Interactive decay chamber: choose alpha, beta-minus, beta-plus or gamma decay, fire the emission, and watch the nuclear equation balance and the radiation get stopped by paper, aluminium or lead.

One shot from the nucleus and the atom becomes a different element

Alpha, beta and gamma decay are how an unstable nucleus calms down: it throws out a particle or a burst of energy. What it throws decides what it turns into, how hard it hits nearby atoms and what can stop it. Pick a decay, then raise the emission progress to fire it.