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+abstract elements = open Merge in {

+

+

+

+

+--  Silvery radioactive metallic element, belongs to 

+-- group 3 of the periodic table. The most stable isotope, Ac_227, has a 

+-- half_life of 217 years. Ac_228 (half_life of 6.13 hours) also occurs in 

+-- nature. There are 22 other artificial isotopes, all radioactive and 

+-- having very short half_lives. Chemistry similar to lanthanum. Used as a 

+-- source of alpha particles. Discovered by A. Debierne in 1899.

+fun Actinium : Class ;

+fun Actinium_Class : SubClass Actinium ElementalSubstance ;

+

+-- Silvery_white lustrous metallic element of group 

+-- 3 of the periodic table. Highly reactive but protected by a thin 

+-- transparent layer of the oxide which quickly forms in air. There are many 

+-- alloys of aluminum, as well as a good number of industrial uses. Makes up 

+-- 8.1 percent of the Earth's crust, by weight. Isolated in 1825 by H.C. 

+-- Oersted.

+fun Aluminum : Class ;

+fun Aluminum_Class : SubClass Aluminum ElementalSubstance ;

+

+-- Radioactive metallic transuranic element, 

+-- belongs to the actinoids. Ten known isotopes. Am_243 is the most stable 

+-- isotope, with a half_life of 7.95*10^3 years. Discovered by Glenn T. 

+-- Seaborg and associates in 1945, it was obtained by bombarding 

+-- {uranium}_238 with alpha particles.

+fun Americium : Class ;

+fun Americium_Class : SubClass Americium ElementalSubstance ;

+

+-- Element of group 15. Multiple allotropic forms. 

+-- The stable form of antimony is a blue_white metal. Yellow and black 

+-- antimony are unstable non_metals. Used in flame_proofing, paints, 

+-- ceramics, enamels, and rubber. Attacked by oxidizing acids and halogens. 

+-- First reported by Tholden in 1450.

+fun Antimony : Class ;

+fun Antimony_Class : SubClass Antimony ElementalSubstance ;

+

+-- Monatomic noble gas. Makes up 0.93 percent of the 

+-- air. Colourless, odorless. Is inert and has no true compounds. Lord 

+-- Rayleigh and Sir william Ramsey identified argon in 1894.

+fun Argon : Class ;

+fun Argon_Class : SubClass Argon ElementalSubstance ;

+

+-- Metalloid element of group 15. There are three 

+-- allotropes, yellow, black, and grey. Reacts with halogens, concentrated 

+-- oxidizing acids and hot alkalis. Albertus Magnus is believed to have been 

+-- the first to isolate the element in 1250.

+fun Arsenic : Class ;

+fun Arsenic_Class : SubClass Arsenic ElementalSubstance ;

+

+-- Radioactive halogen element. Occurs naturally 

+-- from uranium and thorium decay. At least 20 known isotopes. At_210, the 

+-- most stable, has a half_life of 8.3 hours. Synthesized by nuclear 

+-- bombardment in 1940 by D.R. Corson, K.R. MacKenzie and E. Segre at the 

+-- University of California.

+fun Astatine : Class ;

+fun Astatine_Class : SubClass Astatine ElementalSubstance ;

+

+-- Silvery_white reactive element, belonging to group 

+-- 2 of the periodic table. Soluble barium compounds are extremely 

+-- poisonous. Identified in 1774 by Karl Scheele and extracted in 1808 by 

+-- Humphry Davy.

+fun Barium : Class ;

+fun Barium_Class : SubClass Barium ElementalSubstance ;

+

+-- Radioactive metallic transuranic element. 

+-- Belongs to actinoid series. Eight known isotopes, the most common Bk_247, 

+-- has a half_life of 1.4*10^3 years. First produced by Glenn T. Seaborg 

+-- and associates in 1949 by bombarding americium_241 with alpha 

+-- particles.

+fun Berkelium : Class ;

+fun Berkelium_Class : SubClass Berkelium ElementalSubstance ;

+

+-- Grey metallic element of group 2 of the periodic 

+-- table. Is toxic and can cause severe lung diseases and dermatitis. Shows 

+-- high covalent character. It was isolated independently by F. Wohler and 

+-- A.A. Bussy in 1828.

