What is the coordination number for each of the following complexes or compounds? [Co (NH3) 4 (H2O) 2]3 + [Cr (EDTA) ] - [Pt (NH3) 4]2 + Na[Au (Cl) 2]?

[Co (NH₃) ₄ (H₂O) ₂]³⁺: coordination number = 6.

[Cr (EDTA) ]⁻: coordination number = 6.

[Pt (NH₃) ₄]²⁺: coordination number = 4.

Na[Au (Cl) ₂]: coordination number = 2.

Explanation:

[Co (NH₃) ₄ (H₂O) ₂]³⁺:

In this complex, Co is bonded with 4 molecules of NH₃ (with 4 coordinate bonds, one bond for each molecule) and 2 molecules of H₂O (with 2 coordinate bonds, one bond for each molecule) forming the complex with 6 coordinate bonds.

∴ coordination number = 6.

[Cr (EDTA) ]⁻:

In this complex, Cr is bonded with 1 molecules of EDTA (with 6 coordinate bonds, 4 O atoms and 2 N atoms in EDTA molecule).

∴ coordination number = 6.

[Pt (NH₃) ₄]²⁺:

In this complex, Pt is bonded with 4 molecules of NH₃ (with 4 coordinate bonds, one bond for each molecule).

coordination number = 4.

Na[Au (Cl) ₂]:

In this complex, Au is bonded with 2 atoms of Cl (with 2 coordinate bonds, one bond for each atom).

coordination number = 2.