Lead
Lead is the heaviest atom that is still stable, with 82 protons and 125 neutrons, just a little heavier than mercury. Unlike many other metals, lead does not conduct electricity well.
All of the lead in the universe came originally from inside stars.
Because lead has so much mass, people use it for weights and for bullets. The large mass gives it a lot of momentum. Lead is also very soft and doesn't corrode (rust) very much, so people use it for building, for instance to seal joints in roofs so the water doesn't get in.
Learn by Doing - Lead
To find out more about atoms, check out these books from Amazon.com or from your library:
