The distribution of electrons among molecular orbitals is called the electronic configuration of the molecule which provides us the following very imp
The distribution of electrons among molecular orbitals is called the electronic configuration of the molecule which provides us the following very important informations about the molecule.
(A)Stability of molecule : The molecule is stable if number of bonding moleculer orbital electrons `(N_b)` is greater than the number of antibonding molecular orbital electrons `(N_a)`.
(B) Bond order : Bond order `=1/2(N_b-N_a)`
A positive bond order means a stable molecule while a negative or zero bond order means an unstable molecule.
( C)Nature of the bond : Bond order 1,2 and 3 corresponds to single , double and triple bonds respectively.
(D)Bond length: Bond length decreases as bond order increases.
(E)Magnetic nature: Molecular orbitals in a molecule are doubly occupied , the substance is diamagnetic and if one or more molecular orbitals are singly occupied, it is paramagnetic.
Which of the following statements is incorrect ?
A. Among `O_2^(+),O_2` and `O_2^(-)` the bond length decreases as `O_2^(-) gt O_2 gt O_2^(+)`
B. `He_2` molecule does not exist as the bonding and anti-bonding orbitals cancel each other
C. `C_2, O_2^(2+)` and `Li_2` are dimagnetic
D. In `F_2` molecule the energy of `sigma_(2p_z)` is more than `pi_2p_x` and `pi_2p_y`
1 Answers
Correct Answer - D
(A)Bond order `prop 1/("bond length")`
Bond order `O_2^+=2.5, O_2=2 O_2^(-)=1.5`
so correct order of bond length is `O_2^(-) gt O_2 gt O_2^+`
(B)Bond order for `He_2=(2-2)/2=0` So `He_2` does not exist.
(C )In all these molecules all electrons all electrons are paired in molecular orbitals. So they are all diamagnetic
(D)`F_2`MOT configuration :
`sigma1s^2sigma^**1s^2sigma2s^2sigma^**2s^2sigma2p_z^2pi2p_y^2pi2p_z^2pi^**2p_y^2pi^**2p_z^2pi^**2p_z^2sigma^**2p_z^@`