1, uranium
Uranium is an element with atomic number 92, and its symbol is U, which is the heaviest element that can be found in nature. There are three isotopes in nature, all of which are radioactive and have a very long half-life (hundreds of thousands to 4.5 billion years). Uranium was discovered by Martin Heinrich Klaproth in 1789. Uranium compounds were used to color porcelain in the early days and used as nuclear fuel after nuclear fission was discovered.
2. Plutonium
Plutonium is a radioactive element with atomic number 94 and element symbol Pu. It is an important raw material for the atomic energy industry and can be used as a fission agent for nuclear fuel and nuclear weapons. The atomic bomb dropped on Nagasaki used plutonium to make the core. Plutonium was first synthesized in 1940 and 12 at the University of California at Berkeley and Lawrence Berkeley National Laboratory.
3. Cesium
Cesium, element symbol Cs, atomic number 55, located in the sixth cycle, belongs to family IA. Its simple substance is a light golden active metal with low melting point, which is easily oxidized in air and can react violently with water to produce hydrogen and explode. Cesium has no elemental form in nature and is rarely distributed on land and sea in the form of salt. Cesium is an important material for manufacturing vacuum devices and photovoltaic cells, and it is also one of the radioactive pollution leaked from the Fukushima Daiichi nuclear power plant in Japan.
4. Strontium
Strontium is a chemical element with the symbol Sr, which is found between 179 1 and 1792. When the British chemist and Dr. Hope studied this ore, he was convinced that it contained a new kind of soil, so he named it strontian according to its place of origin. Strontium is a silvery white alkaline earth metal with yellow luster. It is the second least element in alkaline earth metals, second only to beryllium. Simple substance can be prepared by electrolytic melting of strontium chloride.
5. Iodine
Iodine, element symbol I, a nonmetallic element of element No.53 in the periodic table of elements, is located in the fifth cycle of the periodic table of chemical elements, and belongs to the ⅶ a family, one of the halogen elements. Elemental iodine was first discovered by French pharmacist Courtois B. in 18 1 1 year. Element iodine is a purple-black crystal, which is easy to sublimate, easy to condense after sublimation, toxic and corrosive. Elemental iodine turns blue-purple when it meets starch. Mainly used in the manufacture of drugs, dyes, iodine, test paper and iodine compounds.
Refer to the above content: Baidu Encyclopedia-Uranium