What is inert-pair effect?

The inert-pair effect is a phenomenon that occurs in certain elements of the periodic table where the oxidation state of the element is less than expected based on its electron configuration. This is due to the reluctance of the two electrons in the s-orbital of the valence shell to participate in bonding.

This effect is most prominent in the heavy elements of the second and third rows of the periodic table, such as lead, tin, and bismuth. These elements tend to form compounds where they have a lower oxidation state, such as +2 instead of +4 or +5.

The inert-pair effect can be attributed to the increasing stability of the s-electrons as the atomic number of the element increases. This stability makes it harder for the s-electrons to participate in chemical reactions, leading to a tendency for the element to form compounds with a lower oxidation state.

The inert-pair effect has important implications for the properties and behavior of these heavy elements in chemical reactions and is an area of ongoing research.