d & f–Block Elements
d-Block Elements
y The d-block of the periodic table contains
the elements of the group 3-12 in which the Definitions
d-orbitals are progressively filled in each of
Elements in which last electron
the four long periods.
enters into d-subshell are
y In these elements, the last electron enters (n
known as d-block elements.
– 1) d-subshell (d-orbitals of the penultimate
orbit), i.e., (n – 1) d-subshell is gradually filled
up. The configuration varies from (n – 1)d1ns2
to (n – 1)d10ns2.
y These are present between s-block and
p-block elements. The properties of these
elements are intermediate between the Concept Ladder
properties of s-block and p-block elements.
y Forty elements belong to d-block. Fourth, Vertical relationship is due
fifth, sixth and seventh periods consists of to similar outer electronic
ten elements each. configuration while
y There are mainly three series of the transition horizontal relationship is
metals. due to combined effect of s
(i) 3d series (Sc — Zn) and zeff.
(ii) 4d series (Y — Cd)
(iii) 5d series (La — Hg)
(iv) 6d series (Ac — Uub)
d & f–Block Elements
1.
,d & f–Block Elements
2.
,Transition Elements :
y They are often called “Transition elements” Concept Ladder
because their position in the periodic table
between s-block and p-block elements. In d-block, 12th group
y Typically, the transition elements have an elements like Zn, Cd and Hg
incompletely filled d-level. Since 12th group do not have partially filled
has d10 configuration and are not considered (n – 1) d—subshells either
as transition elements but they are d-block in its atomic or ionic state.
elements. That is why these elements
y d-block elements show horizontal as well as not termed as transition
vertical relationship. elements.
y Zn, Cd and Hg are generally not regarded as
transition elements.
Ex: Zn, Cd and Hg Previous Year’s Question
Zn 3d104s2
Cd 4d105s2
A transition element X has
Hg 5d106s2
a configuration [Ar]3d4 in its
y So out of 40 d-block elements there are 37
+3-oxidation state. Its atomic
transition elements.
d & f–Block Elements
number is [AIPMT]
y All transition elements are d-block elements
(1) 25 (2) 26
but all d-block elements are not transition
(3) 22 (4) 19
elements.
3.
, Q.1 Why chromium is a transition element but zinc is not ?
A.1 Transitions elements have incomplete d-orbitals chromium has [Ar]4s13d5
i.e. Partially filled d-orbitals but in case zinc having [Ar]4s23d10 i.e. fully filled
d-orbitals.
Hence, chromium is a transition elements whereas zinc is not.
Electronic Configuration :
General E.C. of d-block (n–1)d1-10ns0-2 Concept Ladder
For 3d series 3d1-104s1-2
For 4d series 4d1-105s0-2 The d-orbitals of the
For 5d series 5d1-106s1-2 transition element project
For 6d series 6d1-107s1-2 to the periphery of an
y Most of the elements possess two electrons in atom more than the other
the outermost orbital, i.e., ns2. However, some orbitals (s and p). Hence,
of the elements such as Cr, Cu, Nb, Mo, Ru, they are more influenced
Rh, Ag, Pt, Au and Rg have one electron in the by the surrounding as well
outermost orbital, i.e., ns1 while one element as affecting the atoms or
palladium has no electron on ns orbital. molecules surrounding
them.
Q.2 Write the electronic configuration of following species.
(i) Cr (ii) Zn
A.2 (i) Cr – Atomic number (Z = 24)
1s2 2s2 2p6 3s2 3p6 4s1 3d5
(ii) Zn – Atomic number (Z = 30)
1s2 2s2 2p6 3s2 3p6 4s2 3d10
y The irregularities in the observed configuration
of Cr [Ar]3d54s1 instead of [Ar]3d44s2, Cu Rack your Brain
[Ar]3d104s1, Mo [Kr]4d55s1, Pd [Kr]4d105s0, Au
d & f–Block Elements
[Xe]4f145d106s1, Ag [Kr]4d105s1 are explained on Why copper is considered to
the basis of the concept that half-filled and be transition element even
completely filled d-orbitals is relatively more its atom has completely filled
stable than partially filled d-orbitals. d-orbital in its ground state.
