Question

Distinguish between a monodentate and a bidentate ligand. Give an example of each type. Explain how ligands affect the color of transition-metal ions. What is meant by the statement, "the coordination number of chromium(III) is usually 6?"

Answer 1

Explanation:

Monodentate ligands are the ligands which bind through only one donor atom. Example: chloride ion.

Monodentate ligands are the ligands which bind through two donor atom. Example: ethylenediamine.

When ligands bond with transition metal ion, repulsion between electrons in ligands and electrons in d orbitals of metal ion takes place which raises energy of d orbitals which causes the light to fall in the visible region.

Coordination number is number of donor atoms attached to central ion in a coordination complex. Coordination number of the chromium(III) is usually 6 means that usually chromium(III) bond to 6 ligands and form an octahedral complex.