Given below are two statements : Statement (I) : The correct sequence of bond lengths in the following species is : O_2^+ Statement (II) : The correct sequence of number of unpaired electrons in the following species is : O_2 > O_2^+ > O_2^- > O_2^ 2- In the light of the above statements, choose the correct answer from the options given below :
C. Statement I is true but Statement II is false
The bond order of the given oxygen species can be calculated using molecular orbital theory: For O_2 (16 electrons), the configuration is _ 1s ^2 ^ * _ 1s ^2 _ 2s ^2 ^ * _ 2s ^2 _ 2p_z ^2 _ 2p_x ^2 = _ 2p_y ^2 ^ * _ 2p_x ^1 = ^ * _ 2p_y ^1. Bond order = 10 - 6 2 = 2. Number of unpaired electrons = 2. For O_2^+ (15 electrons), one electron is removed from a ^ * orbital. Bond order = 10 - 5 2 = 2.5. Number of unpaired electrons = 1. For O_2^- (17 electrons), one electron is added to a ^ * orbital. Bond order = 10 - 7 2 = 1.5. Number of unpaired electrons = 1. For O_2^ 2- (18 electrons), two electrons are added to the ^ * orbitals. Bond order = 10 - 8 2 = 1. Number of unpaired electrons = 0. Since bond length is inversely proportional to bond order, the correct sequence of bond lengths is O_2^+ The number of unpaired electrons for the species are 2, 1, 1, and 0 respectively. The correct sequence is O_2 > O_2^+ = O_2^- > O_2^ 2- . Thus, Statement II is false. Answer: Statement I is true but Statement II is false
Related: Chemistry — Chemical Bonding and Molecular Structure · All PYQ Banks