+fun Beryllium : Class ;

+fun Beryllium_Class : SubClass Beryllium ElementalSubstance ;

+

+-- White crystalline metal with a pink tinge, belongs 

+-- to group 15. Most diamagnetic of all metals and has the lowest thermal 

+-- conductivity of all the elements except mercury. Lead_free bismuth 

+-- compounds are used in cosmetics and medical procedures. Burns in the air 

+-- and produces a blue flame. In 1753, C.G. Junine first demonstrated that 

+-- it was different from lead.

+fun Bismuth : Class ;

+fun Bismuth_Class : SubClass Bismuth ElementalSubstance ;

+

+-- An element of group 13 of the periodic table. There 

+-- are two allotropes, amorphous boron is a brown power, but metallic boron 

+-- is black. The metallic form is hard (9.3 on Mohs' scale) and a bad 

+-- conductor in room temperatures. It is never found free in nature. 

+-- Boron_10 is used in nuclear reactor control rods and shields. It was 

+-- discovered in 1808 by Sir Humphry Davy and by J.L. Gay_Lussac and L.J. 

+-- Thenard.

+fun Boron : Class ;

+fun Boron_Class : SubClass Boron ElementalSubstance ;

+

+-- Halogen element. Red volatile liquid at room 

+-- temperature. Its reactivity is somewhere between chlorine and iodine. 

+-- Harmful to human tissue in a liquid state, the vapour irritates eyes and 

+-- throat. Discovered in 1826 by Antoine Balard.

+fun Bromine : Class ;

+fun Bromine_Class : SubClass Bromine ElementalSubstance ;

+

+-- Soft bluish metal belonging to group 12 of the 

+-- periodic table. Extremely toxic even in low concentrations. Chemically 

+-- similar to zinc, but lends itself to more complex compounds. Discovered 

+-- in 1817 by F. Stromeyer.

+fun Cadmium : Class ;

+fun Cadmium_Class : SubClass Cadmium ElementalSubstance ;

+

+-- Soft silvery_white metallic element belonging to 

+-- group 1 of the periodic table. One of the three metals which are liquid 

+-- at room temperature. Cs_133 is the natural, and only stable, isotope. 

+-- Fifteen other radioisotopes exist. Caesium reacts explosively with cold 

+-- water, and ice at temperatures above 157K. Caesium hydroxide is the 

+-- strongest base known. Caesium is the most electropositive, most alkaline 

+-- and has the least ionization potential of all the elements. Known uses 

+-- include the basis of atomic clocks, catalyst for the hydrogenation of some 

+-- organic compounds, and in photoelectric cells. Caesium was discovered by 

+-- Gustav Kirchoff and Robert Bunsen in Germany in 1860 spectroscopically. 

+-- Its identification was based upon the bright blue lines in its spectrum. 

+-- The name comes from the latin word caesius, which means sky blue. Caesium 

+-- should be considered highly toxic. Some of the radioisotopes are even 

+-- more toxic.

+fun Caesium : Class ;

+fun Caesium_Class : SubClass Caesium ElementalSubstance ;

+

+-- Soft grey metallic element belonging to group 2 of 

+-- the periodic table. Used a reducing agent in the extraction of thorium, 

+-- zirconium and uranium. Essential element for living organisms.

+fun Calcium : Class ;

+fun Calcium_Class : SubClass Calcium ElementalSubstance ;

+

+-- Radioactive metallic transuranic element. 

+-- Belongs to actinoid series. Cf_251 has a half life of about 700 years. 

+-- Nine isotopes are known. Cf_252 is an intense {neutron} source, which 

+-- makes it an intense {neutron} source and gives it a use in {neutron} 

+-- activation analysis and a possible use as a radiation source in medicine. 

+-- First produced by Glenn T. Seaborg and associates in 1950.

+fun Californium : Class ;

+fun Californium_Class : SubClass Californium ElementalSubstance ;

+

+-- Carbon is a member of group 14 of the periodic 

+-- table. It has three allotropic forms of it, diamonds, graphite and 

+-- fullerite. Carbon_14 is commonly used in radioactive dating. Carbon 

+-- occurs in all organic life and is the basis of organic chemistry. Carbon 

+-- has the interesting chemical property of being able to bond with itself, 

+-- and a wide variety of other elements.

