What is the cause of discrete or quantized energy levels in an atom?
1048
Discreteness of set of energy eigenvalues
24189
What exactly is a bound state and why does it have negative energy?
122561
Is the energy always discrete?
113472
Quantum mechanics and everyday nature
91879
Atomic Physics: stimulated emission
70774
Why can't the Schrödinger equation be solved exactly for multi-electron atoms? Does some solution exist even in principle?
629
How are Quantum Mechanical energy levels related to atom shells?
86295
Creation and annihilation operators in the hydrogen atom
8760
Is the harmonic oscillator potential unique in having equally spaced discrete energy levels?
13443
Where are the inaccuracies in the Bohr model of the atom?
137837
Why electrons can't radiate in their atoms' orbits?
73049
Quantum Zeno effect and unstable particles
1584
Why does spin have a discrete spectrum?
20997
Can an electron jump to a higher energy level if the energy is insufficient or exceeds the $\Delta E$?
14989
In quantum mechanics, given certain energy spectrum can one generate the corresponding potential?
10504
What are the reasons to expect that gravity should be quantized?
34829
Why is water blue (on a quantum level)