Atomic Number: 92
Phase at Room Temperature: Solid
Element Classification: Metal
Period Number: 7 Group Number: none Group Name: Actinide
Phase at Room Temperature: Solid
Element Classification: Metal
Period Number: 7 Group Number: none Group Name: Actinide
Radioactive
What's in a name? Named for the planet Uranus.
Say what? Uranium is pronounced as you-RAY-nee-em.
You know uranium as a radioactive element, found in bombs, nuclear power plants and hardened metals. It's also found in some decorative glassware, called "vaseline glass", where the uranium compounds contribute a yellowish-green fluorescent color. How much do you know about this element?
- Pure uranium is a silvery-white metal.
- The atomic number of uranium is 92, meaning uranium atoms have 92 protons and usually 92 electrons. The isotope of uranium depends on how meany neutrons it has.
- Because uranium is radioactive and always decaying, radium is always found with uranium ores.
- Uranium is slightly paramagnetic.
- Uranium is named for the planet Uranus.
- Uranium is used to fuel nuclear power plants and in high-density penetrating ammunition. A single kilogram of uranium-235 theoretically could produce ~80 terajoules of energy, which is equivalent to the energy that could be produced by 3000 tonnes of coal.
- Natural uranium ore has been known to fission spontaneously. The Oklo Fossil Reactors of Gabon, West Africa, contain 15 ancient inactive natural nuclear fission reactors. The natural ore fissioned back at a prehistoric time when 3% of the natural uranium existed as uranium-235, which was a high enough percentage to support a sustained nuclear fission chain reaction.
- The density of uranium is about 70% higher than lead, but less than that of gold or tungsten, even though uranium has the second-highest atomic weight of the naturally occurring elements (second to plutonium-244).
- Uranium usually has a valence of either 4 or 6.
- Health effects of uranium typically are not related to the element's radioactivity, since the alpha particles emitted by uranium cannot even penetrate skin. Rather, the health impact is related to the toxicity of uranium and its compounds. Ingestion of hexavalent uranium compounds can cause birth defects and immune system damage.
- Finely divided uranium powder is pyrophoric, meaning it will ignite spontaneously at room temperature.
