Question

Account for the following:
(i) $He_{2}$ is not found to exist in nature.
(ii) $N_{2}^{+}$ is not a diamagnetic substance.
(iii) The dissociation energy of $He_{2}^{+}$ is almost the same as that of $He_{2}^{+}$.

Answer 1

i) $He_{2}$ is an “inert gas” with zero Valency, since its octet is filled completely.

${ He }_{ 2 }$  electronic configuration is $1{ s }^{ 2 }$  and molecular orbital electronic configuration is $\sigma { 1s }^{ 2 }{ \sigma  }^{ \ast  }{ 1s }^{ 2 }$.

Thus, the order of bond becomes nullified since the “number of electrons” in “bonding” and “anti-bonding” orbitals is equal.

Now, since the bond order becomes zero in a ${ He }_{ 2 }$  molecule, it does not exist naturally.

ii) Most of the molecules/atoms are diamagnetic but it becomes paramagnetic due to the presence of electrons that are unpaired which induces magnetism. As per the molecular orbital electronic configuration, ${ N }_{ 2 }$  has a total of 13 electrons, which results in a single unpaired electron in the $\sigma 2{ p }_{ Z }$ molecular orbital, which makes it paramagnetic.

iii) The bond-dissociation energy and bond order is related directly. The bond association energy does not differ from bond energy in diatomic molecules.

Hence in ${ H }_{ 2 }$  and ${ He }_{ 2 }$  molecules, the bond order remains the same at $\frac { 1 }{ 2 }$ and the bond association energy also is same.

Answer 2

.
 He_{2}He2​ is an “inert gas” with zero Valency, since its octet is filled completely.

{ He }_{ 2 }He2​  electronic configuration is 1{ s }^{ 2 }1s2 and molecular orbital electronic configuration is  .

Thus, the order of bond becomesnullified since the “number of electrons” in “bonding” and “anti-bonding” orbitals is equal.

Now, since the bond order becomes zero in a { He }_{ 2 }He2​  molecule, it does not exist naturally.

ii) Most of the molecules/atoms are diamagnetic but it becomesparamagnetic due to the presence of electrons that are unpaired which induces magnetism. As per the molecular orbital electronic configuration, { N }_{ 2 }N2​  has a total of 13 electrons, which results in a single unpaired electron in the \sigma 2{ p }_{ Z }σ2pZ​molecular orbital, which makes it paramagnetic.

iii) The bond-dissociation energy and bond order is related directly. The bond association energy does not differ from bond energy in diatomic molecules.

Hence in { H }_{ 2 }H2​  and { He }_{ 2 }He2​  molecules, the bond order remains the same at \frac { 1 }{ 2 }21​ andthe bond association energy also is same.

 He_{2}He2​ is an “inert gas” with zero Valency, since its octet is filled completely.

{ He }_{ 2 }He2​  electronic configuration is 1{ s }^{ 2 }1s2 and molecular orbital electronic configuration is  .

Thus, the order of bond becomesnullified since the “number of electrons” in “bonding” and “anti-bonding” orbitals is equal.

Now, since the bond order becomes zero in a { He }_{ 2 }He2​  molecule, it does not exist naturally.

ii) Most of the molecules/atoms are diamagnetic but it becomesparamagnetic due to the presence of electrons that are unpaired which induces magnetism. As per the molecular orbital electronic configuration, { N }_{ 2 }N2​  has a total of 13 electrons, which results in a single unpaired electron in the \sigma 2{ p }_{ Z }σ2pZ​molecular orbital, which makes it paramagnetic.

iii) The bond-dissociation energy and bond order is related directly. The bond association energy does not differ from bond energy in diatomic molecules.

Hence in { H }_{ 2 }H2​  and { He }_{ 2 }He2​  molecules, the bond order remains the same at \frac { 1 }{ 2 }21​ andthe bond association energy also is same.

 He_{2}He2​ is an “inert gas” with zero Valency, since its octet is filled completely.

{ He }_{ 2 }He2​  electronic configuration is 1{ s }^{ 2 }1s2 and molecular orbital electronic configuration is  .

Thus, the order of bond becomesnullified since the “number of electrons” in “bonding” and “anti-bonding” orbitals is equal.

Now, since the bond order becomes zero in a { He }_{ 2 }He2​  molecule, it does not exist naturally.

ii) Most of the molecules/atoms are diamagnetic but it becomesparamagnetic due to the presence of electrons that are unpaired which induces magnetism. As per the molecular orbital electronic configuration, { N }_{ 2 }N2​  has a total of 13 electrons, which results in a single unpaired electron in the \sigma 2{ p }_{ Z }σ2pZ​molecular orbital, which makes it paramagnetic.

iii) The bond-dissociation energy and bond order is related directly. The bond association energy does not differ from bond energy in diatomic molecules.

Hence in { H }_{ 2 }H2​  and { He }_{ 2 }He2​  molecules, the bond order remains the same at \frac { 1 }{ 2 }21​ andthe bond association energy also is same