Hybridization

Lecture notes for lecture 6 of Structure bonding and equillibria

Briefly describe what valence bond theory is

A qualitative picture of bonding,

Based on the assumption that bonds are located between pairs of atoms and that the bonds are formed from the overlap of orbitals on neighbouring atoms

Describe the concept of hybridization

Used in valence bond theory, it describes when orbitals will combine to give birth to hybrid orbitals that are all identical too each other allowing for certain bonding to become possible

Describe the example of sp3 hybridized orbitals in tetrahedral structures

2S orbitals and 2P orbitals are combined to give birth to 4 sp3 hybrids which are each identical and allow for the 4 bonds to come from the 4 corners of a tetrahedron.

Describe the 3d configuration of hybrid orbitals and describe how we see this mathematically

The hybrid orbitals are all configured equally in 3d space

We can see this as an orbital is just a mathematical function and the hybrids are linear combinations of these functions.

Briefly describe constructive interference and how this relates to its combination

When two waves are in phase with each other so they will add to give a greater amplitude

Called a bonding combination as the wave interacts favourably to form a bond

Briefly describe destructive interference

When two waves are not in phase with each other so they will cancel out to give reduced or zero amplitude

Called an antibonding combination as the wave doesn’t interact favourably so is less likely to form a bond

Describe how sp2 hybridization occurs using ethene

The s bond frame work of ethene is made up of the hybridization of two p-orbitals and one s-orbital, these go together to form the c-c sigma bond.

As such, one p-orbital goes unhybridized allowing for it to form the c-c pi bond.

Describe how orbitals hybridise in triple bonded carbon

The carbon only needs to form two bonds, as such hybridization occurs with one s and one p orbital, forming two sp hybridised orbitals.

These are orientated 180 degrees apart from each other forming sigma bonds

Remaining unhybridized p orbitals on each atom overlap sideways to form two pi bonds

What is relation between VSPER and EPG

VSPER indicates the electron pair geometry, and the orbitals have to adopt this mode of hybridization

From linear to octahedral list the electron pair geometry and the hybridisation it indicates

-Linear, sp

-Trigonal Planar, sp2

-Tetrahedral, sp3

-Trigonal bipyramid sp3d

-Octahedralsp3d2

What is the effect hybridisation has on bond length

the more s-character in a given bond the shorter the bond will be. This is because s electrons are held closer to the nucleus.

So in terms of length single > double > triple