Missouri Dmv On Koch Road Exercise 3: "Atom"

ny or too few neutrons relative to the number of protons, the nucleus is unstable and subject to

radioactive decay
. The electrons surrounding the nucleus occupy a set of stable

energy levels

, or orbitals , and they can transition between these states by the absorption or emission of photons that match the energy differences between the levels. The electrons determine the chemical properties of an element, and strongly influence an atom's magnetic properties.   Fuente: http://en.wikipedia.org/wiki/Atom