How can changes of electron energies produce a line emission spectrum?
when an electron changes (drops) from a higher energy state to a lower state a photon is emitted. The frequency (colour) of the photon is given by Plancks equation. The electrons associated with line spectra are bound to atoms rather than being free electrons that can have any energy. Quantum theory tells us that these bound electrons can only have certain values for their energy states. Hence not every possible transition (change of energy value) is possible and the result is the photons (light) that are emitted only occurs at discrete frequencies. There is a lot more going on than this simplified explanation covers. Different “storage times” result in different phenomena such as luminescence and phosphorescence. Also the line spectra are not absolutely sharp. Watch out for descriptive terms like orbits, levels, and jumps. These may help us to visualise what is going on but don’t have any real world significance.
