PPT Slide
the systems we are interested in has many available quantum states
- many states can have identical energy --> multiplicity (degeneracy) of a level: number of quantum states with the same energy
- it is the number of quantum states that is important in thermal physics, not the number of energy levels!
Examples for quantum states and energy levels of several atomic systems:
(multiplicity for each energy level shown in the brackets)
1. Hydrogen (one electron + one proton)
2. Lithium (3 electrons + 3 protons + 3-4 neutrons)
3. Boron (five electrons + 5 protons + 5-6 neutrons)
4. Particle confined to a cube
nx, ny, nz --> quantum numbers : 1, 2, 3, …k,...
Quantum states of one particle systems --> orbitals