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Class :XII year Chapter
#01
Prepared
by:
Lecturer S.Fayyaz Hussain
Email address: fayyazhussain396@gmail.com
PERIODIC TABLE
Classification of Elements:
The aim of classification of element
to group together similar element and to separate dissimilar ones.
Berzelius
Classification:
He
classified elements into metals and non-metals on the basis of valance electrochemical
behavior acidic or basic properties. But the system was failed. Because many
elements such as Arsenic and antimony behave like metalloids. Metalloids are
the substances exhibit metallic and non-metallic properties.
Dobereiner’s
Triad:
J . W . Dobereiner (1829) classified man
chemically similar element in the group of three known as Triad, such
that the atomic mass of the middle element was very close to the mean of the
other two.
Element
Atomic Element Atomic
Element Atomic MEAN
Mass Mass Mass
1- Lithium
7 Sodium 23 Potassium 39 (7+39)/2=23 2-
Phosphorus 31
Arsenic 75 Antimony 120
(31+125)/2=75.5
3- Sulphur 32 Selenium 79
Tellurium 128
(32+128)/2=80
4- Chlorine 35.5 Bromine 80
Iodine 127 (35.5+127)/2=81.25
5- Calcium 40 Strontium 87.5
Barium 137 (40+137)/2=87.5
This law gives the idea to classified the elements
of similar properties into same group. But all the elements did not fall into
Triads.
NEW
LAND’S OF OCTAVES:-
J . A . R Newland (1864) arranged the
elements in the order of their increasing atomic masses. He observed that every
eighth element is proceeding it.
Li Be B C N O F
7 9 11 12 14 16 19
Na Mg Al Si P S Cl
23 24 27 28 31 32 35.5
This law is failed due to
application is limited to a few elements.
LOTHAR
MEYER’S Periodic Law:
In 1869 Lothar Meyr proposed that atomic
volumes
of elements are periodic functions of their atomic masses:
When
he plotted these atomic volume against the corresponding atomic masses, a curve
taking the form of sharp peaks and broad minima was obtained.
Figure#1
The generalisation can be
made from the shape of the curve is as follows:
(a) Gaseous , volatile and readily fussed element are
locate on the ascending portion of the curve or at the peaks.
(b)
Elements with high melting
are found on the descending portion of the curve and at the broad minima.
(c)
Chemically similar
elements occupy similar positions on Rubidium, and bromine and iodine occurs on
the ascending portions. Immediately followed by noble element
(Neon,
Argon, Krypton and Xenon)
MENDELEEV’S Periodic Law:
In 1869 Mendeleev’s first published
the periodic system of element on the
basis of periodic law. According to this law physical and chemical
properties of elements are functions of their atomic masses”.
“The properties of elements are periodic functions of their atomic masses”
He arranged the 63 known elements in the periodic
table horizontally in the order of the their similarities in properties. The horizontal
rows are called periods and verticals columns groups.
Figure#2
Advantages:
(1)
Mendeleev’s
excluded certain elements and assigned them a separate position.
(2)
Predicted
the existence of some undiscovered elements
(3)
Left
gaps for the then undiscovered elements.
(4)
The
properties of the elements vary gradually and get repeated at intervals
2.8.8.18.18.and 32 elements respectively.
Dis Advantages :
(1) Position
of hydrogen is not clear. It demands its position on 1st group as
well in 7th group.
(2) Some
chemically dissimilar elements have been placed in the same group for e.g.
alkali metals (Li,Na,K—) of subgroup IA and coinage metals (Cu, Ag, Au, )of sub
group IB are placed in group 1st.
(3) Some
chemically similar elements had been placed differently for e.g., Cu, &
Hg , Ag, and Te and Ba and Pb.
(4) The
order of atomic mass in reverse in some elements (a) Co(58.9) precedes Ni(58.6)
(b) Ar(39.9) precedes K(39.1)
(5) Isotopes
have no place in this periodic table.
