Question

In allene (${C_3}{H_4}$), the type(s) of hybridization of the carbon atom is (are):
A. $s{p^2}$ and $sp$
B. $s{p^2}$ and $s{p^3}$
C. $sp$and $s{p^3}$
D. only $s{p^2}$

Answer 1

Hint: The structures which have a double bond have $s{p^2}$ hybridization and they have trigonal planar geometry. But if the structure has a triple bond equivalent in it with a linear structure, it has a $sp$ hybridization. The $s{p^3}$ hybridization has a tetrahedral geometry.

Complete answer:
 Allene is an organic compound that comprises 3 carbon atoms attached to each other with the help of 3 double bonds. The structure of allene is as follows:

In the structure, the 1st and the 3rd carbon atoms have a trigonal planar geometry with bond angle of ${120^o}$ in space. The two hydrogen atoms are connected to the 1st and 3rd carbon with the help of a $\sigma - bond$ . Thus, the first and third carbon atoms have $s{p^2}$hybridization.
Now, let us talk about the central carbon attached with the first and third carbon on both the sides. The central carbon has two $\sigma - bonds$and two $\pi - bonds$altogether. Thus, it acts as a triple bond equivalent with 1 sigma bond and 2 pi-bonds. Thus, the central carbon atom has $sp$ hybridization and the $C = C = C$ bond is linear in shape.
Overall, allene has both $s{p^2}$ and $sp$ hybridization.

Thus, the correct option is A. $s{p^2}$ and $sp$.

Note:
Allene is found naturally in various coloring pigments such as fucoxanthin and peridinin. They are primarily used as ligands in organometallic chemistry. It is also used as a catalyst in various organic synthesis reactions. In allenes, only one of the pairs of the double bonds is reducible.