+fun Carbon : Class ;

+fun Carbon_Class : SubClass Carbon ElementalSubstance ;

+

+-- Silvery metallic element, belongs to the 

+-- lanthanoids. Four natural isotopes exist, and fifteen radioactive 

+-- isotopes have been identified. Used in some rare_earth alloys. The 

+-- oxidized form is used in the glass industry. Discovered by Martin .H. 

+-- Klaproth in 1803.

+fun Cerium : Class ;

+fun Cerium_Class : SubClass Cerium ElementalSubstance ;

+

+-- Halogen element. Poisonous greenish_yellow gas. 

+-- Occurs widely in nature as sodium chloride in seawater. Reacts directly 

+-- with many elements and compounds, strong oxidizing agent. Discovered by 

+-- Karl Scheele in 1774. Humphrey David confirmed it as an element in 

+-- 1810.

+fun Chlorine : Class ;

+fun Chlorine_Class : SubClass Chlorine ElementalSubstance ;

+

+-- Hard silvery transition element. Used in 

+-- decorative electroplating. Discovered in 1797 by Vauquelin.

+fun Chromium : Class ;

+fun Chromium_Class : SubClass Chromium ElementalSubstance ;

+

+-- Light grey transition element. Some meteorites 

+-- contain small amounts of metallic cobalt. Generally alloyed for use. 

+-- Mammals require small amounts of cobalt salts. Cobalt_60, an artificially 

+-- produced radioactive isotope of Cobalt is an important radioactive tracer 

+-- and cancer_treatment agent. Discovered by G. Brandt in 1737.

+fun Cobalt : Class ;

+fun Cobalt_Class : SubClass Cobalt ElementalSubstance ;

+

+-- Red_brown transition element. Known by the Romans 

+-- as 'cuprum.' Extracted and used for thousands of years. Malleable, 

+-- ductile and an excellent conductor of heat and electricity. When in moist 

+-- conditions, a greenish layer forms on the outside.

+fun Copper : Class ;

+fun Copper_Class : SubClass Copper ElementalSubstance ;

+

+-- Radioactive metallic transuranic element. Belongs 

+-- to actinoid series. Nine known isotopes, Cm_247 has a half_life of 

+-- 1.64*10^7 years. First identified by Glenn T. Seaborg and associates in 

+-- 1944, first produced by L.B. Werner and I. Perlman in 1947 by bombarding 

+-- americium_241 with {neutron}s. Named for Marie Curie.

+fun Curium : Class ;

+fun Curium_Class : SubClass Curium ElementalSubstance ;

+

+-- Metallic with a bright silvery_white lustre. 

+-- Dysprosium belongs to the lanthanoids. It is relatively stable in air at 

+-- room temperatures, it will however dissolve in mineral acids, evolving 

+-- hydrogen. It is found in from rare_earth minerals. There are seven 

+-- natural isotopes of dysprosium, and eight radioisotopes, Dy_154 being the 

+-- most stable with a half_life of 3*10^6 years. Dysprosium is used as a 

+-- neutron absorber in nuclear fission reactions, and in compact disks. It 

+-- was discovered by Paul Emile Lecoq de Boisbaudran in 1886 in France. Its 

+-- name comes from the Greek word dysprositos, which means hard to obtain.

+fun Dysprosium : Class ;

+fun Dysprosium_Class : SubClass Dysprosium ElementalSubstance ;

+

+-- Appearance is unknown, however it is most 

+-- probably metallic and silver or gray in color. Radioactive metallic 

+-- transuranic element belonging to the actinoids. Es_254 has the longest 

+-- half_life of the eleven known isotopes at 270 days. First identified by 

+-- Albert Ghiorso and associates in the debris of the 1952 hydrogen bomb 

+-- explosion. In 1961 the first microgram quantities of Es_232 were 

+-- separated. While einsteinium never exists naturally, if a sufficient 

+-- amount was assembled, it would pose a radiation hazard.

+fun Einsteinium : Class ;

+fun Einsteinium_Class : SubClass Einsteinium ElementalSubstance ;

+

+-- Soft silvery metallic element which belongs to the 

+-- lanthanoids. Six natural isotopes that are stable. Twelve artificial 

+-- isotopes are known. Used in nuclear technology as a neutron absorber. It 

+-- is being investigated for other possible uses. Discovered by Carl G. 

+-- Mosander in 1843.

