Question

What causes excitation of atoms?

Answer 1

ENERGYYYYYYY

That's the best I got for a short answer :D

Explanation:

Photons are discrete energy packets and this can help with a myriad of things in chemistry.

Let's say you're a year 12 student in the UK like I was last year and we're discussing emission and absorption spectra.

So when an atom receives energy, it absorbs that energy to excite the electron(s) by using the energy from said photon, or an electron beam, or by the application of heat.

This will excite electrons so they jump up energy levels, but like a rocking sesh, at some point, it all must die down -- This was honestly the best analogy I had. --

So the electrons return to their original state, and when doing so release energy, usually in the form of discrete photons or light, which corresponds to discrete (quantized) energy levels, as specific wavelengths of light are needed; the jump from one shell to the next is quantized.