stimulation: http://phet.colorado.edu/en/simulation/alpha-decay

• The half-life of the Polonium-211 nucleus is approximately 500 ms. The nucleus decays by emitting an alpha particle. How does this alpha particle make it out of the nucleus. (Watch what happens in the bottom-half of the display in "Single Atom" mode.)
• After the Polonium-211 nucleus has decayed, a lead-207 nucleus is left behind. Why does lead-207 not decay by emitting an alpha particle?
• The half-life of the Polonium-211 nucleus is approximately 500 ms. What do you observe in "Multiple Atoms" mode, when you monitor approximately 100 nuclei?
• In "Single Atom" mode switch to a custom nucleus. What can you do in the bottom-half of the display to build a nucleus with a half-life of a billion years?