Definitions by PrivateDonut

radioisotope 

a radioactive isotope of a normally non-radioactive element. Can be produced artificially, by bombarding the element in question's nucleus with neutrons. This increases the number of neutrons in the nucleus to an unstable number.
Radioisotopes also occur naturally.

Carbon-14 is a radioisotope.

radioisotope by PrivateDonut February 10, 2005

Isotope 

Each element has many versions that contain a different number of neutrons in the nucleas. Each different version of the element is called an isotope.

Carbon-13 is and isotope of Carbon

Isotope by PrivateDonut February 10, 2005

nucleus

the central part of an atom.
Contains protons and neutrons.

The nucleus of Uranium-238 contains 92 protons and 146 neutrons

nucleus by PrivateDonut February 10, 2005

neutron 

a sub-atomic particle (particles that make up atoms) that carries no charge (is neutral).

Neutrons are neutral particles.

neutron by PrivateDonut February 10, 2005