Question

Construct the molecular orbital diagram for He2 and then identify the bond order. Bond order: Click within the blue boxes to add electrons.

Answer 1

Concepts and reason

Bond order is the number, which indicates the total number of bonds present between two atoms. Bond order describes the bond strength of the molecule;

If the bond order is more, the bond strength would also be more for that molecule.

${\rm{Bond Order}} \propto {\rm{Bond}}\,{\rm{strength}}$ .

Fundamentals

Bond order calculation:

$\begin{array}{l}\\{\rm{B}}{\rm{.O}}\,{\rm{ = }}\frac{{\,{\rm{1}}}}{{\rm{2}}}{\rm{(B}}{\rm{.E - A}}{\rm{.B}}{\rm{.E)}}\\\\{\rm{Where,}}\\\\{\rm{B}}{\rm{.O}}\,{\rm{ = }}\,{\rm{Bond}}\,{\rm{order}}{\rm{.}}\\\\{\rm{B}}{\rm{.E}}\,{\rm{ = }}\,{\rm{Bonding}}\,{\rm{electrons}}{\rm{.}}\\\\{\rm{A}}{\rm{.B}}{\rm{.E}}\,{\rm{ = }}\,{\rm{Anti - bonding}}\,{\rm{electrons}}{\rm{.}}\\\end{array}$

The general molecular orbital diagram is shown below.

The given molecule is ${\rm{H}}{{\rm{e}}_{\rm{2}}}$ which has 4 electrons in it.

Molecular orbital diagram for the molecule ${\rm{H}}{{\rm{e}}_{\rm{2}}}$ is shown below.

The given molecule is ${\rm{H}}{{\rm{e}}_{\rm{2}}}$ .

The number of bonding electrons in ${\rm{H}}{{\rm{e}}_{\rm{2}}}$ molecule is 2

The number of anti-bonding electrons in ${\rm{H}}{{\rm{e}}_{\rm{2}}}$ molecule is 2

Now,

$\begin{array}{l}\\{\rm{B}}{\rm{.O}}\,{\rm{ = }}\,\,\frac{{\,{\rm{1}}}}{{\rm{2}}}{\rm{(B}}{\rm{.E - A}}{\rm{.B}}{\rm{.E)}}\,\\\\\,\,\,\,\,\,\,\,\,{\rm{ = }}\,\,\frac{{\,{\rm{1}}}}{{\rm{2}}}{\rm{(2 - 2)}}\\\\\,\,\,\,\,\,\,\,{\rm{ = }}\,\,\frac{{\,{\rm{1}}}}{{\rm{2}}}{\rm{(0)}}\\\\\,\,\,\,\,\,\,\,{\rm{ = }}\,\,{\rm{0}}\\\end{array}$

Therefore, the bond order for the given molecule ${\rm{H}}{{\rm{e}}_{\rm{2}}}$ is zero.

Ans:

Bond order and the molecular orbital of the diagram is given below.