“MODERN PERIODIC TABLE”
Modern Periodic law:
Mosley
in 1912 stated that “The physical and chemical properties of the elements are
periodic functions of their atomic number”.
Q. Explain s, p, d, f, classification of the elements.
Ans. According to the valence orbital electronic configuration the
elements are divided into four types.
1 s- block elements
2 p- block elements
3 d- block elements
4 f- block elements
S- block elements:
Element in which the last
electron enters the
s- block elements. This
block contains the element having electronic configuration of ns1
and ns2 are divided into two group IA & II A respectively.
The element of IA group
having electronic configuration ns1 also called alkali metals.
The element of II A group
having electronic configuration ns2 are also called alkali
earth metals s- block elements are placed at the left corner of the periodic
table.
p- block elements:
Elements in which p-orbital are being
progressively filled or element in which the differentiating electron enters
the p- orbital are called p- block. The electronic configuration of this block elements vary from ns2 np1
(group III A ) to ns2 np6 (group VIII A) except the helium
having s2 configuration p- block elements are placed at right corner
of the periodic table.
d- block elements:
Elements
in which the last electron progressively enters the d- block elements are known
as d- block elements. Their two outermost shells are incomplete. The
penultimate shell (inner to the outermost) (n-1) d gets filled from 1 to 10.
The elements having electronic configuration ns2 (n-1)d. these
elements are placed in between s- and p- block. They are further classified
into four transition series corresponding to the filling of 3d, 4d, 5d, and 6d orbital
of (n-1)th shell.
(a)
3d series :-
This series has ten elements 21Sc
to 30Zn. In these element extra electron the 3d orbital .
(b)
4d series :-
This
series has also ten elements 39Y to 48Cd.additional electron
enters the 4d orbital.
(c)
5d series :-
These
are also ten elements 57La, 72Hf to 80Hg.The
extra electron enters 5d- orbital.
(d)
6d series :-
It is in complete series consist of the
elements 89Ac, 104ku to
f-block elements:
Elements on which the last electron enters the
f-block are called f-block elements, the last electron in added in the
anti-penultimate (third from outermost) n-2 shell. These elements have three
incomplete shell. (a)outermost np
orbital (b) d- orbital (c) (n-2) f-orbital. General electronic
configuration of f-block element is ns2
(n-1)d, (n-2) f1to (n-2) f14 f- block elements are
divided into two families.
(a) Lanthanide
or Lathanones:-
(4f-series) These are
14 elements in which 4f-orbital in being
filled.
(b) Actinides
or Actinones:-
(5f-series) These are also 14 elements in which
5f-orbitals I being filled in them, (7s2, 6d1, 5f1)90th
------------ 103lw (7s2, 6d1, 5f14).
The elements of this block is placed at the bottom under the d- & p block
elements.
Figure #3
Type of
elements on the basis of electronic configuration
All the elements are classified into the following
1 Noble gases
2 Normal or representative elements
3 Transition
Noble gases:
The
elements of viii A group having electronic configuration ns2 np6
except helium 1s2. These elements can not react under normal
conditions, that’s why they are called noble gases.
Representative elements:
The elements of s- block & p- block are called representative or normal elements. These
elements tends to acquire ns2 np6 stable in the outermost
orbit by the loss or gain of electron.
(a)S- block
element:
Element in
which the last electron enters the s-
block elements. This block contains the element having electronic
configuration of ns1 and ns2
are divided into two group IA & II A respectively.
The
element of I A group having electronic configuration ns1 also called
alkali metals. The element of II A
group having electronic configuration ns2
are also called alkali earth metals s- block elements are placed at the left corner
of the periodic table.
(b) p- block
elements:
Elements in which p-orbital are being
progressively filled or element in which the differentiating electron enters
the p- orbital are called p- block. The electronic configuration of this block
elements vary from ns2 np1 (group III A) to ns2
np6 (group VIII A) except the helium having s2
configuration p- block elements are placed at right corner of the periodic
table.
