#chemical_element__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 matter
supertype: #substance__matter that which has mass and occupies space; "an atom is the smallest indivisible unit of matter"
part: #atom
subtype: #actinoid__actinide__actinon any of a series of radioactive elements with atomic numbers 89 through 103
subtype: #allotrope a structurally different form of an element: "graphite and diamond are allotropes of carbon"
subtype: #transuranic_element__transuranicelement any element having an atomic number greater than 92" (the atomic number of uranium); all are radioactive
subtype: #noble_gas__noblega__inert_gas__inertga any of the chemically inert gaseous elements of the helium group in the periodic table
subtype: #argon__ar__atomic_number_18 a colorless and odorless inert gas; one of the six inert gases; comprises approximately 1% of the earth's atmosphere
subtype: #helium__He__atomic_number_2 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)
subtype: #krypton__Kr a colorless element that is one of the six inert gasses; occurs in trace amounts in air
subtype: #neon__Ne__atomic_number_10 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
subtype: #radon__Rn__atomic_number_86 a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health
subtype: #xenon__Xe__atomic_number_54 a colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amounts
subtype: #rare_earth__rare-earth_element__lanthanoid__lanthanide__lanthanon any element of the lanthanide series (atomic numbers 57 through 71)
subtype: #terbium_metal__terbiummetal a separate group of related lanthanides, including terbium, europium, gadolinium, and sometimes dysprosium
subtype: #metallic_element__metal any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets etc.
subtype: #noble_metal__noblemetal any metal that is resistant to corrosion or oxidation
subtype: #Au__gold__atomic_number_79 a soft yellow malleable ductile (trivalent and univalent) metallic element; occurs mainly as nuggets in rocks and alluvial deposits; does not react with most chemicals but is attacked by chlorine and aqua regia
subtype: #gold_dust the particles and flakes (and sometimes small nuggets) of gold obtained in placer mining
subtype: #green_gold__greengold a gold alloy (at least 14 karat gold with silver or silver and cadmium) that has a green appearance
subtype: #guinea_gold 22-karat gold from which guinea coins were made
subtype: #platinum__Pt__atomic_number_78 a heavy precious metallic element; gray-white and resistant to corroding; occurs in some nickel and copper ores and is also found native in some deposits
subtype: #Ag__silver__atomic_number_47 a soft white precious univalent metallic element having the highest electrical and thermal conductivity of any metal; occurs in argentite and in free form; used in coins and jewelry and tableware and photography
subtype: #coin_silver a silver of the degree of purity established for making legal silver coins
subtype: #aluminum__aluminium__Al__atomic_number_13 a silvery ductile metallic element found primarily in bauxite
subtype: #potassium_alum__potassiumalum__alum__potash_alum a white crystalline double sulfate of aluminum: the potassium double sulfate of aluminum
subtype: #ammonium_alum__alum__ammonia_alum__ammoniaalum a white crystalline double sulfate of aluminum: the ammonium double sulfate of aluminum
subtype: #americium__Am__atomic_number_95 a radioactive transuranic metallic element; discovered by bombarding uranium with helium atoms
subtype: #antimony__Sb__atomic_number_51 a metallic element having four allotropic forms; used in a wide variety of alloys; found in stibnite
subtype: #barium__Ba__atomic_number_56 a soft silvery metallic element of the alkali earth group; found in barite
subtype: #baryta any of several compounds of barium
subtype: #barium_hydroxide white poisonous crystals; made by dissolving barium oxide in water
subtype: #barium_monoxide__barium_oxide__barium_protoxide an oxide of barium; a whitish toxic powder
subtype: #barium_dioxide__barium_peroxide a white toxic powder obtained by heating barium oxide in air
subtype: #berkelium__Bk__atomic_number_97 a radioactive transuranic element; discovered by bombarding americium with helium
subtype: #beryllium__be__glucinium__atomicnumber4 a light strong brittle gray toxic bivalent metallic element
subtype: #bismuth__Bi__atomic_number_83 a heavy brittle diamagnetic trivalent metallic element (resembles arsenic and antimony chemically); usually recovered as a by-product from ores of other metals
