||The English used in this article may not be easy for everybody to understand. (February 2012)|
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, which is called a nucleus. A lump of uranium that is dug out of the ground will be made from three different isotopes, that is three different types of uranium with different numbers of neutrons in their nuclei. Most will probably be uranium-238, which has 238 protons and neutrons, a small amount will probably be uranium-235 with 235 protons and neutrons, and a very small amount will be uranium-234, with 234 protons and neutrons.
Uranium-235 can be used in nuclear reactors and nuclear weapons by having a neutron inserted into its nucleus by humans. This turns the uranium-235 into uranium 236 as the extra neutron is added to the 235 protons and neutrons already in the nucleus. This almost always splits the nucleus into two smaller nuclei. This makes two completely different elements with smaller atomic numbers. This process is called nuclear fission, and creates a huge amount of heat. This heat makes it very useful for making electricity in nuclear reactors, or for blowing things up with nuclear weapons.
Uranium is weakly radioactive. Uranium which has had all of its uranium-235 taken out of it is called depleted uranium. Depleted Uranium is very heavy and thick (as each atom has a lot of protons and neutrons). This makes it good for balancing weight in airplanes, and for making bombs which can destroy tanks easily. Uranium can also be used as a dye for glass or pottery, which is how it was used before people found out that it was radioactive and could be used for nuclear purposes.
Uranium is a dangerous substance. Because Uranium is radioactive it is often seen with the hazard sign for radioactive elements, a group of three triangles with curved outer edges pointing in towards the middle, as seen on the bottle on the right. A lot of people believe that Uranium is a light green, glowing colour. However, this is completely untrue, because Uranium is black.