Question

In he2 the electrons in bonding and antibonding orbitals are

Answer 1

In He2, the electronic configuration will be
$\alpha s2 \: \alpha.s2$
i.e. there will be two bonding electrons and two anti bonding electrons. Such a molecule won't exist since bond order would be zero

Answer 2

In He₂, there are two electrons in the bonding orbital and two electrons in the antibonding orbital.

• Each He atom has a single atomic orbital available which is 1s.
• After generating molecular orbitals, there are 4 total electrons available in a He₂ molecule in total.
• The resulting Molecular Orbital is 1s² 1s*²
• Two electrons are in bonding orbitals and two electrons are in antibonding orbitals.
• Bond Order equals $\frac{1}{2}$ times the difference between the electrons in bonding orbitals and the electrons in antibonding orbitals.
• Thus, Bond Order = $\frac{Nb-Na}{2}$

                                       = $\frac{2-2}{2}$

                                       = 0

• Because the bond order is zero, the He₂ molecule does not exist.