2.Modern periodic table

Modified Periodic Table of Mendeleev's   

or Modern Periodic Table

Up to here we see the basic classification of periodic table and one of the most important classification Mendeleev's classification which play important to role in the periodic classification.

Basically Mendeleev gives the basic idea to classified the elements.

Modern Periodic law: According to modern periodic law the physical and chemical property of the elements are the periodic function of atomic number.

Important features of modified Periodic table

1. Complete Periodic table was classified in horizontal row (i.e period) and vertical (i.e group).
2. All the group was divided into sub group 'A' and 'B'.
3. A new vertical column was added and named as 'zeroth' group ( consist of inert gases).
4. The repetition in the property will start according to these number.                                                       2 ,  8 ,  8 ,  18 ,  18 ,  32
5. Lanthanide and actinide are separate from the main periodic table and named as inner-transition element.
6. Complete periodic table was classified into 7 period.

•  1st period --> very short period (2)   
•  2nd period--> short period (8)      
•  3rd period--> short period (8)  
•  4th period--> long period (18) 
•  5th period--> long period (18)       
•  6th period --> longest period(32)
•  7th period --> longest period (32) or incomplete period   

Drawback of Moseley's periodic table

1. Position of Hydrogen: same as Mendeleev's periodic table, Moseley's periodic table also could not give the exact position of hydrogen.
2. Elements having different property are placed together .                                                               for example : alkali-metal with (Cu,Ag,Au)
3. Similar element are placed separately .                                                                                      for example :  Pb and Ba
4. No explanation about the position of lanthanide and actinides ( inner transition element).
5. No explanation about the position of metal and non metal.
6. No explanation about the position of 12 transition element elements in the group-VIII.                EX--   Fe ,   Co ,   Ni                                                                                                                         Os ,   Ir  ,    Pt

These are the common drawback that are not define in the Moseley's P.T(i.e modern Periodic).Some of the other common drawback is also available that are not given till now.

Classification of P.T on the basis of electronic configuration

Now we will see how to configure the elements on the basis of their orbit i.e electronic configuration.

Electronic configuration of an elements gives the distribution of electron in orbit of an atom.

We all are familiar with s, p, d & f .

For detail understanding of electronic configuration and distribution of elements please go through following link:

Hope you will be understand it ,now we are coming to point .

Before going further see some example of electronic configuration of elements---

some example of electronic configuration     

some important definition 

• Inert Gas : Those element whose outermost shell is completely  filled. These are the group-VIII elements. Ex.  He ,  Ne ,  Ar ,  Kr ,  Xe ,  Rn                                                                                     General electronic conf. -->  ns²np⁶     

• Representative element : Those element whose outermost shell is incomplete are named as representative element.These are commonly p-block elements.                                                                   General electronic conf. -->  ns¹ or ns² np^1-6                                                     

              Ex.   Mg        Al               Si                  P               S                 Cl                                                                     3s²     3s² 3p¹       3s² 2p²        3s² 2p³       3s² 2p⁴       3s² 2p⁵

• Transition metal: Those metal whose outermost shell is incomplete as well as penultimate shell is incomplete.Here penultimate shell means shell before outermost shell.             Generally d-block elements are  known as transition  metal.  

                                   

Structure_of_atom

                                                               

                            General electronic conf. -->  (n-1)d^1-9 or ns²                                                                                Ex.

• Inner transition metal :  Those metal whose outermost shell is incomplete as well as penultimate and before penultimate is also incomplete.As you can see in the above picture and concentrate the shell before penultimate shell.

          General electronic conf. -->  (n-2)f^1-14  (n-1)d^0-1  ns²

 ↗                    ↑                 ↖   

                             before penultimate         penultimate     outermost

These are mainly f-block elements i.e lanthanide  and actinide.

go further to continue through following link :
              https://shrischool.blogspot.com/2020/05/3modern-periodic-table-s-blockp-blockd.html