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NEET-XI-Chemistry

04: Chemical Bonding and Molecular Structure

 page 3
Qstn# 40 Prvs-Qstn
  • #40
    What is meant by the term bond order? Calculate the bond order of: N2, O2, and.
    Ans : Bond order is defined as one half of the difference between the number of electrons present in the bonding and anti-bonding orbitals of a molecule.

    If Na is equal to the number of electrons in an anti-bonding orbital, then Nb is equal to the number of electrons in a bonding orbital.

    Bond order =

    If Nb > Na, then the molecule is said be stable. However, if Nb ≤ Na, then the molecule is considered to be unstable.

    Bond order of N2 can be calculated from its electronic configuration as:



    Number of bonding electrons, Nb = 10

    Number of anti-bonding electrons, Na = 4

    Bond order of nitrogen molecule

    = 3

    There are 16 electrons in a dioxygen molecule, 8 from each oxygen atom. The electronic configuration of oxygen molecule can be written as:



    Since the 1s orbital of each oxygen atom is not involved in boding, the number of bonding electrons = 8 = Nb and the number of anti-bonding electrons = 4 = Na.

    Bond order



    = 2

    Hence, the bond order of oxygen molecule is 2.

    Similarly, the electronic configuration of can be written as:



    Nb = 8

    Na = 3

    Bond order of

    = 2.5

    Thus, the bond order of is 2.5.

    The electronic configuration of ion will be:



    Nb = 8

    Na = 5

    Bond order of =

    = 1.5

    Thus, the bond order of ion is 1.5.