Question

The co-ordination number of a central metal atom in a complex is determined by ___________.

• A. the number of ligands around a metal ion bonded by sigma bonds
• B. the number of ligands around a metal ion bonded by pi-bonds
• C. the number of ligands around a metal ion bonded by sigma and pi-bonds both
• D. the number of only anionic ligands bonded to the metal ion

Answer 1

The correct option is A the number of ligands around a metal ion bonded by sigma bonds

The co-ordination number of a central metal atom in a complex is determined by the number of ligands around a metal ion bonded by sigma bonds. It is also define as the number of atoms, ions, or molecules that a central atom or ion holds as its nearest neighbors in a complex. For example, in $Ni(CO{)}_4$, four carbonyl ligands are bonded to Ni atom. Hence, the coordination number of Ni in $Ni(CO{)}_4$ is four.