The Hydrogen Atom (Bohr)
The Hydrogen Atom is the smallest and simplest atomic system. It consists of 1 proton and 1 electron. The electron exists in an energy level characterized by an integer quantum number universally called “n”.
The energy of the electron when it is in the n’th state is En = -RH/n2. RH is the Rydberg constant, whose value is 2.18x10- 18 Joule.
The lowest (legal) value of “n” is 1 (not zero).
If an H-atom is in the state n and it makes a transition to the state n’ (n-prime) the difference in energy corresponds to the energy of the photon either absorbed or emitted as the transition took place.