Nuclear Radiation 9.2

The Nucleus Protons and neutrons Charge of electrons and protons – x C = e –Proton +e –Electron -e

Isotopes Same element (number of protons), different number of neutrons Example: Protons on bottom, protons + neutrons on top

Strong Nuclear Force The force of attraction between nucleons (protons and neutrons) Binding energy—the total amount of energy that holds the nucleus together

Nuclear Binding Energy Mass defect –The mass of a stable nucleus is always less than the combined masses of the nucleons. –Mass is converted into energy –E=mc 2

Nuclear Binding Energy –Electron volt –eV—the amount of energy gained by an electron when accelerated through a potential difference of one volt –Nuclear binding energy = mass defect

Radioactivity Unstable elements spontaneously transform themselves into other isotopes of elements Alpha radiation Nuclear equation example:

Radioactivity Beta radiation –Electron emission—A neutron becomes a proton plus an electron –Positron emission—A neutron becomes a proton plus a positron (a positively charged electron) Nuclear equation examples:

Radioactivity Gamma radiation –High energy photons –No mass, no charge –Can be emitted with alpha and beta decay

Nuclear Fission When a nucleus absorbs a neutron, becomes highly unstable, and splits into two smaller nuclei. Other particles like neutrons can be emitted during fission –Chain reaction –Mass is converted into energy

Nuclear Fusion Two small high-speed nuclei combine to form a single larger nucleus. Source of energy for stars