How would you build a model that is ionized? what happens if an atom is too ionized? how would you build a model that is radioactive? what happens if the imbalance between protons and neutrons becomes too great

It will probably zip far from you and join itself to an adjacent molecule or atom. it gets to be distinctly radioactive when its core contains an excessive number of or an excessively couple of neutrons. Attempt to keep an indistinguishable number of neutrons and protons from you construct your iota. In the event that the awkwardness is excessively extraordinary, radioactive rot will happen.

Yes it would be a physical change.

The answer is a) carbon-12