Name: Nomenclature of Coordination Compounds - I
Uploaded: 2019-07-19
Duration: 7 min 4 s
Description: All the chemical compounds are assigned a name, which is done according to a specific rule. How are coordination compounds named? Let’s watch the video to fi...

Question

Define ligand, coordination number and complex ion. Give one example in each case.

Accepted Answer

(i) Coordination entity(complex):
It is the radical or species that have a positive or negative charge. The central atom or ion is surrounded by a number of neutral molecules or negative ions (called ligands). For example:
${[N i {(N H_{3})}_{6}]}^{2 +}, {[F e {(C N)}_{6}]}^{4 +} =$ cationic complex
${[P t C l_{4}]}^{2 -}, {[A g {(C N)}_{2}]}^{-} =$ anionic complex
$[N i {(C O)}_{4}], [C o {(N H_{3})}_{4} C l_{2}] =$ neutral complex.

(ii) Ligands
The neutral molecules or negatively charged ions that surround the metal atom in a coordination entity or a coordinate complex are known as ligands. They donate a lone pair of electrons. For example, $\ddot{N} H_{3}, H_{2} \ddot{O}, {Cl}^{-} .$

(iii) Coordination number:
The total number of lone pairs donated by ligands (either neutral molecules or negative ions) attached to the central metal atom in the coordination sphere is called the coordination number of the central metal atom.
For example:
(a) $K_{2} [P t C l_{6}],$ six chloride ions attached to $P t$ in the coordinate sphere. So the coordination number of $P t$ is $6 .$
(b) $[N i {(N H_{3})}_{4}] C l_{2},$ the coordination number of the central atom $(N i)$ is $4 .$

Define ligand, coordination number and complex ion. Give one example in each case.

Important Questions on Coordination Compounds

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