d and f block elements
D Block (Transition Metals):
- Found in groups 3 to 12.
- Exhibit metallic properties.
- Variable oxidation states.
- Examples: Iron, Copper, Zinc.
- Used in construction, electronics, and catalysis.
F Block (Inner Transition Metals):
- Located in periods 6 and 7.
- Include lanthanides and actinides.
- Examples: Cerium, Uranium.
- Primarily used in nuclear technology and lighting.
- Large atomic and ionic radii, high densities.
- Conclusion:
D and F block elements are crucial in various industries due to their unique properties and applications, from catalysis to nuclear technology.
Here's a comprehensive set of notes on d and f block elements:
download chapter no: 2 “d” AND “f” BLOCK ELEMENTS
We must keep in minds that full filled shells and full filled sub-shells are
always more stable. The half filled shells and half filled sub-shells are next in
stability. Partially filled (less than half filled) and more than half filled shells and sub-
shells are less stable. As in transition elements there is a small energy gap between 4s
and 3d sub-shell so electron from 4s can be promoted easily to 3d for the sake of
stable configuration.
Chromium has two electrons in the 4s sub-shell and four electrons in the 3d
sub-shell. As “s” sub-shell is full filled but d sub-shell is less than half filled so the
resultant stability of both the sub-shells is less. If one electron is promoted from 4s to
3d then both will become half filled and their resultant stability will be more. So the
electronic configuration of Chromium must be written as 4s1
, 3d5
instead of 4s2
, 3d4
.
In case of Copper, there are 2 electrons in the 4s and 9 electrons in the 3d. 4s is
full filled but 3d is not. If an electron is promoted from the 4s to the 3d then 4s will
become half filled and 3d full filled and now their resultant stability will be more. So
the electronic configuration of Copper must be written as 4s1
, 3d10 instead of 4s2
, 3d9
Transition elements are larger in size and having loosely held electrons which
can easily form electron sea in the inter-atomic spaces in transition metal lattices.
Transition elements absorb the reactants provide them their free electrons and convert
them into atomic (nascent) form. These reactants in the atomic form the react quickly
and form products. Transition elements are good electron losers also electrons pair
acceptors and absorbers forming intermediates and accelerate the rate of a chemical
reaction. Therefore these are used as catalysts. The mechanism of iron catalyst in
Haber process and in the case of oxidation by peroxodisulphate has been given in the
theory in detail.
As transition metals has vacant d and f orbitals, these have high charge density
and are capable of accepting lone pair of electrons from the ligands so these can play
the role of central metal atoms or central metal ions and form complexes or
coordination compounds.
In [Cr(H2O)6]
+3 the whole charge on the complex ion is +3. Charge on the
coordination sphere is sum of the charges of the central metal atom and ligands. As
the ligand water is neutral has zero oxidation state so the +3 charge is due to the
Chromium. Thus the oxidation state of Chromium in the above specie is +3.