Hybridization - 4.3

Q1: What are the two main theories that describe quantum mechanics in chemical bonding?

Valence Bond Theory (VBT) & Molecular Orbital Theory (MOT)

Valence Bond Theory (VBT):

• covalent bonds form when the atomic orbitals

  of two atoms overlap to share a common region in space and a pair of

  electrons

• Electrons are shared by each atom

Molecular Orbital Theory (MOT):

• When atomic orbitals overlap, they form new orbitals called molecular orbitals.

• Electrons are delocalized (spread out) across the molecule.

• A quantum mechanical theory is applied

Q: What are the three main concepts of Molecular Orbital Theory?

A:

1. The region of orbital overlap has a maximum capacity of two electrons, and the electrons must have opposite spins.

2. There should be maximum overlap of orbitals. The greater the orbital overlap, the stronger and more stable the bond. The extent of orbital overlap depends on the shapes and directions of the orbitals that are involved in bonding.

3. Hybridization is used to help determine the atomic shape

Q5: What is a Molecular Orbital Diagram used for?

It shows how atomic orbitals combine to form bonding and antibonding molecular orbitals.

• Example practice molecules: Hydrogen Fluoride (HF) and Fluorine Gas (F₂).

What is a Hybrid Orbital?

• an orbital that is formed by a combination of two or more orbitals in the valence shell of an atom

  • Essentially, we can transfer an electron from an orbital into another orbital (of higher level) within the same atom

E.g. CH4

C= 2s2, 2p2

• We can transfer the electron from the s orbital into the p orbital to make it stable

It will now become sp3.

Q7: What are the different types of hybridization based on the number of bonds?

Bonds to Central Atom	Type of Hybridization

5 bonds

sp³d

4 bonds

sp³

3 bonds

sp²

2 bonds

sp

1 bond

s

Q8: What types of bonds are formed based on sigma (σ) and pi (π) bonds?

A:

• Single bond: 1 sigma (σ)

• Double bond: 1 sigma (σ) + 1 pi (π)

• Triple bond: 1 sigma (σ) + 2 pi (π)

Q9: What is the hybridization for double and triple bonds?

A:

• Double bond: sp² hybridization (σ + π)

• Triple bond: sp hybridization (σ + 2π)

Q10: What are Allotropes?

Allotropes: one of two or more

structurally different forms of the same

element having different physical

properties

Example of allotropes

E.g., Pure carbon can be hard like a

diamond or slippery as used in pencils

Why allotropes?

The carbon can bond in different

structures to each other