subtype: #cadmium__Cd__atomic_number_48 a soft bluish-white ductile malleable toxic bivalent metallic element; occurs in association with zinc ores
subtype: #calcium__Ca__atomic_number_20 a white metallic element that burns with a brilliant light; the fifth most abundant element in the earth's crust; an important component of most plants and animals
subtype: #californium__Cf__atomic_number_98 a radioactive transuranic element; discovered by bombarding curium with alpha particles
subtype: #cerium__Ce__atomic_number_58 a ductile gray metallic element of the lanthanide series; used in lighter flints; the most abundant of the rare-earth group
subtype: #cesium__caesium__Cs__atomic_number_55 a soft silver-white ductile metallic element (liquid at normal temperatures); the most electropositive and alkaline metal
subtype: #cesium_137 a radioactive isotope of cesium used in radiation therapy
subtype: #chromium__Cr__atomic_number_24 a hard brittle blue-white multivalent metallic element; resistant to corrosion and tarnishing
subtype: #chrome another word for chromium when it is used in dyes or pigments
subtype: #cobalt__Co__atomic_number_27 a hard ferromagnetic silver-white bivalent or trivalent metallic element; a trace element in plant and animal nutrition
subtype: #cobalt_60 a radioactive isotope of cobalt with mass number 60; a source of exceptionally intense gamma rays; used in radiation therapy
subtype: #Cu__copper__atomic_number_29 a ductile malleable reddish-brown corrosion-resistant diamagnetic metallic element; occurs in various minerals but is the only metal that occurs abundantly in large masses; used as an electrical and thermal conductor
subtype: #blister_copper__blistercopper an impure form of copper having a black blistered surface
subtype: #curium__Cm__atomic_number_96 a radioactive transuranic metallic element; produced by bombarding plutonium with helium nuclei
subtype: #dysprosium__Dy__atomic_number_66 a trivalent metallic element of the rare earth group; forms compounds that are highly magnetic
subtype: #einsteinium__Es__E__atomic_number_99 a radioactive transuranic element produced by bombarding plutonium with neutrons
subtype: #erbium__Er__atomic_number_68 a trivalent metallic element of the rare earth group; occurs with yttrium
subtype: #europium__Eu__atomic_number_63 a bivalent and trivalent metallic element of the rare earth group
subtype: #fermium__Fm__atomic_number_100 a radioactive transuranic metallic element produced by bombarding plutonium with neutrons
subtype: #francium__Fr__atomic_number_87 a radioactive element of the alkali-metal group discovered as a disintegration product of actinium
subtype: #gadolinium__Gd__atomic_number_64 a ductile silvery-white ductile ferromagnetic trivalent metallic element of the rare earth group
subtype: #gallium__Ga__atomic_number_31 a rare silvery (usually trivalent) metallic element; brittle at low temperatures but liquid above room temperature; occurs in trace amounts in bauxite and zinc ores
subtype: #hafnium__Hf__atomic_number_72 a gray tetravalent metallic element that resembles zirconium chemically and is found in zirconium minerals; used in filaments for its ready emission of electrons
subtype: #holmium__Ho__atomic_number_67 a trivalent metallic element of the rare earth group; occurs together with yttrium; forms highly magnetic compounds
subtype: #indium__In__atomic_number_49 a rare soft silvery metallic element; occurs in small quantities in sphalerite
subtype: #iridium__Ir__atomic_number_77 a heavy brittle metallic element of the platinum group; used in alloys; occurs in natural alloys with platinum or osmium
subtype: #Fe__iron__atomic_number_26 a heavy ductile magnetic metallic element; is silver-white in pure form but readily rusts; used in construction and tools and armament; plays a role in the transport of oxygen by the blood
subtype: #alpha_iron__alphairon a magnetic allotrope of iron; stable below 906 degrees centigrade
subtype: #beta_iron an allotrope of iron that is the same as alpha iron except that it is nonmagnetic; stable between 768 and 906 degrees centigrade
subtype: #gamma_iron__gammairon a nonmagnetic allotrope of iron that is the basis of austenite; stable between 906 and 1403 degrees centigrade
subtype: #delta_iron__deltairon an allotrope of iron that is stable between 1403 degrees centigrade and the melting point (= 1532 degrees)
subtype: #ingot_iron__ingotiron iron of high purity
subtype: #cast_iron an alloy of iron containing so much carbon that it is brittle and so cannot be wrought but must be shaped by casting
