The hydrogen atom is the simplest atom: it consists of a single 
proton and a single electron.Since it is so simple, it is possible 
PHY 231- ATOMIC PHYSICS 
 
Prof. Dr. Aisha Soliman 
mail: aisha_soliman@women.asu.edu.eg 55 |From these calculations it follows that the electron energy is 
quantized, and these energies are given by the expression: 
 where n is the principal quantum number of the atomic 
level, and 
is a fundamental physical constant called the Rydberg 
constant (here me is the electron mass).Numerically, 
Ry = 1.0974 x 105
cm-1 and hcRy = 13.605eV.P a g e
to calculate the energy spectrum of the electron bound states.