The issue about why gasses produce specific lines of emission when they emit photons (corresponding to the gases energy levels) and why solids produce continuous spectrum.   

The best way to explain this is to refer to the notes we did on why Bohrís model is incomplete and is not a perfect model. Remember that Bohrís model broke down when dealing with many electron atoms. This is because Bohrís model didnít account for electrons interfering with each other.  

Gases have atoms that are far apart so the electrons are far enough apart that they do not interfere with each other. This is only true for elements with a low number of electrons. In atoms where there are a lot of electrons, Bohrís model breaks down.  However, in solid metals, there tend to be many electrons due to the higher atomic numbers, and the atoms are close together so the electrons are interfering with each other and therefore we do not get the specific lines of emission because the interference tends to alter the energy required to bump an electrons orbit. Furthermore, in a given solid, these energy levels from atom to atom and end up ďall over the mapĒ so almost any wavelength is a possibility.