+fun Erbium : Class ;

+fun Erbium_Class : SubClass Erbium ElementalSubstance ;

+

+-- Soft silvery metallic element belonging to the 

+-- lanthanoids. Eu_151 and Eu_153 are the only two stable isotopes, both of 

+-- which are {neutron} absorbers. Discovered in 1889 by Sir William 

+-- Crookes.

+fun Europium : Class ;

+fun Europium_Class : SubClass Europium ElementalSubstance ;

+

+-- Radioactive metallic transuranic element, belongs 

+-- to the actinoids. Ten known isotopes, most stable is Fm_257 with a 

+-- half_life of 10 days. First identified by Albert Ghiorso and associates 

+-- in the debris of the first hydrogen_bomb explosion in 1952.

+fun Fermium : Class ;

+fun Fermium_Class : SubClass Fermium ElementalSubstance ;

+

+-- A poisonous pale yellow gaseous element belonging 

+-- to group 17 of the periodic table (The halogens). It is the most 

+-- chemically reactive and electronegative element. It is highly dangerous, 

+-- causing severe chemical burns on contact with flesh. Fluorine was 

+-- identified by Scheele in 1771 and first isolated by Moissan in 1886.

+fun Fluorine : Class ;

+fun Fluorine_Class : SubClass Fluorine ElementalSubstance ;

+

+-- Radioactive element, belongs to group 1 of the 

+-- periodic table. Found in uranium and thorium ores. The 22 known isotopes 

+-- are all radioactive, with the most stable being Fr_223. Its existence was 

+-- confirmed in 1939 by Marguerite Perey.

+fun Francium : Class ;

+fun Francium_Class : SubClass Francium ElementalSubstance ;

+

+-- Soft silvery metallic element belonging to the 

+-- lanthanoids. Seven natural, stable isotopes are known in addition to 

+-- eleven artificial isotopes. Gd_155 and Gd_157 and the best neutron 

+-- absorbers of all elements. Gadolinium compounds are used in electronics. 

+-- Discovered by J.C.G Marignac in 1880.

+fun Gadolinium : Class ;

+fun Gadolinium_Class : SubClass Gadolinium ElementalSubstance ;

+

+-- Soft silvery metallic element, belongs to group 13 

+-- of the periodic table. The two stable isotopes are Ga_69 and Ga_71. 

+-- Eight radioactive isotopes are known, all having short half_lives. 

+-- Gallium Arsenide is used as a semiconductor. Corrodes most other metals 

+-- by diffusing into their lattice. First identified by Francois Lecoq de 

+-- Boisbaudran in 1875.

+fun Gallium : Class ;

+fun Gallium_Class : SubClass Gallium ElementalSubstance ;

+

+-- Lustrous hard metalloid element, belongs to 

+-- group 14 of the periodic table. Forms a large number of organometallic 

+-- compounds. Predicted by Mendeleev in 1871, it was actually found in 1886 

+-- by Winkler.

+fun Germanium : Class ;

+fun Germanium_Class : SubClass Germanium ElementalSubstance ;

+

+-- Gold is gold colored. It is the most malleable and 

+-- ductile metal known. There is only one stable isotope of gold, and five 

+-- radioisotopes of gold, Au_195 being the most stable with a half_life of 

+-- 186 days. Gold is used as a monetary standard, in jewelry, dentistry, 

+-- electronics. Au_198 is used in treating cancer and some other medical 

+-- conditions. Gold has been known to exist as far back as 2600 BC. Gold 

+-- comes from the Anglo_Saxon word gold. Its symbol, Au, comes from the 

+-- Latin word aurum, which means gold. Gold is not particularly toxic, 

+-- however it is known to cause damage to the liver and kidneys in some.

+fun Gold : Class ;

+fun Gold_Class : SubClass Gold ElementalSubstance ;

+

+-- Silvery lustrous metallic transition element. 

+-- Used in tungsten alloys in filaments and electrodes, also acts as a 

+-- neutron absorber. First reported by Urbain in 1911, existence was finally 

+-- established in 1923 by D. Coster, G.C. de Hevesy in 1923.

+fun Hafnium : Class ;

+fun Hafnium_Class : SubClass Hafnium ElementalSubstance ;

+

+-- Colourless, odourless gaseous nonmetallic element. 

