Uranium is a weakly radioactive element with an atomic number 92 and symbol U in the periodic table. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. It is one of the heavy metals that can be utilized as a rich source of concentrated energy.
It was discovered in 1789 by Martin Klaproth, a German chemist, in the mineral called pitchblende. It was named after the planet Uranus, which had been discovered eight years earlier. The element exists in many rocks in the concentration of 2 to 4 ppm(parts per million) and common in Earth’s crust as tungsten and tin. It also exists in seawater and can be retrieved from the oceans.
Characteristics of Uranium
- Uranium has a melting point of 1132°C. The chemical symbol for uranium is U.
- Uranium was formed over 6.6 billion years ago. Though it is not common in the solar system, its slow radioactive decay provides a major source of heat within the Earth, responsible for continental and convection drift.
- Uranium’s high density means it also has applications in the counterweights of aircraft control surfaces and radiation shielding.
- It is one of the heaviest among all the naturally occurring elements when arranged based on the increasing mass of their nuclei on a scale. The element is 18.7 times denser than water.
- Uranium exists in various slightly different forms known as ‘isotopes.’ These isotopes are distinct in the number of uncharged particles in the nucleus.
- Natural uranium was found as a mixture of two isotopes. U-238 accounts for 99.3% and U-235 around 0.7%.
- Pure uranium is silver in color and readily oxidizes in air.
- It is also used to color glass that glows greenish-yellow in black light, not due to radioactivity because the glass itself is a bit radioactive. The fluorescence is because of the UV light that excites the uranyl compound in the glass and makes it let off photons when it settles down.
Applications and Uses of U
- The major application of uranium in the military sector is in high-density penetrators. This ammunition consists of depleted uranium (DU) alloyed with 1–2% other elements, such as titanium or molybdenum.
- At high impact speed, the density, hardness, and pyrophoricity of the projectile enable the destruction of heavily armored targets.
- Depleted uranium is also used as a shielding material in some containers used to store and transport radioactive materials. While the metal itself is radioactive, its high density makes it more effective than lead in halting radiation from strong sources such as radium.
- Other uses of depleted uranium include counterweights for aircraft control surfaces, as ballast for missile re-entry vehicles and as a shielding material.