Transmutation

In 1919, Ernest Rutherford (the man who discovered the nucleus) and his research group became the first people to cause transmutation - the changing of one nucleus into another. While they didn't change lead into gold, they were the first to control a nuclear change instead of simply relying on nature. They shot a sample of the isotope Nitrogen-14 with a beam of alpha particles as shown below:

14 4 17 1 N + He → O + H 7 2 8 1

If you look carefully, you'll note that they actually caused transmutation in two elements: Nitrogen-14 became Oxygen-17, and Helium-4 (the alpha particle) became Hydrogen-1. Over the years, scientists have smashed different elements together to create a large number of different isotopes, many of which do not exist in nature.

Neutrons also can be used to cause transmutation, as we'll see next.