The ground state of the hydrogen atom

So far we have focused on the atomic orbitals of hydrogen and have talked about the probability of finding an electron in different atomic orbitals. The most energetically favourable (stable) state of the H atom is its ground state in which the single electron occupies the 1s (lowest energy)  atomic orbital. The electron can be promoted to higher energy orbitals (see Section 1.4) to give excited states.  The notation for the ground state electronic configuration of an H atom is 1s¹, signifying that one electron occupies the 1s atomic orbital.