An electron revolving in a stationary orbit of an atom absorbs some energy the electron may jump over to an orbit of higher energy. This process is called excitation and the atom is said to be in the excited state. The energy absorbed to move from one orbit to the other is called excitation potential.
If the energy supplied is large enough to remove an electron from the atom, then the atom is said to be ionized. The minimum energy needed to ionize an atom is called Ionisation energy. Here the removed electron will have zero energy. Therefore the Ionisation potential of a hydrogen atom in the ground state is 13.6 eV.
Calculate the energy of a He+ ion in its first excited state
Here z = 2 and for the first excited state n = 2.
= -13.6 eV
