What is Spectrochemical Series? Write is the Difference Between a Weak field Ligand and a Strong Field Ligand

Answer: 

Spectrochemical series is a list of ligands ranked according to their strength or a list of metal ions ranked according to various properties. The series is placed in a descending order according to the splitting value of ligands.

Strong field ligand:

• High splitting of crystal fields.
• Low spin molecules.
• Mostly has N, C and P as sites of giving out electrons/ donor sites.
• C.F.S.E > pairing energy.

Weak field ligand:

• Less splitting of crystal fields.
• High spin molecules.
• Mostly has X, O and S as donor sites.
• C.F.S.E < pairing energy.