+-- Belongs to group 18 of the periodic table. Lowest boiling point of all 

+-- elements and can only be solidified under pressure. Chemically inert, no 

+-- known compounds. Discovered in the solar spectrum in 1868 by Lockyer.

+fun Helium : Class ;

+fun Helium_Class : SubClass Helium ElementalSubstance ;

+

+-- Relatively soft and malleable silvery_white 

+-- metallic element, which is stable in dry air at room temperature. It 

+-- oxidizes in moist air and at high temperatures. It belongs to the 

+-- lanthanoids. A rare_earth metal, it is found in the minerals monazite and 

+-- gadolinite. It possesses unusual magnetic properties. One natural 

+-- isotope, Ho_165 exists, six radioisotopes exist, the most stable being 

+-- Ho_163 with a half_life of 4570 years. Holmium is used in some metal 

+-- alloys, it is also said to stimulate the metabolism. Discovered by Per 

+-- Theodor Cleve and J.L. Soret in Switzerland in 1879. The name homium 

+-- comes from the Greek word Holmia which means Sweden. While all holmium 

+-- compounds should be considered highly toxic, initial evidence seems to 

+-- indicate that they do not pose much danger. The metal's dust however, is 

+-- a fire hazard.

+fun Holmium : Class ;

+fun Holmium_Class : SubClass Holmium ElementalSubstance ;

+

+-- Colourless, odourless gaseous chemical element. 

+-- Lightest and most abundant element in the universe. Present in water and 

+-- in all organic compounds. Chemically reacts with most elements. 

+-- Discovered by Henry Cavendish in 1776.

+fun Hydrogen : Class ;

+fun Hydrogen_Class : SubClass Hydrogen ElementalSubstance ;

+

+-- Soft silvery element belonging to group 13 of the 

+-- periodic table. The most common natural isotope is In_115, which has a 

+-- half_life of 6*10^4 years. Five other radioisotopes exist. Discovered in 

+-- 1863 by Reich and Richter.

+fun Indium : Class ;

+fun Indium_Class : SubClass Indium ElementalSubstance ;

+

+-- Dark violet nonmetallic element, belongs to group 

+-- 17 of the periodic table. Insoluble in water. Required as a trace 

+-- element for living organisms. One stable isotope, I_127 exists, in 

+-- addition to fourteen radioactive isotopes. Chemically the least reactive 

+-- of the halogens, and the most electropositive metallic halogen. 

+-- Discovered in 1812 by Courtois.

+fun Iodine : Class ;

+fun Iodine_Class : SubClass Iodine ElementalSubstance ;

+

+-- Very hard and brittle, silvery metallic transition 

+-- element. It has a yellowish cast to it. Salts of iridium are highly 

+-- colored. It is the most corrosion resistant metal known, not attacked by 

+-- any acid, but is attacked by molten salts. There are two natural isotopes 

+-- of iridium, and 4 radioisotopes, the most stable being Ir_192 with a 

+-- half_life of 73.83 days. Ir_192 decays into {platinum}, while the other 

+-- radioisotopes decay into {osmium}. Iridium is used in high temperature 

+-- apparatus, electrical contacts, and as a hardening agent for platinum. 

+-- Discovered in 1803 by Smithson Tennant in England. The name comes from 

+-- the Greek word iris, which means rainbow. Iridium metal is generally 

+-- non_toxic due to its relative unreactivity, but iridium compounds should 

+-- be considered highly toxic.

+fun Iridium : Class ;

+fun Iridium_Class : SubClass Iridium ElementalSubstance ;

+

+-- Silvery malleable and ductile metallic transition 

+-- element. Has nine isotopes and is the fourth most abundant element in the 

+-- earth's crust. Required by living organisms as a trace element (used in 

+-- hemoglobin in humans.) Quite reactive, oxidizes in moist air, displaces 

+-- hydrogen from dilute acids and combines with nonmetallic elements.

+fun Iron : Class ;

+fun Iron_Class : SubClass Iron ElementalSubstance ;

+

+-- Colorless gaseous element, belongs to the noble 

+-- gases. Occurs in the air, 0.0001 percent by volume. It can be extracted 

+-- from liquid air by fractional distillation. Generally not isolated, but 

+-- used with other inert gases in fluorescent lamps. Five natural isotopes, 

+-- and five radioactive isotopes. Kr_85, the most stable radioactive 

+-- isotope, has a half_life of 10.76 years and is produced in fission 

+-- reactors. Practically inert, though known to form compounds with 

+-- {fluorine}.