Transition
element:
The element of d – and f – block have
properties are midway between those of s – and p – block elements so they are
called transition elements.
(a) Outer Transition element :
The element of d – block are called outer transition
element.
d- block elements:
Elements
in which the last electron progressively enters the d- block elements are known
as d- block elements. Their two outermost shells are incomplete. The penultimate
shell (inner to the outermost) (n-1) d gets filled from 1 to 10. The elements
having electronic configuration ns2 (n-1)d. these elements are
placed in between s- and p- block. They are further classified into four
transition series corresponding to the filling of 3d, 4d, 5d, and 6d orbital of
(n-1)th shell.
(b) Inner Transition :-
The element from of d – block are called inner transition
element.
f-block elements:
Elements on which the last electron enters the f-block are called
f-block elements, the last electron
in added in the anti-penultimate (third from outermost) n-2 shell. These
elements have three incomplete shell. (a)outermost
np orbital (b) d- orbital (c) (n-2) f-orbital. General electronic
configuration of f-block element is ns2 (n-1)d, (n-2) f1to
(n-2) f14 f- block elements are divided into two families.
Explain the period classified on of the periodic Table :
Horizontal
rows are called the periods. The classification of the periods is based on the
maximum principle energy level in electronic configuration.
FIRST
PERIOD:
The element having valance
electron in 1st energy level are placed in the first row. It is the
shortest period of periodic Table for:
SHORT PERIOD :
SECOND
PERIOD:
The elements having valance
electron in second energy level (2sd orbit) are classified as second
period. It contains 2s1 à
2s2 and 2p1 to 2p6. It is also called first
short period. This contains two (2) elements of s- block and six (6) of p –
block.
THIRD
PERIOD:
It is second
short period also eight elements two of s – block and 6 elements of p – block.
The
element of this period having
electronic configuration 3s1
or 3s2 and 3p1 to
3p6
LONG
PERIODS:
There
are two long period in the periodic table
eighteen elements, two (2) of s-block, ten(10) of d-block and six (6)
elements of p- block. the elements of this 4s1 to 4s2 3d1
to 3d10
4p1 to 4p6
(c)FIFTH PERIOD:
It is second long period containing eighteen elements also two(2) of s-block , ten(10) of d-block and six(6)
elements of p-block. the element of this period have electron configuration 5s1
to 5s2 4d1 to 4d10 and 5p1 to 5p6
LONGEST PERIODS
SIXTH
PERIOD:
It is the longest period of the periodic table containing 32 elements
in the adding 14 element of f-block, Lanthanides. The elements of this period
having electronic configuration 6s1 or 6s2 5d1 4f1 to 4f14 5d1 to 5d10 and 6p1
to 6p6
SEVENTH
PERIOD:
It is the incomplete period because some
elements are not discovered yet. The element of this should have electronic
configuration 7s1 or 7s2 6d1 to 6d10 5f1 to 5f14 6d1 to 6d10 and 7p1
to 7p6
GROUP CLASSIFICATION IN THE MODERN
PERIODIC TABLE
The vertical coulombs of the periodic table
in called groups. It base’s classification of the elements in the group in type
of sub-shell and the no of electrons in it. There are two types of groups
1- A types group
2- B types group
A Type
group:- (A class elements):
The elements of s- and p-block are classified
into Eight A type groups.
IA Group:
I A Group is consist of the s-block elements
having electronic configuration ns1. The elements of this group are
also called as Alkali metals. For 3Li = 1s2, 2s1
; 11Na = 1s1, 2s2,2p6,3s1
II A Group:
The elements of s-block having electronic configuration ns2
are classified in II A group. The elements of
II A group are also called as Alkali earth metal.
For e.g. 4Be = 1s2, 2s2
III A Group
:-
The elements of p-block having electronic configuration ns2,
np1 are classified as III A group. It is also known as Boron family.
