Actinide Series of MetalsThere are two rows under the periodic table: the lanthanide and actinide series. The lanthanide series can be found naturally on Earth. Only one element in the series is radioactive. The actinide series is much different. They are all radioactive and some are not found in nature. Some of the elements with higher atomic numbers have only been made in labs. There are special laboratories across the world that specialize in experimenting on elements. Some of these particle accelerators have pounded atomic particles into elements with lower atomic numbers. The buildup of additional parts creates short-lived, high atomic number elements.
Meet the FamilyThe actinide family is comprised of fifteen elements that start with actinium (Ac) at atomic number 89 and finish up with lawrencium (Lr) at number 103. It's doubtful your teachers will ever ask you to remember all of the elements in the series. You have probably heard of plutonium (Pu), since it was used in atomic bombs. Uranium (U) is also well known for its radioactivity. They aren't all used to blow up the world. Some of them help us out every day. You can find americium (Am) is some metal detectors.
Higgs Boson: The Inside Scoop (Fermi National Accelerator Lab)