Marie and Pierre Curie shared a Nobel Prize

Marie and Pierre Curie shared a Nobel Prize with Becquerel in 1903. They discovered radium, an element a million times more radioactive than uranium. They also coined the word “radioactivity, ” from the Latin word “radius, ” which means “ray. ” (Radioactivity never had anything to do with radio. ) Scientists now understand the nature of radioactivity. The nuclei of radioactive isotopes spontaneously disintegrate (which means break down by themselves). This emits three kinds of energetic particles: alphas, betas, and gamma rays. Pierre died in a carriage accident in 1906. He never got to use the fine laboratory built with the Nobel Prize money. Marie would later die of leukemia, from all the radiation.

Radioactive decay can show old things are. Tritium (hydrogen-3) decays into helium-3 with a half-life of 12. 3 years. Carbon-14 decays into nitrogen-14 with a half-life of 5, 730 years. Uranium-238 decays into thorium-234 with a half-life of 4. 5 billion years.

Neutrinos are ghostly particles made by nuclear reactions in the Sun. One trillion neutrinos pass through every square centimeter of you every second.

Nuclear fission is how a conventional nuclear reactor works. Heavy nuclei are split by neutrons. Uranium-235 or plutonium-239 can sustain a chain reaction. 1 kg of U-235 has the energy of 14, 000 barrels of oil or 3, 000 tons of coal. Nuclear waste is radioactive, and needs to be stored safely for over 10, 000 years.