:

1. The outermost shell with two electrons is known as a duplet.
2. Thus, the atoms or ions that have two electrons in their outermost shell are said to have a complete duplet.
3. A complete duplet is possible if the atom has only one shell i.e. the first shell which can hold maximum of $2$ electrons.

Example:

1. Consider a Helium atom $\mathbf{\left(}\mathbf{He}\mathbf{\right)}$ having atomic number $2$. Thus, the number of electrons in a Helium atom are $2$.
2. The electronic configuration of Helium atom is $\left(2\right)$.
3. As there are two electrons in the outermost shell, Helium atom has a complete duplet.