When they struck atoms in the glass wall, they excited their orbital electrons to higher energy levels, causing them to fluoresce.

More recently, however, many nuclear theorists have come to believe that the atomic nucleus, in common with the atom's orbital electrons, is structured in shells.

Even the orbital electrons within your body's atoms are kept from moving ... but don't worry about the physical danger of it, that's extremely small.

It takes a lot more energy to kick out lower orbital electrons, so the energy has to be in the x-ray to make this happen.

When electrons collide with molecules of air in the gap, they excite their orbital electrons to higher energy levels.

Basically, lots of outer orbital electrons with similar energies.

Generally, larger atoms are more likely to absorb an X-ray photon since they have greater energy differences between orbital electrons.

Thorium doesn't have an outer f orbital electron, but I can rationalize the rare earths beginning here.

Atomic orbital electrons move around their nuclei at a big fraction of our normal speed of light.

When they strike atoms in the glass, they knock their orbital electrons into a higher energy level.