subtype: #alloy_iron__alloyiron__alloycastiron cast iron containing alloying elements (usually nickel or chromium or copper or molybdenum) to increase the strength or facilitate heat treatment
subtype: #Ni-hard_iron__Ni-hard cast iron to which nickel has been added to make it resist abrasion
subtype: #Ni-resist_iron__Ni-resist cast iron consisting of graphite in a matrix of austenite
subtype: #pot_metal.cast_iron__potmetal cast iron used for making cooking wares
subtype: #wrought_iron__wroughtiron iron having a low carbon content that is tough and malleable and so can be forged and welded
subtype: #Swedish_iron wrought iron of high purity made in Sweden
subtype: #galvanized_iron iron that is coated with zinc to protect it from rust
subtype: #pig_iron__pigiron crude iron tapped from a blast furnace
subtype: #basic_iron__basiciron pig iron containing a high percentage of phosphorus; used in making steel by a process that removes the phosphorus
subtype: #cinder_pig pig iron containing a substantial proportion of slag
subtype: #mine_pig pig iron made entirely from ore
subtype: #spiegeleisen__spiegel__spiegel_iron__spiegeliron pig iron containing manganese; used as a deoxidizing agent and to raise the manganese content in making steel
subtype: #scrap_iron__scrapiron iron to be melted again and reworked
subtype: #structural_iron iron that has been cast or worked in structural shapes
subtype: #lanthanum__La__atomic_number_57 a white soft metallic element that tarnishes readily; occurs in rare earth minerals and is usually classified as a rare earth
subtype: #Pb__lead__atomic_number_82 a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull gray; "the children were playing with lead soldiers"
subtype: #hard_lead unrefined lead that is hard because of the impurities it contains
subtype: #antimonial_lead__hard_lead a lead alloy that contains about 5% antimony
subtype: #grid_metal a kind of hard lead that is used for grids in storage batteries
subtype: #pig_lead__piglead lead that is cast in pigs
subtype: #lithium__Li__atomic_number_3 a soft silver-white univalent element of the alkali metal group; the lightest metal known; occurs in several minerals
subtype: #lutetium__lutecium__Lu__atomic_number_71 a trivalent metallic element of the rare earth group; usually occurs in association with yttrium
subtype: #magnesium__Mg__atomic_number_12 a light silver-white ductile bivalent metallic element; in pure form it burns with brilliant white flame; occurs naturally only in combination (as in magnesite and dolomite and carnallite and spinel and olivine)
subtype: #manganese__Mn__atomic_number_25 a hard brittle gray polyvalent metallic element that resembles iron but is not magnetic; used in making steel; occurs in many minerals
subtype: #quicksilver__hydrargyrum__hg__atomic_number_80 a heavy silvery toxic univalent and bivalent metallic element; the only metal that is liquid at ordinary temperatures
subtype: #molybdenum__Mo__atomic_number_42 a polyvalent metallic element that resembles chromium and tungsten in its properties; used to strengthen and harden steel
subtype: #neodymium__Nd__atomic_number_60 a yellow trivalent metallic element of the rare earth group; occurs in monazite and bastnasite in association with cerium and lanthanum and praseodymium
subtype: #neptunium__Np__atomic_number_93 a radioactive transuranic metallic element; found in trace amounts in uranium ores; a by-product of the production of plutonium
subtype: #Ni__nickel__atomic_number_28 a hard malleable ductile silvery metallic element that is resistant to corrosion; used in alloys; occurs in pentlandite and smaltite and garnierite and millerite
subtype: #niobium__Nb__atomic_number_41 a soft gray ductile metallic element used in alloys; occurs in niobite; formerly called columbium
subtype: #columbium a former name for niobium
subtype: #osmium__Os__atomic_number_76 a hard brittle blue-gray or blue-black metallic element that is one of the platinum metals; the heaviest metal known
subtype: #palladium__Pd__atomic_number_46 a sliver-white metallic element of the platinum group that resembles platinum; occurs in some copper and nickel ores; does not tarnish at ordinary temperatures and is used (alloyed with gold) in jewelry
subtype: #polonium__Po__atomic_number_84 a radioactive metallic element that is similar to tellurium and bismuth; occurs in uranium ores but can be produced by bombarding bismuth with neutrons in a nuclear reactor
