# Why electron does not lose energy in orbit when revolving around nucleus [duplicate]

Why electron does not fall into nucleus from orbit of an atom? As accelerated charged particle radiates energy, it should lose energy.

• – Omry
Commented Oct 11, 2017 at 18:14
• Electrons "rotating" around the nucleus do lose energy and jump to a"lower orbit", if it is not taken. Once all "lower orbits" (energy levels) are filled up, electrons have nowhere to fall. According to the Pauli exclusion principle, two electrons cannot share the same energy level (same reason why we can't go thorough a wall). Commented Oct 11, 2017 at 18:23

Quantum Mechanics provides a refinement to this idea; for the lowest energy states inside the Hydrogen atom, the energy states simply aren't continuous. They go like $E_{n}=-k/n^{2}$, for positive integers $n$. So the electron cannot "continuously" lose energy; when it does gain or lose energy, it transiently gains or loses photons to move from one discrete energy level to another.
When the electron is momentarily in a very large $n$ Hydrogen atom state, it may emit photons each of very small spurts of energy $k(\frac{1}{n^{2}}-\frac{1}{(n+1)^{2}})\propto \frac{1}{n^{3}}$, and almost continuously "fall" in the ladder of energy states, till it reaches the $n=1$ energy state. This is where you get the approximate classical behaviour.