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64
Subjective

(a) Discuss the concept of hybridisation. What are its different types in a carbon atom?

(b) What is the type of hybridisation of carbon atoms marked with star?

Explanation

Hybridisation It can be defined as the process of intermixing of the orbitals of slightly different energy or of same energy to produce entirely new orbitals of equivalent energy, identical shapes and symmetrically disposed in plane. New orbitals formed are called hybrid orbitals.

Only the orbitals of an isolated single atom can undergo hybridisation. The hybrid orbitals generated are equal in number to that of the pure atomic orbitals which mix up.

Hybrid orbitals do not make $\pi$, pi-bonds. If there are $\pi$-bonds, equal number of atomic orbitals must be left unhybridised for $\pi$-bonding.

Like atomic orbitals, hybrid orbitals cannot have more than two electrons of opposite spins. Types of hybridisation in carbon atoms

(a) (i) Diagonal or sp-hybridisation All compounds of carbon containing $\mathrm{C} \equiv \mathrm{C}$ triple bond like ethyne $\left(\mathrm{C}_2 \mathrm{H}_2\right)$.

(ii) Trigonal or $\mathrm{sp}^2$-hybridisation All compounds of carbon containing $\mathrm{C}=\mathrm{C}$ (double bond) like ethene $\left(\mathrm{C}_2 \mathrm{H}_4\right)$.

(iii) Tetrahedral or $\mathrm{sp}^3$-hybridisation All compounds of carbon containing $\mathrm{C}-\mathrm{C}$ single bonds only like ethane $\left(\mathrm{C}_2 \mathrm{H}_6\right)$.

65
MCQ (Single Correct Answer)

Molecular orbitals are formed by the overlap of atomic orbitals. Two atomic orbitals combine to form two molecular orbitals called bonding molecular orbital (BMO) and anti-bonding molecular orbital (ABMO). Energy of anti-bonding orbital is raised above the parent atomic orbitals that have combined and the energy of the bonding orbital is lowered than the parent atomic orbitals.

Energies of various molecular orbitals for elements hydrogen to nitrogen increase in the order

$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\sigma 2 p_z<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$ and

For oxygen and fluorine order of energy of molecular orbitals is given below

$$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\sigma p_z<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$$

Different atomic orbitals of one atom combine with those atomic orbitals of the second atom which have comparable energies and proper orientation.

Further, if the overlapping is head on, the molecular orbital is called 'sigma', ( $\sigma$ ) and if the overlap is lateral, the molecular orbital is called 'pi', $(\pi)$. The molecular orbitals are filled with electrons according to the same rules as followed for filling of atomic orbitals.

However, the order for filling is not the same for all molecules or their ions. Bond order is one of the most important parameters to compare the strength of bonds.

Which of the following statements is correct?

A
In the formation of dioxygen from oxygen atoms 10 molecular orbitals will be formed
B
All the molecular orbitals in the dioxygen will be completely filled
C
Total number of bonding molecular orbitals will not be same as total number of anti-bonding orbitals in dioxygen
D
Number of filled bonding orbitals will be same as number of filled anti-bonding orbitals
66
MCQ (Single Correct Answer)

Molecular orbitals are formed by the overlap of atomic orbitals. Two atomic orbitals combine to form two molecular orbitals called bonding molecular orbital (BMO) and anti-bonding molecular orbital (ABMO). Energy of anti-bonding orbital is raised above the parent atomic orbitals that have combined and the energy of the bonding orbital is lowered than the parent atomic orbitals.

Energies of various molecular orbitals for elements hydrogen to nitrogen increase in the order

$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\sigma 2 p_z<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$ and

For oxygen and fluorine order of energy of molecular orbitals is given below

$$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\sigma p_z<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$$

Different atomic orbitals of one atom combine with those atomic orbitals of the second atom which have comparable energies and proper orientation.

Further, if the overlapping is head on, the molecular orbital is called 'sigma', ( $\sigma$ ) and if the overlap is lateral, the molecular orbital is called 'pi', $(\pi)$. The molecular orbitals are filled with electrons according to the same rules as followed for filling of atomic orbitals.

However, the order for filling is not the same for all molecules or their ions. Bond order is one of the most important parameters to compare the strength of bonds.

Which of the following molecular orbitals has maximum number of nodal planes?

A
$\sigma^* 1 s$
B
$\sigma^* 2 p_z$
C
$\pi 2 p_x$
D
$\pi^* 2 p_y$
67
MCQ (Single Correct Answer)

Molecular orbitals are formed by the overlap of atomic orbitals. Two atomic orbitals combine to form two molecular orbitals called bonding molecular orbital (BMO) and anti-bonding molecular orbital (ABMO). Energy of anti-bonding orbital is raised above the parent atomic orbitals that have combined and the energy of the bonding orbital is lowered than the parent atomic orbitals.

Energies of various molecular orbitals for elements hydrogen to nitrogen increase in the order

$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\sigma 2 p_z<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$ and

For oxygen and fluorine order of energy of molecular orbitals is given below

$$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\sigma p_z<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$$

Different atomic orbitals of one atom combine with those atomic orbitals of the second atom which have comparable energies and proper orientation.

Further, if the overlapping is head on, the molecular orbital is called 'sigma', ( $\sigma$ ) and if the overlap is lateral, the molecular orbital is called 'pi', $(\pi)$. The molecular orbitals are filled with electrons according to the same rules as followed for filling of atomic orbitals.

However, the order for filling is not the same for all molecules or their ions. Bond order is one of the most important parameters to compare the strength of bonds.

Which of the following pair is expected to have the same bond order?

A
$\mathrm{O}_2, \mathrm{~N}_2$
B
$\mathrm{O}_2^{+}, \mathrm{N}_2^{-}$
C
  $\mathrm{O}_2^{-}, \mathrm{N}_2^{+}$
D
$\mathrm{O}_2^{-}, \mathrm{N}_2^{-}$
68
MCQ (Single Correct Answer)

Molecular orbitals are formed by the overlap of atomic orbitals. Two atomic orbitals combine to form two molecular orbitals called bonding molecular orbital (BMO) and anti-bonding molecular orbital (ABMO). Energy of anti-bonding orbital is raised above the parent atomic orbitals that have combined and the energy of the bonding orbital is lowered than the parent atomic orbitals.

Energies of various molecular orbitals for elements hydrogen to nitrogen increase in the order

$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\sigma 2 p_z<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$ and

For oxygen and fluorine order of energy of molecular orbitals is given below

$$\sigma 1 s<\sigma^* 1 s<\sigma 2 s<\sigma^* 2 s<\sigma p_z<\left(\pi 2 p_x \approx \pi 2 p_y\right)<\left(\pi^* 2 p_x \approx \pi^* 2 p_y\right)<\sigma^* 2 p_z$$

Different atomic orbitals of one atom combine with those atomic orbitals of the second atom which have comparable energies and proper orientation.

Further, if the overlapping is head on, the molecular orbital is called 'sigma', ( $\sigma$ ) and if the overlap is lateral, the molecular orbital is called 'pi', $(\pi)$. The molecular orbitals are filled with electrons according to the same rules as followed for filling of atomic orbitals.

However, the order for filling is not the same for all molecules or their ions. Bond order is one of the most important parameters to compare the strength of bonds.

In which of the following molecules, $\sigma 2 p_z$ molecular orbital is filled after $\pi 2 p_x$ and $\pi 2 p_y$ molecular orbitals?

A
$\mathrm{O}_2$
B
$\mathrm{N}_2$
C
$\mathrm{Ne}_2$
D
$\mathrm{F}_2$