For e.g. : 5B= 1s1, 2s2,
2p1 13Al
= 1s2, 2s2, 2p6, 3s2, 3p1
IV A Group
:-
IV A consist of the elements of p-block
having electronic configuration ns2, np2. The members of
this group are collectively called as carbon family.
For e.g. : C= 1s2 ,2s2
,2p2
V A Group :-
The
elements having electronic configuration ns2, np3 are
classified in VA group. This group B also known as nitrogen family.
For e.g. 7N, 1s2, 2s2,
2p3 15P
= 1s2, 2s2, 2p6, 3s2, 3p3
VI A Group
:-
Elements of electronic configuration ns2, np4 are
classified in group VI A. This group is also called as oxygen family.
For e.g. 8O, 1s2, 2s2,
2p4 16s
1s2, 2s2, 2p6, 3S2, 3p4
VII A Group
:-
This group in consists of the p-block elements having electronic
configuration ns2, np5. The members of this group are
called halogen .
For e.g. 9F, 1s2, 2s2,
2p5 17Cl
1s2, 2s2, 2p6, 3S2, 3p5
VII A Group
:-
The Elements configuration ns2, np6
are classified in VIII A group. They have filled octet, they do not give or
take electron from other elements there fore they are also called as 0th
(Zeroth group) noble gases or inert gases.
B-Type
Group:-
The elements of d-block are classified into
eight B group.
III B Group
:-
The elements of electronic configuration ns2,
(n-1)d1 are classified in III B, group.
For e.g. 21Sc= 1s2, 2s2,
2p6 3s2 , 3p6,
4s2, 3d1 ;
IV B Group :-
This group is consists of the elements having
electronic configuration ns2(n-1)d2.
For e.g. 22Ti= 1s2, 2s2,
2p6 ,3s2 , 3p6, 4s2, 3d2
;
V B Group :-
The elements of d-block having electronic
configuration ns2(n-1)d3 are classified in VB group.
For e.g. 23V=1s2, 2s2,
2p6 ,3s2 , 3p6, 4s2, 3d3
;
VI B Group :-
ns2(n-1)d4 is the
valence shell configuration of VI B group elements
For e.g. 24Cr,1s2, 2s2,
2p6 ,3s2 , 3p6, 4s2, 3d4
;
VII B Group
:-
The elements of electronic configuration ns2(n-1)d5
are classified into VII B group. For e.g. 25Mn,1s2, 2s2,
2p6 ,3s2 , 3p6, 4s2, 3d5
;
VIII B
Group :-
This
is especial group consist of the elements having three different type of
electron configuration i. e. ns2(n-1)d6, ns2(n-1)d7,
ns2(n-1)d8
For e.g. 27Co,1s2, 2s2,
2p6 ,3s2 , 3p6, 4s2, 3d7
;
28Ni,1s2, 2s2, 2p6
,3s2 , 3p6, 4s2, 3d8
27Fe,1s2, 2s2, 2p6
,3s2 , 3p6, 4s2, 3d6
I B Group:-
The
elements of electronic configuration ns21(n-1)d9
are classified into I B group. It is
Because these in order to get stable shell rearranged their valence shell electron into
relative and exist in the configuration (n-1)d10,ns1
For e.g. 29Ce,1s2,
2s2, 2p6 ,3s2 , 3p6, 4s2,
3d9 ;
but exist in 1s2, 2s2, 2p6
,3s2 , 3p6, 3d10,4s1,
II B Group:-
The elements of electronic configuration ns2(n-1)d10
are placed in II B group. Because filled orbital has lesser energy than filled
s orbital of incomplete orbital.
For e.g. 30Zn,1s2,
2s2, 2p6 ,3s2 , 3p6, 4s2,
3d10 ;
but exist
in 1s2, 2s2,
2p6 ,3s2 , 3p6, 3d10,4s2
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