Question
Which of the following statements is not correct from the view point of molecular orbital theory?
A.
$$B{e_2}$$ is not a stable molecul.
B.
$$H{e_2}$$ is not stable but $$He_2^ + $$ is expected to exist.
C.
Bond strength of $${N_2}$$ is maximum amongst the homonuclear diatomic molecules belonging to the second period.
D.
The order of energies of molecular orbitals in $${N_2}$$ molecule is $$\sigma 2s < {\sigma ^ * }2s < \sigma 2{p_z} < $$ $$\left( {\pi 2{p_x} = \pi 2{p_y}} \right) < \left( {{\pi ^ * }2{p_x} = {\pi ^ * }2{p_y}} \right)$$ $$ < {\sigma ^ * }2{p_z}$$
Answer :
The order of energies of molecular orbitals in $${N_2}$$ molecule is $$\sigma 2s < {\sigma ^ * }2s < \sigma 2{p_z} < $$ $$\left( {\pi 2{p_x} = \pi 2{p_y}} \right) < \left( {{\pi ^ * }2{p_x} = {\pi ^ * }2{p_y}} \right)$$ $$ < {\sigma ^ * }2{p_z}$$
Solution :
The correct order of energies of molecular orbitals in $${N_2}$$ molecule is $$KK\sigma 2s < {\sigma ^ * }2s < \left( {\pi 2{p_x} = \pi 2{p_y}} \right)$$ $$ < \sigma 2{p_z} < \left( {{\pi ^ * }2{p_x} = {\pi ^ * }2{p_y}} \right) < {\sigma ^ * }2{p_z}$$