+fun Krypton : Class ;

+fun Krypton_Class : SubClass Krypton ElementalSubstance ;

+

+-- (From the Greek word lanthanein, to line hidden) 

+-- Silvery metallic element belonging to group 3 of the periodic table and 

+-- oft considered to be one of the lanthanoids. Found in some rare_earth 

+-- minerals. Twenty_five natural isotopes exist. La_139 which is stable, 

+-- and La_138 which has a half_life of 10^10 to 10^15 years. The other 

+-- twenty_three isotopes are radioactive. It resembles the lanthanoids 

+-- chemically. Lanthanum has a low to moderate level of toxicity, and should 

+-- be handled with care. Discovered in 1839 by C.G. Mosander.

+fun Lanthanum : Class ;

+fun Lanthanum_Class : SubClass Lanthanum ElementalSubstance ;

+

+-- Appearance unknown, however it is most likely 

+-- silvery_white or grey and metallic. Lawrencium is a synthetic rare_earth 

+-- metal. There are eight known radioisotopes, the most stable being Lr_262 

+-- with a half_life of 3.6 hours. Due to the short half_life of lawrencium, 

+-- and its radioactivity, there are no known uses for it. Identified by 

+-- Albert Ghiorso in 1961 at Berkeley. It was produced by bombarding 

+-- californium with boron ions. The name is temporary {IUPAC} nomenclature, 

+-- the origin of the name comes from Ernest O. Lawrence, the inventor of the 

+-- cyclotron. If sufficient amounts of lawrencium were produced, it would 

+-- pose a radiation hazard.

+fun Lawrencium : Class ;

+fun Lawrencium_Class : SubClass Lawrencium ElementalSubstance ;

+

+-- Heavy dull grey ductile metallic element, belongs to 

+-- group 14. Used in building construction, lead_place accumulators, bullets 

+-- and shot, and is part of solder, pewter, bearing metals, type metals and 

+-- fusible alloys.

+fun Lead : Class ;

+fun Lead_Class : SubClass Lead ElementalSubstance ;

+

+-- Socket silvery metal. First member of group 1 of 

+-- the periodic table. Lithium salts are used in psychomedicine.

+fun Lithium : Class ;

+fun Lithium_Class : SubClass Lithium ElementalSubstance ;

+

+-- Silvery_white rare_earth metal which is 

+-- relatively stable in air. It happens to be the most expensive rare_earth 

+-- metal. Its found with almost all rare_earth metals, but is very difficult 

+-- to separate from other elements. Least abundant of all natural elements. 

+-- Used in metal alloys, and as a catalyst in various processes. There are 

+-- two natural, stable isotopes, and seven radioisotopes, the most stable 

+-- being Lu_174 with a half_life of 3.3 years. The separation of lutetium 

+-- from {ytterbium} was described by Georges Urbain in 1907. It was 

+-- discovered at approximately the same time by Carl Auer von Welsbach. The 

+-- name comes from the Greek word lutetia which means Paris.

+fun Lutetium : Class ;

+fun Lutetium_Class : SubClass Lutetium ElementalSubstance ;

+

+-- Silvery metallic element belonging to group 2 of 

+-- the periodic table (alkaline_earth metals). It is essential for living 

+-- organisms, and is used in a number of light alloys. Chemically very 

+-- reactive, it forms a protective oxide coating when exposed to air and 

+-- burns with an intense white flame. It also reacts with sulphur, nitrogen 

+-- and the halogens. First isolated by Bussy in 1828.

+fun Magnesium : Class ;

+fun Magnesium_Class : SubClass Magnesium ElementalSubstance ;

+

+-- Grey brittle metallic transition element. 

+-- Rather electropositive, combines with some non_metals when heated. 

+-- Discovered in 1774 by Scheele.

+fun Manganese : Class ;

+fun Manganese_Class : SubClass Manganese ElementalSubstance ;

+

+-- Half_life of approximately 5ms. The creation 

+-- of this element demonstrated that fusion techniques could indeed be used 

+-- to make new, heavy nuclei. Made and identified by physicists of the Heavy 

+-- Ion Research Laboratory, Darmstadt, West Germany in 1982. Named in honor 

+-- of Lise Meitner the Austrian physicist.

