Why do we apply Hybridization Schemes?

[SLai_1I]

I am going through past UA worksheets to study and found this question from Matthew's Week 8 Workshop. Does anyone know the answer?

In the ground state, nitrogen has 3 unpaired electrons. Nitrogen normally forms 3
covalent bonds (e.g. NH 3 ). Why do we have to apply a hybridization scheme for nitrogen?

[Claire_Latendresse_1E]

NH3 has a lone pair on the nitrogen, so it has four regions of electron density. It needs four hybrid orbitals, so it assumes an sp3 hybridization.

[Dylan_Nguyen_2C]

I believe we have to apply hybridization schemes to nitrogen because when it forms three covalent bonds, it holds a lone pair along with the three bonded pairs. So instead go having three regions of electron density, there is four and the hybridization that is used is sp3. If hybridization isn't used, then the lone pair is left out and doesn't contribute to shape.