- 1.According to Bohr atom model the electrons are revolved around the nucleus in a fixed
circular path is called orbit.
- 2.The maximum electron embedded in 1st shell(K) =2
- 3.The maximum electron embedded in 2nd shell (L)=8
- 4. The Maximum electron at 3rd shell(M) = 18
- 5.Accordingly electron in each energy level are arranged in its sub energy level
6.Each sub energy level in a shell is called a sub shell,They are named as s p d & f
- 7.Electron filling in different sub shells takes place in the increasing order of their
energies.ie the sub shell which has the lowest energy level is filled first.
- 8. The increasing order of sub shell can be identify from the following diagram.
- 9.Based on the sub shell electronic configuration, elements are classified into four
different blocks as s p d & f.
- 10.The block to which the element belongs will be the same as the sub shell to which
the last electron is added.
- 11.the period number is same as the shell number of the outermost shell in the sub shell
- 12.for s block elements the number of electron in the outer most s sub shell
will be the group number
- 13.Pblock: Group number is obtained by adding 12 to the number of electron present in the outermost p sub shell
- 14.Dblock:the group number of d block elements will be the same as the sum of electrons in the outermost s sub shell and the number of electron in the preceding d sub shell
Characteristics of s block elements:
- 15.Their oxide and hydroxides are basic in nature.
- 16.S block elements usually form ionic compounds
- 17.More metallic nature
- 18.Low ionization energy
- 19.Low electro negativity
- 20.Elements in 1st & 2nd group are belong to s block elements.( 1st group element is alkali
- metals and 2nd group elements is alkaline earth metals)
- 21.Oxidation state of 1st group element is +1 &oxidation state of 2nd group elements is +2
- 22.High atomic radius.Last electrons are filled in s sub shell
Characteristics of p block elements:
- 23.P block contains metals, non metals and metalloids.
- 24.The last electron is filled in p sub shell 25.High ionization energy
- 26.High electro negativity
- 27.P block elements shows both +ve and –ve oxidation state.
Characteristics of d block elements:
- 28.The last electron is filled in the d sub shell
- 29. Their elements are also known as transition elements.
- 30.All d block elements are metals.
Characteristics of f block elements:
- 31 the element in which last electron enter into the f sub shell
their elements are also known as inner transition elements.
Their elements are placed in two separate rows at the bottom of the
- 32 1st row known as lanthanoids
- 33.2nd row known as actinoids
- 34.Most of the elements shows variable oxidation state liked block elements
Most of the actinoids are artificial elements.
Uranium(U), thorium (Th), plutonium (Pu) etc… are used as fuel in
- 35.Many of these elements are used as catalyst in the petroleum industry.