Question

How many sigma and pi bonds are present in a molecule of cumulene? (Figure 1) Enter the number of sigma bonds followed by the number of pi bonds separated by a comma. What types of orbital overlap occur in cumulene? Check all that apply.

Answer 1

Concepts and reason

Sigma bond: It is a type of covalent bond where there is head-on overlapping of orbitals. It is the strongest form of covalent bonding. Sigma bonds can rotate freely.

Pi bond: It is a type of covalent bond where there is parallel or side-way overlapping of orbitals. The bond is not as strong as a sigma bond. Free rotation is not possible here.

Cumulene: It is a hydrocarbon having three or more number of consecutive double bonds.

Fundamentals

Covalent bonding is the bonding between two atoms due to the mutual sharing of electrons between them.

The single bond formed between any two atoms is a sigma bond. If multiple bonds are present, it means that one is sigma and the others are pi-bonds.

Hybridization is the mixing of atomic orbitals of different energies to form an equal number of new hybrid orbitals. There are different types of hybrid orbitals.

• sp

• sp²

• sp³

• sp³d

• sp³d²

• sp³d³

(A)

The number of σ- and π-bonds in cumulene is shown below:

(B)

The wrong options are given below:

The right choices are given below:

Ans: Part A

The number of σ and π-bonds is as follows:

Part B

The orbital overlaps in cumulene are as follows: