2.2G Hybridization

Theoretical and Experimental Structures of Methane

Experimental evidence shows that carbon is tetrahedral

All four C–H bonds are the same

To get methane, carbon would need to have four identical orbitals

Each orbital would hold 1 electron and form one σ-bond

However...

Hybridization

the mixing atomic orbitals to form new hybrid orbitals for bonding.

It involves promoting electrons and merging orbitals in order to get new orbitals, whose shapes match experimental evidence. Hybridization can occur in any covalently bonded molecule.

Types of Hybridization

sp3 orbitals

  • Hybridization gives a model that matches bond geometry

  • sp3 orbitals have 25% s-character and 75% p-character

  • 109.5° apart from one another

sp2 orbitals

Ex: Ethene

π-bonds form via side-to-side overlap of p-orbitals

If a double bond is present, a p-orbital must still remain after hybridization

sp2 look like sp3 but are shorter and wider

sp3 orbitals are oriented 120° apart from one another

sp orbitals

Ex: Ethyne

Shortcut for Determining Hybridization

Steps

  1. Look at atom in molecule

  2. Count the number of electron domains

2 E.D. = sp

3 E.D. = sp2

4 E.D. = sp3

5 E.D. = sp3d

6 E.D. = sp3d2