Organic Chemistry Basics 2 Question 20
«««< HEAD
20. In allene $\left(\mathrm{C}{3} \mathrm{H}{4}\right)$, the type(s) of hybridisation of the carbon atoms, is (are)
======= ####20. In allene $\left(\mathrm{C}{3} \mathrm{H}{4}\right)$, the type(s) of hybridisation of the carbon atoms, is (are)
3e0f7ab6f6a50373c3f2dbda6ca2533482a77bed (a) $s p$ and $s p^{3}$
(b) $s p$ and $s p^{2}$
(c) only $s p^{3}$
(d) $s p^{2}$ and $s p^{3}$
(2012)
Show Answer
Solution:
- Allene is the name given to propdiene, $\mathrm{H}{2} \mathrm{C}=\mathrm{C}=\mathrm{CH}{2}$
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 number of lone pairs at the concerned atom.
$\operatorname{Pi}(\pi)$ 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 $s p^{3}$. The central carbon has only two sigma bonds associated, hence hybridisation at central carbon is $s p$.
