system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How do glass and other transparent materials work on a molecular level? Do they have more space in between molecules? Does the light interact a lot less with their molecules? How does the light come through where in other materials the light is absorbed?
gpt
Glass does absorb light, but not in the visible spectrum. Molecules have molecular energy levels for their electrons (and atoms also have atomic energy levels the same way). When they absorb light, the energy of the light matches the energy difference between the energy levels, and an electron is promoted to a higher energy level. It just so happens that typically, the molecules in glass (mostly SiO2) don't have a difference in energy levels corresponding to the energy of visible light. They do happen to have a difference in energy level that corresponds to light in the UV spectrum, hence UV light does not pass through normal glass very easily (unless it's pure SiO2). This also means you're unlikely to get a sunburn in your car with the windows up.

It also happens that the glass molecules are generally not the right size or shape to scatter visible light either very much. However there is some light reflected from the surface because glass has a different refractive index than air (ie. light travels slower through glass). At any boundary where there is a refractive index change, some light will usually reflect (see the Fresnel Equations). Hence if the surface of the glass is not smooth, it will reflect light in many directions, and it will effectively scatter light at the surface. 

EDIT: like Mariofosheezy pointed out, also remember that most matter is not very dense, most of the volume is made up the "electron clouds" hence if the molecular orbitals of the glass don't interact much with the light, then it is basically passing though 99.9% empty space as far as it's concerned. 

EDIT2: It get's more complicated than this. Many other materials have other properties that make it so that visible light can't really pass through. Some have very good absorbance in the visible spectrum, others have very densely packed molecules/atoms that attenuate light very rapidly, etc.