# Bohr model of hydrogen atom

According to Bohr model of hydrogen atom, the electron orbits in circular orbits around the nucleus. when I'm asked to find the energy needed to ionize the hydrogen atom, I calculate the energy stored in the electron. this energy is consisted of kinetic energy and electric potential energy.

But, I was said that in order to get more precise results, I I have to calculate the "Reduced Mass" of the problem because the nucleus also orbits around the center of mass.

My question is why do we care about the velocity/movement of the nucleus in calculating the energy of the electron? solving the "reduced mass" problem gives my the energy of "the whole system" instead of the single electron. so why do we need to do that? is the energy of the electron changes somehow when the nucleus also orbits around the center of mass?

• The hydrogen ground state has ${\cal l } =0$ so the Bohr model is not correct. Then why bother working with it? Dec 16, 2021 at 23:01

So you can't remove only the electron, ionization applies to the whole atom. Treating it as if the whole energy is in the electron is an approximation, where proton mass is assumed to be much larger than electron mass: $$m_{\text p}\to\infty$$.