Question

What are the number of bonding pairs and lone pairs of electrons in `H_2O`?

Answer 1

2 bonding pairs and 2 lone pairs

Explanation:

Bonding pair is a pair of electrons that is shared by two atoms to form a covalent bond. Lone pairs on the other hand are pairs of electrons that do not take part in bonding.

To identify which is which, you have to write down the Lewis structure. The Lewis structure of water is found below.

(Reference: biochemhelp.com)

In the case of `H_2O`, Oxygen, the central atom, has a total of 6 valence electrons or outer shell electrons. This means that it will need another two electrons to satisfy the octet rule.

Since, there are two Hydrogen attached to a single Oxygen we can say that `H_2O` has two bonding pairs as well. Remember that Oxygen has six valence electron then you take two electrons to be shared with two Hydrogen. This leaves us with four electrons that do not participate in the bonding. Therefore, it has two lone pairs

Two atoms bonded to the central atom, Oxygen = Two bonding pairs
Four electrons that do not participate in bonding = Two lone pairs