When radium atoms inside solid radium turn into radon do they stay in their lattice positions at room temperature or do they diffuse/tunnel to the surface?
I was thinking of a lump of radium produced in a lab.Is this really your question? I believe that uranium is the first element of the decay series (4.4 billion year half life) which produces radium (1620 year half life) so one would not expect to find large volumes in nature.
If you are interested in radon gas in nature, the term is emanation is used. The idea is that when radium decays, the radon picks up enough momentum to move tens of nm in grain material and the question is whether the radon is trapped within the original grain, trapped in another grain or released to void.
What happens to the alpha particles?If the radon does not escape the grain immediately, then there will also be three alpha particles in the vicinity. One alpha was produced when radium decayed to radon, another alpha, a couple of days later when the radon decays to polonium, and then a third alpha a few minutes after that, as the polonium decays to lead.