Nuclear Chemistry 25.1 Radiation 25.2 Nuclear Transformations Difference between radioactivity, radiation, radioisotopes Learn the three main types of radiation What is the band of stability? Radioactivity and half-life

Radioactivity Discovered by Antoine Henri Becquerel in 1896 – He saw that photographic plates developed bright spots when exposed to uranium metals

The Experiment That Started it All Marie Curie and Antoine Becquerel-1896 They were studying effect of uranium salts that were exposed to sunlight and fogged photographic film. On cloudy day, he left uranium on film and it made this image.

Definitions Radioactivity - Process by which substances give off the rays that fogged the photographic film Radiation - What the actual rays are called Radioisotopes - Unstable isotopes that become stable by emitting energy and radiation

The Radium Girls Grace Fryer and the other women at the radium factory in Orange, New Jersey, naturally supposed that they were not being poisoned. It was a little strange, Fryer said, that when she blew her nose, her handkerchief glowed in the dark. But everyone knew the stuff was harmless. The women even painted their nails and their teeth to surprise their boyfriends when the lights went out. They all had a good laugh, then got back to work, painting a glow-in-the-dark radium compound on the dials of watches, clocks, altimeters and other instruments.

Three Main Types of Radiation Alpha Beta Gamma

Alpha Radiation Loss of an  -particle (a helium nucleus) He 4242 U  Th He

Alpha Radiation

Beta Radiation

Gamma Radiation Loss of a  -ray (high-energy radiation that almost always accompanies the loss of a nuclear particle)  0000

Radiation Comparisons

Band of Stability Nuclei above this belt have too many neutrons. They tend to decay by emitting beta particles.

Stability of Nuclei There are no stable nuclei with an atomic number greater than 83. These nuclei tend to decay by alpha emission.

Half-Life Half Life (t 1/2 ) is the time required for half the atoms of a radioactive nuclide to decay. Carbon-14 has a half life of 5715 years. If you had 20 mg of C-14 the following would be true … Years Amount C-14 left (mg)