Why do we need electron configurations?
When atoms come into , it is the outermost electrons of these atoms, or valence shell, that will interact first. An atom is least stable when its valence shell is not full.
The valence electrons are responsible for an element’s chemical behavior. Elements that have the same number of valence electrons often have similar chemical properties.
They can also predict stability. An atom is most stable when all its orbitals are full. These configurations occur in the noble gases. The noble gases are very stable elements that do not react easily with any other elements.
Electron configurations can help us predict about the ways in which certain elements will react, and the chemical compounds or molecules that different elements will form.