Question

CHEMICAL BONDING Counting sigma and pi bonds in a small molecule Answer the questions below about the highlighted atom in this Lewis structure: H :0: H -C-C-H H In how many sigma bonds does the highlighted atom participate? In how many pi bonds does the highlighted atom participate? What is the orbital hybridization of the highlighted atom? TU

Answer 1

If there are more than one chemical bonds present between two atoms then there will be one sigma bond and remaining bonds will be pi bond. For example if there are two bonds present then one sigma bond and one one pi bond,

If three bonds present then one sigma two pi bond.

there will be always only one sigma bonds between two atom.

In given molecule there are two bonds between highlighted atom (oxygen atom )and Carbon atom thus

Number of sigma bond=1, and

Number of pi bond = 2-1= 1

H​​​​​​​ybridization of atom is determined by counting number of hybridized atomic orbitals (number of sigma bond and non bonding electron pair/lone pair). In hybridization pi bonds are not considered as they are formed by unhybridizes orbitals.

Consider the given table

Number of hybridized atomic orbitals	Hybridization
2	sp
3	sp2
4	sp3
5	sp3d
6	sp3d2
7	sp3d3

For highlighted atom number of hybridized atomic orbitals= 3( one sigma bond two lone pair)

Hybridization will be sp2.