The number of electrons lost, gained or shared by an atom of an element is known as ………………………
Electro valency - The number of electrons of an element that take part in a chemical reaction to attain nearest noble gas configuration is known as its valency
For example,
Sodium () - 2, 8, 1. Sodium donates its outermost electron to attain the configuration of nearest noble gas . So its valency is 1
Oxygen () - 2,6. Oxygen accept two electrons to attain nearest noble gas configuration. So its valency is 2 .
Therefore, the number of electrons lost, gained or shared by an atom of an element is known as electro valency.