3(a).Modern Periodic Table (s-block & p-block)

Classification on the basis of differentiating electron

Do you ever think why periodic table is classified into four block i.e s, p, d and f ?

Let's find it answer . In earlier we see the electronic configuration  of some element.Periodic table is classified into four block on the basis of last electron entering in the orbital and due to this orbital these elements are classified into that particular block.

Let's take some example to more clear

Here you can see in first example last electron of potassium is entering in s orbital and so it is classified as s-block element.Similarly Carbon is classified as p-block element,Chromium is classified as d-block and cerium is classified as f-block element (i.e lanthanide).

# s-block element : 

If the last electron enter into the s-orbital then the element belongs to s-block as you saw in the above example.As the capacity of s-orbital is 2,there are two vertical column in s-block. since upto only 2 electron will insert in s-orbital ,so there are only two elements insert in vertical column.

                       IA             IIA

                        H              Be                    *IA is named as alkali metal whereas IIA is named as 

                        Li             Mg                      alkaline earth metal.

                        Na            Ca

                        K              Sr

                        Rb             Ba

                        Cs             Ra

                        Fr              

→General electronic configuration is ns¹ ns².

⇢General oxidation state for group-1 is '+1' and group-2 is '+2'.
Here important point to be noted is general oxidation state mean the stable oxidation state.
→s-block elements are electro-positive in nature and they are named as soft-metal ( due to weak metallic bond ).
→s- block element have low melting and boiling point.
we will see the more property related with s-block element in upcoming blog.

# p-block element :

If the large electron enter into the p-orbital ,then the element belong to p-block.

      13                    14                     15                    16                     17                   18

IIIA	IVA	VA	VIA	VIIA	0
B Boron	C Carbon	N Nitrogen	O  Oxygen	F  fluorine	Ne Neon
Al Aluminum	Si  Silicon	P Phosphorous	S Sulfur	Cl Chlorine	Ar  Argon
Ga Gallium	Ge  Germanium	As  Arsenic	Se Selenium	Br Bromine	Kr Krypton
In Indium	Sn     Tin	Sb Antimony	Te tellurium	I Iodine	Xe Xenon
Tl Thallium	Pb Lead	Bi Bismuth	Po Polonium	At Astatine	Rn Radon

• The maximum capacity of  p-orbital is 6. So there are 6 group in p-block classification and there are six electron in outermost orbit of 0th-group element.
• General electronic configuration is ns²np^1-6 .

            Ex.         B                C              N               O                 Cl               Ne    

                       2s² 2p¹      2s² 2p²      2s² 2p³      2s² 2p⁴         2s² 2p⁵       2s² 2p⁶.

• Oxidation State : Oxidation number of p-block varies from 'n' to ( n-8 ) ,where 'n' is no. of valance electron. 

          Ex.             B                C                 N                    O                  P
                      [+3 to -5]    [+4 to -4]      [+5 to -3]       [+6 to -2]       [+7 to -1]

Note :

•  In case of halogen (group-VIIA or 17) oxidation number is +7 to -1 but it is not applicable for  'F' due to absence of d-orbital.

          See the electronic configuration of F (At no. 9)--> 1s² 2s² 2p⁵  due to absence of d- orbital                   the oxidation number is 0 to -1 only.
           for more detail to understand the concept of oxidation go through the following link :         

• Oxidation number of oxygen varies from -2 to +2.

             O --> 2s² 2p⁴
           for peroxide -->  H₂ O₂                 H⁺¹  --  O^-1 --  O^-1  --  H⁺¹.
           for superoxide --> O₂^-1...         Oxidation = -1/2

• Nitrogen can exhibits '+5' oxidation number only in case of HNO₃ but it is not general oxidation number because 'N' can't form 5-bond.

Hope you know how to find  oxidation number otherwise we will see in more detail in upcoming blog.Don't be nervous we have a trick to finding oxidation state, just wait.

Now we will see some of the important definition

 ✱ Lower -Oxidation number : Oxidation number due to the e- of  'p' orbital in the valence shell.

Ex.       B          C           N           O             F

          +1          +2          +3          +4           +5   ------> Due to p-orbital 

✱ Maximum-Oxidation number :   Oxidation number due to the e- of  's' and  p-orbital.

Ex.         B          C           N           O             F

             +3         +4          +5         +6            +7

✱ Minimum-Oxidation number :  Number of electron gained for completing the octet.
       
                           Minimum oxidation state = n-8

Hope you 're understanding the concept ,if you have any doubt don't hesitate to write in comment section.
                 Thanks..........