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Chemical Bonding And Molecular Structure

Question
CBSEENCH11005787

Using a molecular orbital diagram, predict the bond order, stability and magnetic character of O2,O2+, and straight O subscript 2 superscript 2 minus end superscript left parenthesis peroxide space ion right parenthesis . Also, write their electronic configurations.

Solution

O2(Superoxide ion): This ion is formed by the addition of one electron.
O2 + e- → O2
This additional electron will be added up in the straight pi asterisk times 2 straight p subscript straight x space space space or space space straight pi asterisk times 2 straight p subscript straight y molecular orbital.
Electronic configuration:
straight O subscript 2 superscript minus colon space space left square bracket KK space left parenthesis straight sigma 2 straight s right parenthesis squared space left parenthesis straight sigma asterisk times 2 straight s right parenthesis squared space left parenthesis straight pi 2 straight p subscript straight z right parenthesis squared space left parenthesis straight pi 2 straight p subscript straight x right parenthesis squared space left parenthesis straight pi 2 straight p subscript straight y right parenthesis squared space left parenthesis straight pi asterisk times 2 straight p subscript straight x right parenthesis squared space left parenthesis straight pi asterisk times 2 straight p subscript straight y right parenthesis to the power of 1 right square bracket
Bond order:
Here Nb = 8;   Na = 5
Bond space order space equals space 1 half open square brackets straight N subscript straight b space minus straight N subscript straight a close square brackets
space space space space space space space space space space space space space space space space equals space 1 half left parenthesis 8 minus 5 right parenthesis space equals space 3 over 2 equals space 1 1 half
Stability : As the bond order is positive, it is quite stable.
Magnetic character: It has one unpaired electron in the straight pi asterisk times 2 straight p subscript straight y molecular orbital. 
therefore, it is paramagnetic.
O+2 ion  This ion is formed by the loss of one electron from O2 molecule.
O2 →O2+ e
This electron will be lost from straight pi*2px or straight pi*2py molecular orbital.
Electronic configuration:
straight O subscript 2 superscript plus semicolon space space open square brackets KK space left parenthesis straight sigma 2 straight s right parenthesis squared space left parenthesis straight sigma asterisk times 2 straight s right parenthesis squared space left parenthesis straight sigma 2 straight p subscript straight z right parenthesis squared space left parenthesis straight pi 2 straight p subscript straight x right parenthesis squared space left parenthesis straight pi 2 straight p subscript straight y right parenthesis squared space left parenthesis straight pi asterisk times 2 straight p subscript straight x right parenthesis to the power of 1 close square brackets
Bond order:  Here Nb = 8;    Na = 3
Bond space order space equals space 1 half open square brackets straight N subscript straight b space minus space straight N subscript straight a close square brackets space space equals space 1 half left parenthesis 8 minus 3 right parenthesis space equals 5 over 2 space equals 2 1 half
space
Stability: As the bond order is positive, it is quite stable.
Magnetic character: Since straight O subscript 2 superscript plus ion has one unpaired electron in the straight pi asterisk times 2 straight p subscript straight x orbital, therefore, it is paramagnetic.
straight O subscript 2 superscript 2 minus end superscript left parenthesis peroxide space ion right parenthesis: The ion is formed when O2 molecule gains two electrons
straight O subscript 2 plus 2 straight e to the power of minus space rightwards arrow space straight O subscript 2 superscript 2 minus end superscript
These two electrons will be added to the straight pi*2px and straight pi*2py molecular orbitals, one in each.
Electronic configuration:
straight O subscript 2 superscript 2 minus end superscript colon space space open square brackets KK space left parenthesis straight sigma 2 straight s right parenthesis squared space left parenthesis straight sigma asterisk times 2 straight s right parenthesis squared space left parenthesis straight sigma 2 straight p subscript straight z right parenthesis squared space left parenthesis straight pi 2 straight p subscript straight x right parenthesis squared space left parenthesis straight pi 2 straight p subscript straight y right parenthesis squared space left parenthesis straight pi asterisk times 2 straight p subscript straight x right parenthesis squared space left parenthesis straight pi asterisk times 2 straight p subscript straight y right parenthesis squared close square brackets
Bond order: Here Nb = 8;    Na = 6
Bond space order space equals space 1 half open square brackets straight N subscript straight b minus straight N subscript straight a close square brackets space equals space 1 half left parenthesis 8 minus 6 right parenthesis space equals space 1

Stability: As the bond order is positive, it is quite stable.
Magnetic character: As one of the molecular orbital has a unpaired electron, it is diamagnetic.