PERIODS AND PERIODIC CLASSIFICATION

 PERIOD

  1. Each period starts with an alkali metal whose outermost electronic configuration is ns¹.
  2. Each period ends with a noble  gas  of outermost electronic configuration ns²np⁶ except He. 
  3. The number of elements in a period is equal to the number of necessary e's to acquire ns²np⁶ configuration in the outermost shell of first element (alkali metal) of the period. First period contains two elements.


ELECTRONIC BASIS OF PERIODIC CLASSIFICATION:-


With a better understanding of the part that the electron plays great role in the properties of the elements .

According to electronic configuration, the elements may be divided into four groups:-

  1. s- block elements,
  2. p-block elements,
  3.  d-block elements.
  4. f-block elements.

S-BLOCK ELEMENTS:-

The elements of the periodic table in which the last electron gets filled in the s-orbital, called s-block elements.


S-orbital can accomodate a maximum of two electrons.


Their general formulae are ns¹ and ns² respectively.
Where n = 1 to 7.


IA group elements = Alkali metals.

IA+ water = behaves like alkali 


IIA = Alkaline earth metals.

 "Alkaline earth metals are those elements which oxides with H2O to form alkali and these are found in the soil  or earth."


The total number of S-block elements are 14.



Fr⁸⁷ and Fr⁸⁸ are radioactive elements whine H and He are gaseous elements.


Cs and Fr are liquid elements belonging to s-block.


Elements of group 1 and group 2 arer called s-block elements.



ELECTRONIC CONFIGURATION OF S-BLOCK ELEMENTS:-

GROUP 1 ARE AS SHOWN IN TABLE BELOW:-

ELECTRONIC CONFIGURATION OF GROUP 1 OF S-BLOCK ELEMENTS.

ELECTRONIC CONFIGURATION OF GROUP 2 OF S BLOCK ELEMENTS:-




ELECTRONIC CONFIGURATION OF GROUP 2 OF S BLOCK ELEMENTS.


P-BLOCK ELEMENTS:-

The elements of periodic table in which the last electron gets filled in the p-orbital, called p-block elements.


A p-orbital can accomodate a maximum of 6 electrons. Therefore, p-block elements are divided into six groups which are IIIA, IVA,VIA,VIIA and zero groups.

General formula = ns²p¹-⁶.
            n = 2to 6.
The zero group elements having general formula ns²p⁶ are inert, because their energy levels are fully filled.


The total number of p-block elements in the periodic ta ke is 30 (excluding He).

There are 9 gaseous elements like (Ne,Ar, Kr,Xe,Rn, F2,Cl2,O2 and N2) belonging to p-block.

Gallium(Ga) and bromine(Br) are liquids.

        BORON FAMILY

           GROUP 13.


ELECTRONIC CONFIGURATION OF BORON FAMILY.


CARBON FAMILY

GROUP 14 ELEMENTS. 





ELECTRONIC CONFIGURATION OF CARBON FAMILY.


       

     NITROGEN GROUP 

GROUP 15

ELECTRONIC CONFIGURATION OF NITROGEN
FAMILY.


         OXYGEN FAMILY

       GROUP -16.

ELECTRONIC CONFIGURATION OF OXYGEN FAMILY.

 

              FLUORINE FAMILY

             GROUP 17.

ELECTRONIC CONFIGURATION OF FLUORINE FAMILY.


         NOBLE GAS.

         GROUP-18.

ELECTRONIC CONFIGURATION OF NOBEL GASES.


d-BLOCK ELEMENTS


The elements of the periodic table in which the last electrons gets filled up in the d- orbital , called d block elements.

The d block elements are placed in the groups name IIIB, IVB  VIIB, VIII,IB and IIB.

In d block elements, the electron gets filled in the d orbital of the penultimate shell. That is why, these elements are known as TRANSITION  ELEMENTS.

Though the total number of d block elements is 33 in the periodic table but there are 30 transition elements. Because only those elements are transition in which d orbitals partially filled.

The general formula of these elements is (n-1)s²,p⁶,d¹-¹⁰, ns¹-² where n = 4 to 7.

All of these elements ARE metals.

Out of all the d block elements MERCURY  is the only liquid elements.

There are four series in the d block corresponding to the filling up of 3d,4d,5d or 6d orbitals.

3d = Sc,Ti, V,Cr, Mn, Fe, Co, Ni, Cu,Zn.
4d = y, Zr, Nb, Mo, Tc, Ru,Rh, Pd,Ag, Cd.
5d = La,Hf, Ta , W  Re, Os, Ir, Pt,Au,Hg.
6d = incomplete.


FIRST TRANSITION SERIES :-

SC =  4S²,3d¹.
Ti = 4s² 3d².
V  = 4s² 3d³
Cr= 4s² 3d⁴
Mn = 4s² 3d⁵
Fe = 4s² 3d⁶
Co = 4s² 3d⁷
Ni = 4s² 3d⁸
Cu = 4s² 3d¹⁰
Zn= 4s² 3d¹⁰.


SECOND TRANSITION SERIES:-

Y = 5s²,4d1
ZR = 5s²,4d2
Nb = 5s²,4d4
Mo = 5s²,4d5
Tc = 5s²,4d5
Ru = 5s¹,4d7
Rh = 5s¹,4d8
Pd = 5s⁰,4d¹⁰
Ag = 5s¹,4d¹⁰
Cd = 5s²,4d¹⁰.

THIRD TRANSITION SERIES:-

La  = 6s²,5d¹
Hf = 6s²,5d²
Ta = 6s²,5d³
W = 6s²,5d⁴
Re = 6s²,5d⁵
Os = 6s²,5d⁶
Ir = 6s²,5d⁷
Pt = 6s¹,5d¹⁰
Au = 6s¹,5d¹⁰
Hg = 6s²,5d¹⁰.



F- BLOCK ELEMENTS:-


The elements of the periodic table in which the last electron gets filled up in the f orbital,called f block eleemnts.

The f block elements are from atomic number 58 to 71 and from 90 to 103.

The lanthanide occur in nature in low abundance and therefore, these are called rare earth elements.

There are 28 f block elements in the periodic table.

Elements from atomic number 48 to 71----- LANTHANIDES.

Elements from 90 to 103--------- ACTINIDES.


*All actinide elements are radioactive.

*All the elements after atomic number 92(i.e. U⁹²) are transuranic elements.

* The general formula of these elements is (n-2)s²p⁶d¹⁰ ns².

where n =6 and 7.




*THANK YOU FOR READING*.

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