4.
d-Block Elements
y The d-block of the periodic table contains
the elements of the group 3-12 in which the Definitions
d-orbitals are progressively filled in each of
Elements in which last electron
the four long periods.
enters into d-subshell are
y In these elements, the last electron enters (n
known as d-block elements.
– 1) d-subshell (d-orbitals of the penultimate
orbit), i.e., (n – 1) d-subshell is gradually filled
up. The configuration varies from (n – 1)d1ns2
to (n – 1)d10ns2.
y These are present between s-block and
p-block elements. The properties of these
elements are intermediate between the Concept Ladder
properties of s-block and p-block elements.
y Forty elements belong to d-block. Fourth, Vertical relationship is due
fifth, sixth and seventh periods consists of to similar outer electronic
ten elements each. configuration while
y There are mainly three series of the transition horizontal relationship is
metals. due to combined effect of s
(i) 3d series (Sc — Zn) and zeff.
(ii) 4d series (Y — Cd)
(iii) 5d series (La — Hg)
(iv) 6d series (Ac — Uub)
d & f–Block Elements
1.
,d & f–Block Elements
2.
,Transition Elements :
y They are often called “Transition elements” Concept Ladder
because their position in the periodic table
between s-block and p-block elements. In d-block, 12th group
y Typically, the transition elements have an elements like Zn, Cd and Hg
incompletely filled d-level. Since 12th group do not have partially filled
has d10 configuration and are not considered (n – 1) d—subshells either
as transition elements but they are d-block in its atomic or ionic state.
elements. That is why these elements
y d-block elements show horizontal as well as not termed as transition
vertical relationship. elements.
y Zn, Cd and Hg are generally not regarded as
transition elements.
Ex: Zn, Cd and Hg Previous Year’s Question
Zn 3d104s2
Cd 4d105s2
A transition element X has
Hg 5d106s2
a configuration [Ar]3d4 in its
y So out of 40 d-block elements there are 37
+3-oxidation state. Its atomic
transition elements.
d & f–Block Elements
number is [AIPMT]
y All transition elements are d-block elements
(1) 25 (2) 26
but all d-block elements are not transition
(3) 22 (4) 19
elements.
3.
, Q.1 Why chromium is a transition element but zinc is not ?
A.1 Transitions elements have incomplete d-orbitals chromium has [Ar]4s13d5
i.e. Partially filled d-orbitals but in case zinc having [Ar]4s23d10 i.e. fully filled
d-orbitals.
Hence, chromium is a transition elements whereas zinc is not.
Electronic Configuration :
General E.C. of d-block (n–1)d1-10ns0-2 Concept Ladder
For 3d series 3d1-104s1-2
For 4d series 4d1-105s0-2 The d-orbitals of the
For 5d series 5d1-106s1-2 transition element project
For 6d series 6d1-107s1-2 to the periphery of an
y Most of the elements possess two electrons in atom more than the other
the outermost orbital, i.e., ns2. However, some orbitals (s and p). Hence,
of the elements such as Cr, Cu, Nb, Mo, Ru, they are more influenced
Rh, Ag, Pt, Au and Rg have one electron in the by the surrounding as well
outermost orbital, i.e., ns1 while one element as affecting the atoms or
palladium has no electron on ns orbital. molecules surrounding
them.
Q.2 Write the electronic configuration of following species.
(i) Cr (ii) Zn
A.2 (i) Cr – Atomic number (Z = 24)
1s2 2s2 2p6 3s2 3p6 4s1 3d5
(ii) Zn – Atomic number (Z = 30)
1s2 2s2 2p6 3s2 3p6 4s2 3d10
y The irregularities in the observed configuration
of Cr [Ar]3d54s1 instead of [Ar]3d44s2, Cu Rack your Brain
[Ar]3d104s1, Mo [Kr]4d55s1, Pd [Kr]4d105s0, Au
d & f–Block Elements
[Xe]4f145d106s1, Ag [Kr]4d105s1 are explained on Why copper is considered to
the basis of the concept that half-filled and be transition element even
completely filled d-orbitals is relatively more its atom has completely filled
stable than partially filled d-orbitals. d-orbital in its ground state.
4.
