Question

What is the coordination number?

• A. The number of ligands attached to the central metal atom or ion.
• B. The number of central atoms.
• C. The total number of bonds in the compound.
• D. The total number of covalent bonds in the compound.
• E. The total number of hydrogens attached to the central metal atom or ion.

Answer 1

Answer: (A)

The number of ligands attached to the central metal atom or ion.

The coordination number is the number of ligands attached to the central metal atom or ion.

For example, tetra carbonyl nickel $Ni(CO{)}_4$ has a coordination number of 4 as 4 CO ligands are attached to Ni atom.