Valency Formula
The combining capacity of an atom with atoms of other Elements in order to acquire (8 electron) that stable electronic configuration is called Valency.
The outer most shell of the elements is called valence shell or valence electrons.
- The distribution or arrangements of electron in different shell of the atom is called electronic configuration Of the elements.
- The arrangements of electron in different shell should be such that it should have Maximum stability. Thus to write electronic configuration of an element, we should know
- Total number of electron presents in the atom . This is equal to the number of protons ( that is atomic number) for a neutral atom.
- Maximum number of electron that can present in each shell of atom . This is given by Bohr-Bury scheme.
2n2 n= designation. K shell (n=1) , L shell (n=2) , M shell (n=3) , N shell (n=4) ,
Shell |
N | 2n2 | Maximum number of electron |
K | 1 | 2(1) 2 |
2 |
L |
2 | 2(2) 2 | 8 |
M | 3 | 2(3) 2 |
18 |
N |
4 | 2(4) 2 |
32 |
Atomic number:
Atomic number is The number of protons present inside the nucleus of atom.
Atomic mass:
Atomic mass is number of protons and number of neutron present inside the nucleus of atom.
- To calculate the Valency of an element the electronic configuration of elements first written. Than the Valency of elements is calculated.
- For elements having valence electrons 1,2 or 3 Valency is equal to the valence electrons .
- For elements having valence electrons 4,5,6,or 7 Valency is equal to the number of electrons to be added so that the valence shell has 8 electron.
Formula;
valency= 8 – number of valence electron
Question-1:
Calculate the Valency of oxygen atom?
Solution:
Electronic Configuration of oxygen:. 2,6
Formula;
valency = 8 – number of valence electron
Valency =. 8 – 6
Valency = 2
Question-2:
Calculate the Valency of Nitrogen atom?
Solution:
Electronic Configuration of Nitrogen:. 2, 5
Formula;
valency= 8 – number of valence electron
Valency = 8 – 5
Valency = 3