Question

Use the LE model to describe the bonding in ${\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{O}$and ${\mathit{C}}_{\mathbf{2}}{\mathit{H}}_{\mathbf{2}}$.Carbon is the central atom in ${\mathit{H}}_{\mathbf{2}}\mathit{C}\mathit{O}$and ${\mathit{C}}_{\mathbf{2}}{\mathit{H}}_{\mathbf{2}}$exist as HCCH.

Short answer

The central carbon in ${\text{H}}_{\text{2}}\text{CO}$ is $s{p}^2$ hybridized. The three hybrid orbitals are formed from the combination of one 2s and two 2p orbital of carbon. The three hybrid orbitals form three sigma bond. The unhybridized p orbital forms the pi bond between carbon and oxygen.

The central carbon in $C_2{H}_2$ is sp hybridized. The two sp hybrid orbitals are formed from the combination of one 2s and one 2p orbital. The two hybrid orbitals form the sigma bond. While the two 2p unhybridized orbital form the two pi bonds.

Step-by-step solution

Step 1

The Lewis structure is as follows:

Hence the carbon is $s{p}^2$ hybridized and is trigonal planar.

Each carbon has three $s{p}^2$ hybrid orbitals and one unhybridized p orbital.

The three $s{p}^2$ hybrid orbitals form three σ bonds and the unhybridized p orbital forms the π bond with oxygen atom.

Step 2

The Lewis structure for ethyne is

Each carbon is $sp$hybridized and the structure of the molecule is linear.

Each carbon has two sp hybrid orbital and two unhybridized p orbital which overlap with hydrogen to form the two π bonds.