NCERT Class 12 Chemistry Solutions Coordination Compounds - NCERT Solutions prepared for CBSE students by the best teachers in Delhi.
Class XII Chemistry
Chapter 9 – Coordination Compounds
Explain the bonding in coordination compounds in terms of Werner’s postulates.
Werner’s postulates explain the bonding in coordination compounds as follows:
(i) A metal exhibits two types of valencies namely, primary and secondary valencies. Primary valencies are satisfied by negative ions while secondary valencies are satisfied by both negative and neutral ions.
(In modern terminology, the primary valency corresponds to the oxidation number of the metal ion, whereas the secondary valency refers to the coordination number of the metalion.
(ii) A metal ion has a definite number of secondary valencies around the central atom. Also, these valencies project in a specific direction in the space assigned to the definite geometry of the coordination compound.
(iii) Primary valencies are usually ionizable, while secondary valencies are non-ionizable.
Explain with two examples each of the following: coordination entity, ligand, coordination number, coordination polyhedron, homoleptic and heteroleptic.
(i) Coordination entity: A coordination entity is an electrically charged radical or species carrying a positive or negative charge. In a coordination entity, the central atom or ion is surrounded by a suitable number of neutral molecules or negative ions ( called ligands).
(ii) Ligands: The neutral molecules or negatively charged ions that surround the metal atom in a coordination entity or a coordinal complex are known as ligands.
(iii) Coordination number: The total number of ligands (either neutral molecules or negative ions) that get attached to the central metal atom in the coordination sphere is called the coordination number of the central metal atom. It is also referred to as its ligancy.
Using IUPAC norms write the formulas for the following:
(ii) Potassium tetrachloridopalladate(II)
(iv) Potassium tetracyanonickelate(II)
(vi) Hexaamminecobalt(III) sulphate
(vii) Potassium tri(oxalato)chromate(III)
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