Question

Explain the formation of $B{F}_3$ molecules using hybridisation.
[2 Marks]

Answer 1

Hybridisation is the process of intermixing the orbitals of slightly different energies to form a new set of orbitals of equivalent energies and shapes.
[0.5 Marks]
The ground state electronic configuration of Be is $1s^{2}2s^{2}2p^1$. In the excited state, one of the 2s-electrons is promoted to the vacant 2p orbital.
[0.5 Marks]
One 2s and two 2p-orbital get hybridised to form three $s{p}^2$ hybridised orbitals. These three $s{p}^2$ hybrid orbitals are oriented in opposite directions forming an angle of 120°.
[0.5 Marks]
Each of the $s{p}^2$ hybridised orbital overlaps with the 2p-orbital of fluorine atoms axially and forms two Be-Cl sigma bonds.
[0.5 Marks]
\( \begin{array}{l}{ }_{9}=-\frac{1 l}{2 s} \quad \begin{array}{|c|c|c|}\hline 11 & 1 l & 1 \\ 2 p_{x} & 2 p_{y} & 2 p_{z}\end{array} \\ sp ^{2} \text { hybridisation } \\\end{array} \)