Question

what can be added to an atom to cause a nonvalence electron in the atom to temporarily become a valence electron?
energy
mass
neutrons
electrons

Explanation:

When energy is added to an atom, electrons can absorb this energy. Non - valence electrons (electrons in inner shells) can gain enough energy to jump to a higher energy level (valence shell). Mass is a property of matter related to the amount of substance and is not directly involved in making a non - valence electron a valence electron. Neutrons are neutral particles in the nucleus and do not affect electron energy levels in this way. Adding electrons would change the electron count but not make a non - valence electron in the original atom a valence electron (it would just add more electrons).

Answer:

energy