subtype: #potassium__K__atomic_number_19 a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite
subtype: #praseodymium__Pr__atomic_number_59 a soft yellowish-white trivalent metallic element of the rare earth group; can be recovered from bastnasite or monazite by an ion-exchange process
subtype: #promethium__Pm__atomic_number_61 a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium
subtype: #protactinium__protoactinium__Pa__atomic_number_91 a short-lived radioactive metallic element formed from uranium and disintegrating into actinium and then into lead
subtype: #radium__Ra__atomic_number_88 an intensely radioactive metallic element that occurs in minute amounts in uranium ores
subtype: #rhenium__re__atomic_number_75 a rare heavy polyvalent metallic element that resembles manganese chemically and is used in some alloys; is obtained as a by-product in refining molybdenum
subtype: #rhodium__Rh__atomic_number_45 a white hard metallic element that is one of the platinum group and is found in platinum ores; used in alloys with platinum
subtype: #rubidium__Rb__atomic_number_37 a soft silvery metallic element of the alkali metal group; burns in air and reacts violently in water; occurs in carnallite and lepidolite and pollucite
subtype: #ruthenium__Ru__atomic_number_44 a rare polyvalent metallic element of the platinum group; it is found associated with platinum
subtype: #samarium__Sm__atomic_number_62 a gray lustrous metallic element of the rare earth group; is used in special alloys; occurs in monazite and bastnasite
subtype: #scandium__Sc__atomic_number_21 a white trivalent metallic element; sometimes classified in the rare earth group; occurs in the Scandinavian mineral thortveitite
subtype: #sodium__Na__atomic_number_11 a silvery soft waxy metallic element of the alkali metal group; occurs abundantly in natural compounds (especially in salt water); burns with a yellow flame and reacts violently in water; occurs in sea water and in the mineral halite (rock salt)
subtype: #strontium__Sr__atomic_number_38 a soft silver-white or yellowish metallic element of the alkali metal group; turns yellow in air; occurs in celestite and strontianite
subtype: #strontium_90__strontium90 a radioactive isotope of strontium (with the mass number 90) that is present in the fallout from nuclear explosions; can be assimilated like calcium into bones
subtype: #tantalum__Ta__atomic_number_73 a hard gray lustrous metallic element that is highly corrosion-resistant; occurs in niobite and fergusonite and tantalite
subtype: #technetium__Tc__atomic_number_43 a crystalline metallic element not found in nature; occurs as one of the fission products of uranium
subtype: #terbium__Tb__atomic_number_65 a metallic element of the rare earth group; used in lasers; occurs in apatite and monazite and xenotime and ytterbite
subtype: #thallium__Tl__atomic_number_81 a soft gray malleable metallic element that resembles tin but discolors on exposure to air; it is highly toxic and is used in rodent and insect poisons; occurs in zinc blende and some iron ores
subtype: #thorium__Th__atomic_number_90 a soft silvery-white tetravalent radioactive metallic element; isotope 232 is used as a power source in nuclear reactors; occurs in thorite and in monazite sands
subtype: #thorium-228__thorium228__radiothorium radioactive isotope of thorium with mass number 228
subtype: #thulium__Tm__atomic_number_69 a soft silvery metallic element of the rare earth group; isotope 170 emits X-rays and is used in small portable X-ray machines; it occurs in monazite and apatite and xenotime
subtype: #Sn__tin__atomic_number_50 a silvery malleable metallic element that resists corrosion; used in many alloys and to coat other metals to prevent corrosion; obtained chiefly from cassiterite where it occurs as tin oxide
subtype: #titanium__Ti__atomic_number_22 a light strong gray lustrous corrosion-resistant metallic element used in strong light-weight alloys (as for airplane parts); the main sources are rutile and ilmenite
subtype: #tungsten__wolfram__W__atomic_number_74 a heavy gray-white metallic element; the pure form is used mainly in electrical applications; it is found in several ores including wolframite and scheelite
subtype: #uranium__U__atomic_number_92 a heavy toxic silvery-white radioactive metallic element; occurs in many isotopes; used for nuclear fuels and nuclear weapons
subtype: #uranium_235__uranium235 a uranium isotope with mass number 235; capable of sustaining chain reactions
