Question

In allene $\left(C_3{H}_4\right),$ the type(s) of hybridisation of the carbon atoms, is (are)

• A. sp and $s{p}^3$
• B. sp and $s{p}^2$
• C. only $s{p}^3$
• D. $s{p}^{2}ands{p}^3$

Answer 1

The correct option is B sp and $s{p}^2$

Allene is the name given to propdiene, $\underset{Allene}{H_{2}C=C=C{H}_2}.$
Hybridisation of an atom is determined by determining the number of hybrid orbitals at that atom which is equal to the number of sigma ($\sigma$) bonds plus nubmer of lone pairs at the concerned atom.

Pi($\pi$) bonds are not formed by hybrid orbitals, therefore, not counted for hybridisation.

Here, the terminal carbons have only three sigma bonds associated with them, therefore, hybridisation of terminal carbons is $s{p}^2$ The central carbon has only two sigma bonds associated, hence hybridisation at central carbon is $sp$