Answer the following :
What is meant by valency of an element ? what is the relationship between the number of valence electron and valency ?
Valency of an element : It is the number of electrons of an atom of the element uses to combine with atoms of other elements.
It is the combining power of an atom of the element.
Valency of an atom is determined by its electronic configuration.
It gives idea about the number of electrons loss or gain in order to achieve the nearest noble gas configuration.
For example: Na(11) = 2,8,1 So, its valency is 1
Cl(17) = 2,8,7 So, its valency is also 1
Number of valence electron : It is defined as the number of electrons present in the outermost shell of an atom.
It is not necessary that all the valence electrons take part in bonding.
For example: Na(11) = 2,8,1 So, its number of valence electron is 1
Cl(17) = 2,8,7 So its number of valence electron is 7
It can be seen that valency of an element is related to number of valence electrons in that atom.