D and F Block

The d- and fBlock Elements
d- block elements
d – block elements
• The d-block of the periodic table contains the
elements of the groups 3-12 in which the d orbitals
are progressively filled in each of the four long
periods.
• Those elements in which last electron enters in d-

orbital are called d - block elements .
• These are also known as transition elements

Position in the Periodic Table
• position between s– and p– block elements
• Electronic Configurations
• (n-1)d 1–10ns 1–2
– The (n–1) stands for the inner d orbitals
• The electronic configurations of Cr and Cu in the 3d
series:
Consider the case of Cr, which has 3d 5 4s 1 instead
of 3d 4 4s 2 ; the energy gap between the two sets (3d
and 4s) of orbitals is small enough to prevent electron
entering the 3d orbitals.
Similarly in case of Cu, the configuration is 3d 104s 1
and not 3d 9 4s 2
• Why are Zn, Cd and Hg not considered as
transition elements ?
Zn (3d10) , Cd (4d10) and Hg (5d10) have
fully filled d- orbital . So these are not
considered as transition elements.
• What are transition elements ?
Those elements which have partially filled
d- orbital in their ground state as well as most
common oxidation state
Atomic radii of 3d series
• As we move from left to right in 3-d series, atomic radii
of 3-d elements first decreases than remains same and
in the end of the series atomic radii increases.
• Reason :- Initially atomic radii decreases due to the

increase in nuclear charge. In the middle of the series,
the increased nuclear charge and screening effect
balance each other and atomic radii become almost
constant. Towards the end of the series , atomic
Magnetic properties
• Most of d- block elements are paramagnetic in

nature due to the presence of unpaired
electron while Zn (3d10 ), Cd (4d10 ) and Hg
(5d10 ) are diamagnetic due to the presence of
paired electron.
magnetic character of Fe 2+
• Fe – (Ar)18 3d6 4s2

26
• Fe2+ – (Ar)18 3d6 4s0
Fe2+ is paramagnetic due to the presence of unpaired

electrons.
Magnetic moment (μ) = √ n(n+2) BM
= √ 4(4+2) BM = √26 BM
Catalytic Behaviour
Positive catalyst Negative catalyst
which increases the speed of which decreases the speed of
chemical reaction chemical reaction
Alloy formation
• The transition metals readily form alloys
because of their similar radii .The alloys so
formed are hard and have often high melting
point .
Formation of Interstitial compounds
• Transition metals are in size and have lots of interstitial
sites . The atoms of other elements having small size,
such as H , C , N are trapped in the interstitial sites of
crystal lattice of transition elements resulting in the
formation of interstitial compounds.
Properties:-
• High melting point than those of pure metals.

• These are very hard, chemically inert.
• Retain metallic conductivity.
Formation of complex compounds
• Transition metal form a large no . df complex

compounds .Due to smaller size, High nuclear
charge and also have vacant d - orbtal in which
they can accept lone pair of electrons from
ligands.
FORMATION OF COLOURED IONS
• The transition metal display a
variety of colour in aqueous
solution because of the presence
of unpaired electrons. These
unpaired electrons absorb light
from visible region and can
undergo d-d transition . The
colour of the compound absorbed
is complementary to the colour of
radiation absorbed.
Zn2+ is colourless while Fe2+coloured?
• Zn2+ → (Ar)18 3d10 4s0

Zn2+ have no unpaired electrons, so no d-d
transition is possible, that's why Zn2+ is
colourless.
• Fe2+ → (Ar)18 3d8 4S0

Fe2+ have unpaired e lectrons. So d-d transition is
possible. That's why Fe2+ is coloured.
Oxidation State
• Transition elements show a variety of oxidation
state in their compounds because of very little
difference in energies of ns and (n-1) d
Stability of Higher Oxidation State
The higher oxidation state of an element is exhibited

in its compound with fluorine and oxygen because
these are highly electronegative and strong oxidising
agent.
"The ability of oxygen to stabilize these higher

Oxidation State exceeds that of fluorine due to its
ability of making double bond.”
Ionization Enthalpy
As we move from left to right in any transition

series, the ionisation enthalpy increases
gradually due to increase in nuclear charge.
Standard Electrode Potential
• Electrode potential depends upon the balance
between value of hydration enthalpy and sum of
values of ionisation enthalpy and enthalpy of
atomization.
Metallic Character
• Nearly all the transition elements display typical
metallic properties such as high tensile strength,
ductility, malleability, high thermal and electrical
conductivity and metallic lustre.
• With the exceptions of Zn, Cd, Hg and Mn, they have

one or more typical metallic structures at normal
temperatures.
• Transition metals are good metals and generally have
high melting point because of strong metallic bond
due to unpaired electrons.
• The metals of the second and third series have greater
enthalpies of atomisation than the corresponding
elements of the first series; this is an important factor in
accounting for the occurrence of much more frequent
metal – metal bonding in compounds of the heavy
transition metals.

D and F Block

Uploaded by

Copyright:

Available Formats

D and F Block

Uploaded by

Document Information

Original Description:

Original Title

Copyright

Available Formats

Share this document

Share or Embed Document

Sharing Options

Did you find this document useful?

Is this content inappropriate?

Copyright:

Available Formats

D and F Block

Uploaded by

Copyright:

Available Formats

The d- and fBlock Elements

• Those elements in which last electron enters in d-

• These are also known as transition elements

• position between s– and p– block elements

• Reason :- Initially atomic radii decreases due to the

• Most of d- block elements are paramagnetic in

• Fe – (Ar)18 3d6 4s2

• Fe2+ – (Ar)18 3d6 4s0

Fe2+ is paramagnetic due to the presence of unpaired

• High melting point than those of pure metals.

• Transition metal form a large no . df complex

• Zn2+ → (Ar)18 3d10 4s0

• Fe2+ → (Ar)18 3d8 4S0

The higher oxidation state of an element is exhibited

"The ability of oxygen to stabilize these higher

As we move from left to right in any transition

• With the exceptions of Zn, Cd, Hg and Mn, they have

You might also like