Calcium Perrhenate

See more Calcium products. Calcium (atomic symbol: Ca, atomic number: 20) is a Block S, Group 2, Period 4 element with an atomic weight of 40.078. The number of electrons in each of Calcium's shells is [2, 8, 8, 2] and its electron configuration is [Ar]4s². The calcium atom has a radius of 197 pm and a Van der Waals radius of 231 pm. Calcium was discovered and first isolated by Sir Humphrey Davy in 1808. It is the fifth most abundant element in the earth's crust and can be found in minerals such as dolomite, gypsum, plagioclases, amphiboles, pyroxenes and garnets. In its elemental form, calcium has a dull gray-silver appearance. Calcium is a reactive, soft metal that is a member of the alkaline earth elements. It frequently serves as an alloying agent for other metals like aluminum and beryllium, and industrial materials like cement and mortar are composed of calcium compounds like calcium carbonate. It is also an biologically essential substance found in teeth, bones, and shells. The name "calcium" originates from the Latin word "calics," meaning lime.

See more Rhenium products. Rhenium (atomic symbol: Re, atomic number: 75) is a Block D, Group 7, Period 6 element with an atomic weight of 186.207. The number of electrons in each of rhenium's shells is 2, 8, 18, 32, 13, 2 and its electron configuration is [Xe] 4f¹⁴ 5d⁵ 6s². The rhenium atom has a radius of 137 pm and a Van der Waals radius of 217 pm. Rhenium was discovered and first isolated by Masataka Ogawa in 1908. In its elemental form, rhenium has a silvery-white appearance. Rhenium is the fourth densest element exceeded only by platinum, iridium, and osmium. Rhenium's high melting point is exceeded only by those of tungsten and carbon. Rhenium is found in small amounts in gadolinite and molybdenite. It is usually extracted from the flue dusts of molybdenum smelters. The name Rhenium originates from the Latin word 'Rhenus' meaning "Rhine" after the place of discovery.