We love our demonstrations, but there are some things you can’t easily demonstrate in the classroom, either because the physics isn’t compatible with that environment, or because the scale is beyond what we can practically see. This is where simulations can be valuable, in letting us go beyond what we can do on the tabletop and look inside the black boxes.
The quantum nature of the hydrogen atom is a good example. We can demonstrate the emission spectrum of hydrogen with the Balmer Series demonstration P3-51, and we have simple models of electron orbitals for more complex atoms, but how can we look at the structure of the hydrogen atom itself?
Here are some simulations available for looking inside our smallest atom.
Falstad offers this illustration of the energy levels of the hydrogen atoms, which allows you to switch the view between the Bohr and Dirac models within a single active diagram https://www.falstad.com/nw/hydrogen.html
The PhET model hydrogen atom lets you compare different historical models of the atom to simulated experimental results https://phet.colorado.edu/sims/cheerpj/hydrogen-atom/latest/hydrogen-atom.html?simulation=hydrogen-atom
Andrew Duffy’s Emission Spectra simulator lets you compare the hydrogen spectrum with other visible spectra side-by-side with the full white light spectrum, for orientation http://physics.bu.edu/~duffy/HTML5/emission_spectra.html
This more complex Falstad simulator lets you display the wave functions/orbitals in either real or complex modes, and to take slices along the axes as well as viewing them in three dimensions. This is potentially valuable for upper level courses analyzing the orbital structure. http://www.falstad.com/qmatom/