subtype: #uranium_238 the commonest isotope of uranium; it is not fissionable but when irradiated with neutrons it produces fissionable plutonium 239
subtype: #vanadium__V__atomic_number_23 a soft silvery white toxic metallic element used in steel alloys; it occurs in several complex minerals including carnotite and vanadinite
subtype: #ytterbium__Yb__atomic_number_70 a soft silvery metallic element; a rare earth of the lanthanide series; it occurs in gadolinite and monazite and xenotime
subtype: #yttrium__Y__atomic_number_39 a silvery metallic element that is common in rare-earth minerals; used in magnesium and aluminum alloys
subtype: #zinc__Zn__atomic_number_30 a bluish-white lustrous metallic element; brittle at ordinary temperatures but malleable when heated; used in a wide variety of alloys and in galvanizing iron; it occurs as zinc sulphide in zinc blende
subtype: #zirconium__Zr__atomic_number_40 a lustrous gray strong metallic element resembling titanium; it is used in nuclear reactors as a neutron absorber; it occurs in baddeleyite but is obtained chiefly from zircon
subtype: #alkali_metal__alkaline_metal any of the monovalent metals of group I of the periodic table (lithium or sodium or potassium or rubidium or cesium or francium); "the hydroxides of the alkali metals are strongly alkaline"
subtype: #alkaline-earth_metal__alkaline_earth any of the bivalent metals of group II of the periodic table (calcium or strontium or barium or magnesium or beryllium)
subtype: #nonmetal a chemical element lacking typical metallic properties
subtype: #transactinide any of the artificially produced elements with atomic numbers greater than 103
subtype: #actinium__Ac__atomic_number_89 a radioactive element of the actinide series; found in uranium ores
subtype: #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
subtype: #astatine__At__atomic_number_85 a highly unstable radioactive element (the heaviest of the halogen series); a decay product of uranium and thorium
subtype: #boron__b__atomicnumber5 a trivalent metalloid element; occurs both in a hard black crystal and in the form of a yellow or brown powder
subtype: #bromine__Br__atomic_number_35 a nonmetallic largely pentavalent heavy volatile corrosive dark brown liquid element belonging to the halogens; found in sea water
subtype: #carbon__C__atomic_number_6 an abundant nonmetallic tetravalent element occurring in three allotropic forms: amorphous carbon and graphite and diamond; occurs in all organic compounds
subtype: #fullerene a form of carbon having a large spheroidal molecule consisting of an empty cage of sixty or more carbon atoms
subtype: #buckminsterfullerene__buckyball the first known example of a fullerene
subtype: #radiocarbon__carbon14 a radioactive isotope of carbon
subtype: #wood_coal__charcoal a carbonaceous material obtained by heating wood or other organic matter in the absence of air
subtype: #carbon_black__lampblack__soot__smut a black colloidal substance consisting wholly or principally of amorphous carbon and used to make pigments and ink
subtype: #activated_carbon__activatedcarbon__activated_charcoal__activatedcharcoal powdered or granular carbon used for purifying by adsorption; given orally (as a slurry) it is an antidote for some kinds of poisons
subtype: #graphite__black_lead__blacklead__plumbago used as a lubricant and as a moderator in nuclear reactors
subtype: #pencil_lead__lead mixture of graphite with clay in different degrees of hardness; the marking substance in a pencil
subtype: #adamant__diamond very hard native crystalline carbon valued as a gem
subtype: #black_diamond__blackdiamond__carbonado an inferior dark diamond used in industry for drilling and polishing
subtype: #chlorine__Cl__atomic_number_17 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)
subtype: #radiochlorine a radioactive isotope of chlorine
subtype: #fluorine__F__atomic_number_9__atomicnumber9 a nonmetallic univalent element; usually a yellow irritating toxic flammable gas; a powerful oxidizing agent; recovered from fluorite or cryolite or fluorapatite
subtype: #germanium__Ge__atomic_number_32 a brittle gray crystalline element that is a semiconducting metalloid (resembling silicon) used in transistors; occurs in germanite and argyrodite
subtype: #helium__He__atomic_number_2 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)
subtype: #hydrogen__H__atomic_number_1__atomicnumber1 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
subtype: #tritium a radioactive isotope of hydrogen; atoms of tritium have three times the mass of ordinary hydrogen atoms
