Electrons hold the key to almost the whole of Chemistry. This is because only electrons are involved in changes that occur during chemical reactions.
Electrons within atoms occupy fixed energy levels, or often known as shells. These shells as numbered 1, 2, 3, 4, etc. The numbers are known as principle quantun numbers, or n. The lower the value of n, the closer the shell is to the nucleus and therefore the lower the energy level.
In a shell there are regions of space around the nucleus, within this space there's a high probability that you will find an electron with a given energy. These regions are referred to as atomic orbitals.
An atomic orbital is a region in an atom that can hold up to two electrons with opposite spins. Orbitials of the same type are grouped together…