Cesium Selenide

See more Cesium products. Cesium (or Caesium) (atomic symbol: Ce, atomic number: 55) is a Block S, Group 1, Period 6 element with an atomic weight of 132.9054519. The number of electrons in each of Cesium's shells is 2, 8, 18, 18, 8, 1 and its electron configuration is [Xe]6s¹. The cesium atom has a radius of 265 pm and a Van der Waals radius of 343 pm. Cesium is a member of the alkali group of metals. It is one of three metals that occur as a liquid at room temperature, the others being mercury and gallium. Cesium's main commercial source is pollucite ore; however, it is also found in beryl, avogadrite, pezzottaite, and londonite. Cesium was discovered by Robert Bunsen and Gustav Kirchhoff in 1860 and first isolated by Carl Setterberg in 1882. In its elemental form, cesium has a silvery gold appearance. The word Cesium originates from the Latin word "caesius," meaning "sky blue," which refers to the vibrant blue lines in its spectrum.

See more Selenium products. Selenium (atomic symbol: Se, atomic number: 34) is a Block P, Group 16, Period 4 element with an atomic radius of 78.96. The number of electrons in each of Selenium's shells is 2, 8, 18, 6 and its electron configuration is [Ar] 3d¹⁰ 4s² 4p⁴. The selenium atom has a radius of 120 pm and a Van der Waals radius of 190 pm. Selenium is a non-metal with several allotropes: a black, vitreous form with an irregular crystal structure three red-colored forms with monoclinic crystal structures and a gray form with a hexagonal crystal structure, the most stable and dense form of the element. One of the most common uses for selenium is in glass production the red tint that it lends to glass neutralizes green or yellow tints from impurities in the glass materials. Selenium was discovered and first isolated by Jöns Jakob Berzelius and Johann Gottlieb Gahn in 1817. The origin of the name Selenium comes from the Greek word "Selênê," meaning moon.