Promethium is a chemical element with the symbol Pm and atomic number 61. A gap in the periodic table was pointed out between neodymium at 60 and samarium at 62 by Bohuslav Brauner. After two false claims of discovery in 1926, in 1938 a few atoms of promethium were created but intentional production and chemical proof did not happen until 1945 at Ohio State University when promethium was extracted from irradiated uranium fuel. A sample of the metal was only produced in 1963.
Californium is a chemical element with the symbol Cf and atomic number 98. It is a silvery white actinide metal element that was first synthesized by bombardment of curium with alpha particles by a team at the University of California, Berkeley in 1950 and named for the state of California.
Technetium is a chemical element with the symbol Tc and atomic number 43. It is a silvery gray, crystalline transition metal in the same column of the periodic table as manganese, rhenium and bohrium. Early forms of Mendeleyev’s periodic table showed a gap above manganese and Mendeleyev predicted many of its properties from its position in the table in 1871.
Carbon is a chemical element with the symbol C and the atomic number 6. It has been known since ancient times. Graphite was named in 1594 by D.L.G. Harsten and A.G. Werner. Carbon was named by A.L. Lavoisier in 1789. It is a member of the non-metallic tetravalent (having 4 valence electrons) Group 14 in the periodic table which also includes silicon, germanium, tin, lead and flervium.
Strontium is a chemical element with symbol Sr and atomic number 38. It was discovered in 1790 by Adair Crawford, a physician, in ore taken from lead mines in the village of Strontian, Scotland and named after the village.
Cesium is chemical element with the symbol Cs and an atomic weight of 55. It was discovered in 1860 by Robert Bunsen and Gustav Kirchhoff with the new flame spectroscopy method. It is a soft, silvery gold alkali metal with a melting point of 28° C or 82° F and is one of only five elemental metals that is liquid near room temperature. It is highly reactive and pyrophoric. In open air, it will burst into flames and it reacts explosively with water.
Iodine is a chemical element with the symbol I and atomic number 53. It was discovered in 1811 by Frenchman Bernard Courtis in one of those luck accidents when he added too much sulfuric acid to ashes of seaweed that he was processing. The purple vapor that was given off crystallized out on nearby surfaces and was eventually given the name “iodine” derived from the Greek word for purple.
Americium is alkaline metal element with the symbol Am and atomic number 95. It is above uranium in the periodic table and is referred to as a transuranic element. Silvery in color, Americium is a soft radioactive metal. It was first synthesized in 1944 by Glenn T. Seaborg at the University of California, Berkeley. The name was taken from America.
Cobalt is a chemical element with the symbol Co and the atomic number 27. It readily forms compounds with other elements and compounds. When it is extracted from naturally occurring compounds via reductive smelting, it is a hard, shiny, sliver-gray metal.
Plutonium is a silvery-grey radioactive actinide metal with the symbol Pu and the atomic number of 94. Plutonium was first synthesized in 1940 by Glenn Seaborg an Edwin McMillan at the University of California by bombarding U-238 with deuterons which are nuclei of deuterium containing a neutron and a proton. Following its synthesis, plutonium-244 was discovered in minute quantities in the natural environment.
