Chemical Bonding And Molecular Structure
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According to MO theory which of the following lists ranks the nitrogen species in terms of increasing bond order?
A.
Bond Order = 
Where
Nb = number of electrons in bonding MO
Na = number of electrons in antibonding MO
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Bond dissociation enthalpy of H2, Cl2 and HCl and 434, 242 and 431 kJ mol-1 respectively. Enthalpy of formation of HCl is
-
93 kJ mol-1
-
-245 kJ mol-1
-
-39 kJ mol-1
-
245 kJ mol-1
C.
-39 kJ mol-1
Bond order of 1.5 is shown by
-
O2+
-
O2-
-
O22-
-
O2
B.
O2-
MO configuration of O2+ (8+8-1=15)
Consider the following compounds
Hyperconjugation occurs in
-
I only
-
II only
-
III only
-
I and III
C.
III only
Hyperconjugation occurs through the H- atoms present on the carbon atom next to the double bond i.e alpha hydrogen atoms. There is no alpha -H in the structure I and II.
So, hyperconjugation occurs in structure III only ie. 
Consider the molecules CH4, NH3 and H2O. Which of the given statement is false?
-
The H-O-H bond angle in H2O is larger than the H-C-H bond angle in CH4.
-
The H-O-H bond angle in H2O is smaller than the H-N-H bond angle in NH3.
-
The H-C-H bond angle in CH4 is larger than the H-N-H bond angle in NH3
-
The H-C-H bond angle in CH4, the H-N-H bond angle in H2O are all greater than 900.
A.
The H-O-H bond angle in H2O is larger than the H-C-H bond angle in CH4.
According to VBT: lone pair-lone pair repulsion is more than a bond pair -lone pair repulsion.
As the number of lone pair of electrons on central element increases, repulsion between that lone pair of electrons increases and therefore, bond angle decreases.
|
Molecules |
Bond angle |
|
CH4 (no lone pair of electrons) |
1090.5 |
|
NH3(one lone pair of electrons) |
107.50 |
|
H2O (two lone pair of electrons) |
104.450 |
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