The document discusses the classification and properties of elements according to their electronic configurations. It describes the four blocks of elements - s-block, p-block, d-block, and f-block. S-block elements have their outermost electrons in the s orbital and include Groups 1 and 2 metals. P-block elements have their outermost electrons in p orbitals and include Groups 13-18. D-block elements have electrons in d orbitals and are also known as transition metals. F-block elements have electrons in f orbitals. Transition metals are defined as elements that form stable ions with partially filled d orbitals. Their key properties include variable oxidation states, colored compounds, ability to form complexes, role as catalyst

1. Chemistry 1st
paper
Chapter-3
Periodic properties and chemical bond
Topic: s,p,d and f-block elements
Elements are classified into four groups according to their electronic configuration.
Those are as follows:
(1) s-block elements
(2) p-block elements
(3) d-block elements
(4) f-block elements
s-block element: The elements of which last electron enter into s orbital are called
s -block element. Their outer most shell is ns1
and ns2
.The s-block elements consist
Gr-1(alkali metal) and Gr-2(alkaline earth metal). There are 14 elements present in s -
block.
 The s-block elements are the metals in Group 1(IA) and 2(IIA) of the Periodic
Table.
 Group IA - alkali metals : Li, Na, K, Rb, Cs, Fr
 Group IIA - alkaline earth metals: Be, Mg, Ca, Sr, Ba, Ra
 Why Ca is called alkaline earth metal?
Ans. The element which can produce alkali in water is called alkaline metal. Ca
produces Ca(OH)2 with water so that it is alkaline. As Ca found with soil mostly
thus it is called alkaline earth metal.
p-block element: The elements of which last electron enter into p orbital are called p -
block element. Their outer most shell is ns2
np1-6
.The p-block elements consist Gr-13 to
Gr-18. There are 32 elements present in p -block. p block elements consisting all types
of typical elements like metal, non metal, metalloid and inert gases.
Gr -13(ns2
np1
) Gr -14(ns2
np2
) Gr- 15(ns2
np3
) Gr -16 (ns2
np4
) Gr -17(ns2
np5
) Gr -18(ns2
np6
)
B(5) C(6) N(7) O(8) F(9) Ne(10)
Al(13) Si(14) P(15) S(16) Cl(17) Ar(18)
Ga(31) Ge(32) As(33) Se(34) Br(35) Kr(36)
In(49) Sn(50) Sb(51) Te(52) I(53) Xe(54)
Tl(81) Pb(82) Bi (83) Po(84) At(85) Rn(86)
d-block element: The elements of which last electron enter into d orbital are called d -
block element. Their outer most shell is ns2
(n-1)d1-10
.The d-block elements consist Gr-3
to Gr-12. There are 41 elements present in
d -block. d- block elements are known as transition elements.
Jakir Sir
01712653341

2. Transition element: The element of which has minimum one stable ion consisting
partially filled d orbital is called transition element.
 Electronic configuration of 3d series of d-block elements:
Elements
Electronic
configuration/
Valence shell
Sc [Ar] 3d1
4s2
Ti [Ar] 3d2
4s2
V [Ar] 3d3
4s2
Cr [Ar] 3d5
4s1
Mn [Ar] 3d5
4s2
Fe [Ar] 3d6
4s2
Co [Ar] 3d7
4s2
Ni [Ar] 3d8
4s2
Cu [Ar] 3d10
4s1
Zn [Ar] 3d10
4s2
 Why not Sc and Zn aren’t transition elements? OR all d-block elements are
not transition but all transition elements are d-block.
Ans: The element of which has minimum one stable ion consisting partially filled d
orbital is called transition element.
Sc forms Sc3+
and Zn forms Zn2+
ion only. Their electronic configurations are as
following:
10626222
626223
333221:)30(
33221:)21(
dPSPSSZn
PSPSSSc


As there is no d orbital in case of Sc3+
and fulfilled d orbital in case of Zn2+
so
that
Sc and Zn aren’t transition elements.
Although they are d block elements so that we can say all d-block elements are
not transition but all transition elements are d-block.
 Characteristics of transition elements:
 Transition elements show variable oxidation number.
 Transition elements produce colored ion/compound.
 Transition elements form complex ion/compound
 Transition elements act as catalyst
 Transition elements are paramagnetic

3.  Explanation of the characteristics of transition elements:
 Transition elements show variable oxidation number.
The element of which has minimum one stable ion consisting partially filled d
orbital is called transition element. As there are vacant d orbitals present in
transition element so they can transfer electron from d orbital to d orbital. At the
same time electron can move between 3d and 4s. In this way transition elements
can produce different number of unpaired electron which help them to produce
different ions. The produces ions are stable also. This is why transition elements
show variable oxidation number.
Elements Oxidation numbers
Cr +3, +6,
Fe +2, +3
Cu +1, +2
 Transition elements produce colored ion/compound.
The element of which has minimum one stable ion consisting partially filled d
orbital is called transition element. As there are vacant d orbitals present in
transition element so they can transfer electron from d orbital to d orbital. At
normal state d orbitals carried equal energy this is called degenerate state. When
transition elements produce ion then splitting of d orbitals occurred by the
electrostatic force between metal ion and ligand. This is called non degenerate
state. In this state d orbitals divided into two energy state. Electron moves lower
energy state to higher by absorbing visible light and radiates complementary color
when moves lower energy state from higher energy state. Thus transition
elements produce colored ion/compound. For example
Cu2+
: ∆E
Degenerate state
Non degenerate state
 Transition elements form complex ion/compound:
Complex compound: The compound in which transition metal or metal ion
accepts lone pair electron from other ions, molecules which is called ligand is
known as complex compound.

4. Ligand: The chemical substance which can supply lone pair electron in the
coordinate bonding with a transition metal.
Complex compound Complex ion Ligand
Coordination
number
[Cu(NH3)4]SO4 [Cu(NH3)4]2+
NH3 4
[Co(NH3)6]Cl3 [Co(NH3)6]3+
NH3 6
K4[Fe(CN)6] [Fe(CN)6]4-
CN-
6
 Transition elements act as catalyst
Transition elements and some of their compounds are commonly used as catalysts in
chemical process. The transition elements as catalyst , may form unstable
intermediate compounds in some cases, and in other cases they provide a suitable
surface area where gases are absorbed.
e.g; Pd, Pt, Ni, Ti, V, V2O5, Fe2O3, are used.
 Transition elements are paramagnetic :
Paramagnetic is such kind of substance which weakly attracted by magnetic pole
create magnetism but doesn’t retain the magnetism permanently. Many transition
elements are paramagnetic as they are attracted into a magnetic field. Para
magnetism is due to presence of unpaired electron spins in the ions and atoms.
Para magnetism is due to the presence of unpaired electron spins in the ions and
atoms. On the other hand substances possess paired electrons are diamagnetic
like Zn.