Photon Beam Hitting Atom

[Jack Van Ryan 1A]

When a photon beam hits an atom, does it excite an electron from n=1 first or is the energy level of the electron that's excited random? In other words, does the radiation from the photon excite all of the atoms or just one from a particular energy shell? I'm really confused on how the photon "picks" one particular electron to excite.

Thank you.

[Jessy Ji 2J]

Hi,

I believe when the photon energy of the light equals to the change in energy between the energy level, all the electron will get excited to that energy level. However, if the energy of the photon does not reach the exact delta E value between the energy levels, the electron would not absorb that wavelength of light therefore not excited. Then, after the electrons are excited, they go back to the ground level n=1.