| Noun | 1. | chemical element - any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all mattermatter, substance - that which has mass and occupies space; "an atom is the smallest indivisible unit of matter" atom - (physics and chemistry) the smallest component of an element having the chemical properties of the element allotrope - a structurally different form of an element; "graphite and diamond are allotropes of carbon" transuranic element - any element having an atomic number greater than 92 (which is the atomic number of uranium); all are radioactive metal, metallic element - any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc. nonmetal - a chemical element lacking typical metallic properties transactinide - any of the artificially produced elements with atomic numbers greater than 103 Ar, argon, atomic number 18 - a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere arsenic, As, atomic number 33 - a very poisonous metallic element that has three allotropic forms; arsenic and arsenic compounds are used as herbicides and insecticides and various alloys; found in arsenopyrite and orpiment and realgar astatine, At, atomic number 85 - a highly unstable radioactive element (the heaviest of the halogen series); a decay product of uranium and thorium atomic number 5, boron, B - a trivalent metalloid element; occurs both in a hard black crystal and in the form of a yellow or brown powder atomic number 35, Br, bromine - a nonmetallic largely pentavalent heavy volatile corrosive dark brown liquid element belonging to the halogens; found in sea water atomic number 6, carbon, C - an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds atomic number 17, chlorine, Cl - a common nonmetallic element belonging to the halogens; best known as a heavy yellow irritating toxic gas; used to purify water and as a bleaching agent and disinfectant; occurs naturally only as a salt (as in sea water) atomic number 9, fluorine, F - a nonmetallic univalent element belonging to the halogens; usually a yellow irritating toxic flammable gas; a powerful oxidizing agent; recovered from fluorite or cryolite or fluorapatite atomic number 32, Ge, germanium - a brittle gray crystalline element that is a semiconducting metalloid (resembling silicon) used in transistors; occurs in germanite and argyrodite atomic number 2, He, helium - a very light colorless element that is one of the six inert gasses; the most difficult gas to liquefy; occurs in economically extractable amounts in certain natural gases (as those found in Texas and Kansas) atomic number 1, H, hydrogen - a nonmetallic univalent element that is normally a colorless and odorless highly flammable diatomic gas; the simplest and lightest and most abundant element in the universe atomic number 53, I, iodin, iodine - a nonmetallic element belonging to the halogens; used especially in medicine and photography and in dyes; occurs naturally only in combination in small quantities (as in sea water or rocks) atomic number 101, Md, mendelevium, Mv - a radioactive transuranic element synthesized by bombarding einsteinium with alpha particles (Md is the current symbol for mendelevium but Mv was formerly the symbol) atomic number 10, Ne, neon - a colorless odorless gaseous element that give a red glow in a vacuum tube; one of the six inert gasses; occurs in the air in small amounts atomic number 7, nitrogen, N - a common nonmetallic element that is normally a colorless odorless tasteless inert diatomic gas; constitutes 78 percent of the atmosphere by volume; a constituent of all living tissues atomic number 102, nobelium, No - a radioactive transuranic element synthesized by bombarding curium with carbon ions; 7 isotopes are known | |