CBSE Class 12 Chemistry Coordination Compound Notes and Questions. Based on CBSE and NCERT guidelines. The students should practice these Questions to gain perfection which will help him to get more marks in CBSE examination. Based on CBSE and NCERT guidelines. The preparation should be in a manner which helps the students to concentrate more in areas which carry more marks.
The compounds which contain dative bonds between metal atom and surrounding species is called co-ordination compounds .The branch of inorganic chemistry which deals with hte study of preparation properties of coordination compound is called co-ordination chemistry.
POINTS TO REMEMBER:
Coordination compounds are compounds in which a central metal atom or ion is linked to a
number of ions or neutral molecules by coordinate bonds or which contain complex ions. Examples- K4[Fe(CN)6]; [ Cu(NH3)4]SO4; Ni(CO)4
2.The main postulates of Werner’s theory of coordination compounds
i) In coordination compounds metals show two types of linkages or valencies- Primary and Secondary.
ii) The primary valencies are ionisable and are satisfied by negative ions.
iii) The secondary valencies are non- ionisable and are satisfied by neutral molecules or negative ions. The secondary valence is equal to the C.N and is fixed for a metal.
iv) The ions or groups bound by secondary linkages to the metal have characteristic spatial arrangements corresponding to different coordination nos.
3.Difference between a double salt and a complex
Both double salts as well as complexes are formed by the combination of two or more stable compounds in stoichiometric ratio. However, double salts such as carnallite, KCl.MgCl2.6H2O, Mohr‘s salt, FeSO4.(NH4)2SO4.6H2O, potash alum, KAl(SO4)2.12H2O, etc. dissociate into simple ions completely when dissolved in water. However, complex ions such as [Fe(CN)6]4– of K4[Fe(CN)6], do not dissociate into Fe2+ and CN– ions.
(i) Coordination entity: It constitutes the central metal ion or atom bonded to a fixed number of ions or molecules represented within a square bracket.
(ii) Central atom/ ion: In a coordination entity, the atom/ion to which a fixed number of ions/groups are bound in a definite geometrical arrangement around it, is called the central atom or ion.
iii) Ligands: The neutral or negative ions bound to the central metal or ion in the coordination entity. These donate a pair/s of electrons to the central metal atom /ion. Ligands may be classified as-
a) Monodentate/Unidentate: Ligands bound to the central metal atom/ion through a single donor atom. Ex- Cl- ; H2O ; NH3 ; NO2-.
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