What is Uranium?
{{Infobox uranium}} [[File:U,92.jpg|thumb|right|A small amount of uranium in a glass dish]] '''Uranium''' is a [[chemical element]] (a [[metal]]) on the [[periodic table]]. It has an [[atomic number]] of 92, which means that a uranium [[atom]] has 92 [[protons]] in its center, the [[Nucleus (physics)|nucleus]]. Uranium dug out of the ground is made from three different [[isotopes]]. The isotopes are different types of uranium with different numbers of [[neutron]]s in their [[Nucleus (physics)|nuclei]]. Most of it is uranium-238; [[uranium-235]] is less common; uranium-234 is the rarest. [[Pitchblende]] is the main [[ore]] that is mined for uranium. Uranium-235 can be used in [[nuclear reactor]]s and [[nuclear weapons]] by making a [[nuclear chain reaction]]. This turns the uranium-235 into uranium-236 and splits the nucleus into two smaller nuclei. This makes two completely different elements with smaller [[atomic number]]s. The process is called [[nuclear fission]] and creates lots of heat. This heat makes it very useful for making [[steam engine|steam]] in nuclear reactors, or for making [[explosion]]s with nuclear weapons. Most such weapons use [[plutonium]] made from uranium-238. Uranium is slightly [[radioactive]]. Uranium without its uranium-235 is called [[depleted uranium]]. It is less radioactive than natural uranium. It is used in [[anti-tank gun|anti-tank]] weapons. Uranium can also be used as a [[dye]] for [[stained glass]] or [[pottery]]. [[File:Radiation warning symbol.svg|thumb|A trefoil radiation warning]] Uranium is a dangerous substance. Because uranium is radioactive it is often seen with the hazard sign for radioactive elements, a group of three [[triangle]]s with curved outer edges pointing in towards the middle (as you can see on the left). Uranium is a shiny white metal, but is usually seen in its [[oxide]] form which is black. Spent or partially spent uranium fuel rods are kept underwater, inside a nuclear reactor or in a spent fuel pool. Uranium can glow blue due to [[Cherenkov rad