subtype: #iodine__iodin__I__atomic_number_53 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)
subtype: #iodine-131 heavy radioactive isotope of iodine with a half-life of 8 days; used in a sodium salt to diagnose thyroid disease and to treat goiter
subtype: #iodine-125 light radioactive isotope of iodine with a half-life of 60 days; used as a tracer in thyroid studies and as a treatment for hyperthyroidism
subtype: #krypton__Kr a colorless element that is one of the six inert gasses; occurs in trace amounts in air
subtype: #lawrencium__Lw__atomic_number_103 a radioactive transuranic element synthesized from californium
subtype: #mendelevium__Md__Mv__atomic_number_101 a radioactive transuranic element synthesized by bombarding einsteinium with alpha particles (Md is the current symbol for mendelevium; Mv was formerly the symbol)
subtype: #neon__Ne__atomic_number_10 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
subtype: #nitrogen__N__atomic_number_7 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
subtype: #azote an obsolete name for nitrogen
subtype: #liquid_nitrogen nitrogen in a liquid state
subtype: #nobelium__No__atomic_number_102 a radioactive transuranic element synthesized by bombarding curium with carbon ions; 7 isotopes are known
subtype: #oxygen__O__atomic_number_8 a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust
subtype: #liquid_oxygen__LOX a bluish transparent magnetic liquid obtained by compressing gaseous oxygen; used as an oxidizer in rocket propellants
subtype: #phosphorus__P__atomic_number_15 a multivalent nonmetallic element of the nitrogen family that occurs commonly in inorganic phosphate rocks and as organic phosphates in all living cells; is highly reactive and occurs in several allotropic forms
subtype: #plutonium__Pu__atomic_number_94 a radioactive transuranic element that is similar to uranium; found in minute quantities in uranium ores but is usually synthesized in nuclear reactors; 13 isotopes are known with the most important being plutonium 239
subtype: #plutonium_239__plutonium239 a highly fissionable isotope of plutonium that is used in atomic weapons and as a reactor fuel; produced by irradiating uranium 238 with slow electrons
subtype: #radon__Rn__atomic_number_86 a radioactive gaseous element formed by the disintegration of radium; the heaviest of the inert gasses; occurs naturally (especially in areas over granite) and is considered a hazard to health
subtype: #rutherfordium__Rf__kurchatovium__Ku__unnilquadium__Unq__element_104__element104__atomic_number_104 a radioactive transuranic element which has been synthesized
subtype: #selenium__Se__atomic_number_34 a toxic nonmetallic element related to sulfur and tellurium; occurs in several allotropic forms; a stable gray metallike allotrope conducts electricity better in the light than in the dark and is used in photocells; occurs in sulfide ores (as pyrite)
subtype: #silicon__Si__atomic_number_14 a tetravalent nonmetallic element; next to oxygen it is the most abundant element in the earth's crust; occurs in clay and feldspar and granite and quartz and sand; used as a semiconductor in transistors
subtype: #sulfur__S__sulphur__atomic_number_16 an abundant tasteless odorless multivalent nonmetallic element; best known in yellow crystals; occurs in many sulphide and sulphate minerals and even in native form (especially in volcanic regions)
subtype: #brimstone__native_sulfur an old name for sulfur
subtype: #tellurium__Te__atomic_number_52 a brittle silver-white metalloid element that is related to selenium and sulfur; it is used in alloys and as a semiconductor; occurs mainly as tellurides in ores of copper and nickel and silver and gold
subtype: #unnilhexium__Unh__element_106__element106__atomic_number_106 a transuranic element
subtype: #unnilquintium__unnilpentium__Unp__hahnium__element105__atomic_number_105 a transuranic element that has not been found in nature
subtype: #unnilseptium__Uns__element_107__element107__atomic_number_107 a transuranic element that has not been found in nature
subtype: #xenon__Xe__atomic_number_54 a colorless odorless inert gaseous element occurring in the earth's atmosphere in trace amounts
subtype: #halogen any of the chemical elements fluorine or chlorine or bromine or iodine or astatine
subtype: #trace_element__traceelement an element that occurs at very small quantities in the body but is nonetheless important for many biological processes
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