Friday, August 17, 2012

XII year Notes of Periodic Table


 Quality Education At Every level

 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 5d4f1 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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