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Periodic table

- The elements are classified into four types :-

* 1. Noble gases

They are found in p- block - in group zero.
They are stable ( completed last level).
k L

Example:

[10Ne] 1S2 2S2 2p6

* 2. The representative elements

They are found in s- block and p- block except (np6 and He).
They undergo reactions to complete their outer level.
k L M

Example:

(11Na) 1S2 2S2 2P6 3S1 3P 3d

* 3. The Transition elements

They are found in d- block.

They are incomplete the two highest levels nd,
(n+1) s

Example:

(21Sc)1S2 2S2 2p6 3S2 3p6 3d1 4S2 4p 4d 4f

* 4. The inner transition elements

They are found in f- block.

They are incomplete the three highest levels nf, (n+1)d , (n+2)S.

Example:

57La

* Description of the periodic table

It is consisted of 7 horizontal periods and 18 vertical groups.

Each period begins with new energy level and ends with Nobel gas.

Elements of the same group has the same configuration except the principle number.

1. The First period

It contains two elements-hydrogen 1S1 and He 1s2

The energy level is K.

2. The Second period

It consists of 8 element, 2 in s-block and 6 in p-block.

It begins with - Li3 (1 S2 , 2S1 )………. and ends with Ne10 (1 S2 , 2S2 ,2P6).

3- The Third period

It consists of 8 elements 2 in S and 6 in P

It begins with Na11, (1 S2 , 2S2, 2P6 ,3S1 )and ends with 18Ar

The sublevel 3d transferred to period 4 ( because it has higher energy than 4S) .

4- The fourth period

Its elements fill the forth level N and sublevel 3d - while 4d is transferred to period 5

They are 18 elements

It begins with k19 = [Ar18], 4S1 and Ca20 [Ar18 ], 4S2 Then 10 elements in d-block ( Transition elements).

Transition elements begin with Sc21=[Ar18],4S2 ,3d1 and end with 30Zn = [Ar18] , 4S2 , 3d10

Then 6 elements in p- block end with Kr36 = [Ar18] , 4S2, 3d10 , 4p6.

5- The fifth period

It begins with Rb37 = [ Kr36], 5S1 ,and end with Xe54 [Kr36], 5S2 , 4d10 , 5P6

They are l8 elements 2 in 5S -10 in 4d and 6 in 5p

6- The Sixth period

It has 32 elements -2 in 6S, - 14 in 4f (they are found under the table in order to be less length) -10 in 5d and 6 in 6P.

It begins with Cs55 = [ Xe54] , 6S1 and ends with Rn86 = [Xe54] , 6S2 , 4f14 , 5d10 , 6P6

The 14 elements in 4F are called Lanthanides (from inner transition elements).

7- The Seventh period

It has 2 elements in 7S and 14 in 5f(actinides ) and 6 in 6 d

It begins with Fr87 = [ Rn86] , 7S1 ….