Chemistry XII Content
Transition Metals & Iron
The elements of ‘d’ block of periodic table including elements of Group IB to vii B. And viii are transition metals some important characteristics of transition metals are
· They have general configuration (n-1)d1-10 ns1-2 . They have partially filled valence shell and penultimate shell.
· Transition metals have strong metallic bond, so they are heavy and herd. They have high mpt and bpt.
· They are highly malleable and ductile they have high electrical and thermal conductivity.
· They can absorb large quantity of the gases on their surface and this phenomenon is called occlusion. Because of this property these metals are used as catalyst in gaseous reaction.
· Transition metals show variable oxidation state. For 3d, series, +2 is common O.S.
Eg. Sc → +2 and +3
Cu → +1 and +2
Mn → +2,+3,+4,+5,+6 and +7
MnSO4, Mn2O3, Mno2, Mn2o5, K2Mno4/HMno4
· Transition metal forms colored compounds. The color of compounds is determined by number of unpaired electrons in d-orbital species with some no of unpaired electrons have same color.
Eg. V4 + → Cu4
(Ar)3d1 → (Ar)3d9 both have blue color.
1 Unpaired e+ 1 unpaired e–
· They transition metal and metal ions show paramagnetic nature. The magnetic moment depends upon the number of unpaired electrons in d-orbital.
· Transition metal ion can from complex with ligands. The central metal provides empty orbitals into which ligands donate tone pair of electrons forming co-ordinate co-Volant bond.