Question

The co-ordination number of a metal in co-ordination compound is:

• A. same as primary valency
• B. sum of primary and secondary valences
• C. same as secondary valency
• D. none of the above

Answer 1

Answer: (C)

same as secondary valency

The secondary valency is equal to the coordination number the secondary valency are non ionizable valencies. These are satisfied by neutral molecules or negative ions. For example in $\left[Ni\right(CO{)}_4]$ the coordination number of Ni metal is four and its secondary valency is also four.