Chapter 05
Coordination Compound
,Double salt:
Those addition compounds which are stable
in crystalline form and get fully ionized in
aqueous medium are called ‘Double salt’.
Eg: Caranallite, 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.
,Postulates Werner’s Theory
• In coordination compounds metals show two types
of linkages (valences)-primary and secondary.
• The primary valences are normally ionisable and are
satisfied by negative ions.
• The secondary valences are non ionisable. These are
satisfied by neutral molecules or negative ions. The
secondary valence is equal to the coordination
number and is fixed for a metal.
• The ions/groups bound by the secondary linkages to
the metal have characteristic spatial arrangements
corresponding to different coordination numbers.
, Co-ordination Entity
The central metal atom or ion and ligands forms a
co- ordination entity.
Central Metal Atom/Ion
In a co- ordination entity, the metal atom/ion to
which a fixed number of ions/neutral molecules
are attached is called the central atom or ion.
Ligands
The ions or neutral molecules bound to the
central atom/ion in the coordination entity are
called ligands.
Coordination Compound
,Double salt:
Those addition compounds which are stable
in crystalline form and get fully ionized in
aqueous medium are called ‘Double salt’.
Eg: Caranallite, 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.
,Postulates Werner’s Theory
• In coordination compounds metals show two types
of linkages (valences)-primary and secondary.
• The primary valences are normally ionisable and are
satisfied by negative ions.
• The secondary valences are non ionisable. These are
satisfied by neutral molecules or negative ions. The
secondary valence is equal to the coordination
number and is fixed for a metal.
• The ions/groups bound by the secondary linkages to
the metal have characteristic spatial arrangements
corresponding to different coordination numbers.
, Co-ordination Entity
The central metal atom or ion and ligands forms a
co- ordination entity.
Central Metal Atom/Ion
In a co- ordination entity, the metal atom/ion to
which a fixed number of ions/neutral molecules
are attached is called the central atom or ion.
Ligands
The ions or neutral molecules bound to the
central atom/ion in the coordination entity are
called ligands.
