Question

How many lone pairs does oxygen have?

Answer 1

Hint :There are two types of electron pairs one is lone pairs and second one is bond pairs. Bond pairs are those electron pairs which do make any bonds or are involved in bonding between atoms whereas lone pairs are those electron pairs which do not make any bonds and are not involved in bonding.

Complete Step By Step Answer:
We know that there are two types of electron pairs present in an atom or a molecule such as lone pairs and bond pairs. The lone pairs are referred to the electron pairs which do not participate in making chemical bonds (covalent bonds) between two atoms. They are also known as unshared pairs of electrons or non-bonding electrons. They are always present in the outermost shell of the atom.
While on the other hand, the bond pairs are the electron pairs which are involved in the chemical bonding (such as making covalent bonds or coordinate bonds) between two atoms or within a molecule.
Now, if we see the oxygen atom, its electronic configuration is:
 $1s^{2}2s^{2}2p^4$
The outermost shell in the oxygen atom is the second shell which includes $2s$ and $2p$ orbitals. It contains six valence shell electrons and hence, there are three valence electron pairs in an oxygen atom.
We know that oxygen forms two bonds and hence two electrons get involved in making those two bonds. So, two electron pairs are left which do not participate in bonding.
Hence, oxygen has two lone pairs.

Note :
We can identify the geometry and shape of a molecule based on the number of bond pairs and number of lone pairs present in the molecule by the VSEPR theory. For example, if a molecule has four bond pairs and no lone pairs, then the molecular geometry and molecular shape of that molecule will be tetrahedral.