+fun Meitnerium : Class ;

+fun Meitnerium_Class : SubClass Meitnerium ElementalSubstance ;

+

+-- Radioactive metallic transuranic element. 

+-- Belongs to the actinoid series. Only known isotope, Md_256 has a 

+-- half_life of 1.3 hours. First identified by Glenn T. Seaborg, Albert 

+-- Ghiorso and associates in 1955. Alternative name {unnilunium} has been 

+-- proposed. Named after the 'inventor' of the periodic table, Dmitri 

+-- Mendeleev.

+fun Mendelevium : Class ;

+fun Mendelevium_Class : SubClass Mendelevium ElementalSubstance ;

+

+-- Heavy silvery liquid metallic element, belongs to 

+-- the zinc group. Used in thermometers, barometers and other scientific 

+-- apparatus. Less reactive than zinc and cadmium, does not displace 

+-- hydrogen from acids. Forms a number of complexes and organomercury 

+-- compounds.

+fun Mercury : Class ;

+fun Mercury_Class : SubClass Mercury ElementalSubstance ;

+

+-- Silvery_white, hard metallic transition 

+-- element. It is chemically unreactive and is not affected by most acids. 

+-- It oxidizes at high temperatures. There are seven natural isotopes, and 

+-- four radioisotopes, Mo_93 being the most stable with a half_life of 3500 

+-- years. Molybdenum is used in almost all high_strength steels, it has 

+-- nuclear applications, and is a catalyst in petroleum refining. Discovered 

+-- in 1778 by Carl Welhelm Scheele of Sweden. Impure metal was prepared in 

+-- 1782 by Peter Jacob Hjelm. The name comes from the Greek word molybdos 

+-- which means lead. Trace amounts of molybdenum are required for all known 

+-- forms of life. All molybdenum compounds should be considered highly 

+-- toxic, and will also cause severe birth defects.

+fun Molybdenum : Class ;

+fun Molybdenum_Class : SubClass Molybdenum ElementalSubstance ;

+

+-- Soft bright silvery metallic element, belongs to 

+-- the lanthanoids. Seven natural isotopes, Nd_144 being the only 

+-- radioactive one with a half_life of 10^10 to 10^15 years. Six artificial 

+-- radioisotopes have been produced. The metal is used in glass works to 

+-- color class a shade of violet_purple and make it dichroic. One of the 

+-- more reactive rare_earth metals, quickly reacts with air. Used in some 

+-- rare_earth alloys. Neodymium is used to color the glass used in welder's 

+-- glasses. Neodymium is also used in very powerful, permanent magnets 

+-- (Nd2Fe14B). Discovered by Carl F. Auer von Welsbach in Austria in 1885 

+-- by separating didymium into its elemental components {praseodymium} and 

+-- neodymium. The name comes from the Greek words 'neos didymos' which means 

+-- 'new twin'. Neodymium should be considered highly toxic, however evidence 

+-- would seem to show that it acts as little more than a skin and eye 

+-- irritant. The dust however, presents a fire and explosion hazard.

+fun Neodymium : Class ;

+fun Neodymium_Class : SubClass Neodymium ElementalSubstance ;

+

+-- Colourless gaseous element of group 18 on the 

+-- periodic table (noble gases). Neon occurs in the atmosphere, and 

+-- comprises 0.0018 percent of the volume of the atmosphere. It has a 

+-- distinct reddish glow when used in discharge tubes and neon based lamps. 

+-- It forms almost no chemical compounds. Neon was discovered in 1898 by Sir 

+-- William Ramsey and M.W. Travers.

+fun Neon : Class ;

+fun Neon_Class : SubClass Neon ElementalSubstance ;

+

+-- Radioactive metallic transuranic element, 

+-- belongs to the actinoids. Np_237, the most stable isotope, has a 

+-- half_life of 2.2*10^6 years and is a by product of nuclear reactors. The 

+-- other known isotopes have mass numbers 229 through 236, and 238 through 

+-- 241. Np_236 has a half_life of 5*10^3 years. First produced by Edwin M. 

+-- McMillan and P.H. Abelson in 1940.

+fun Neptunium : Class ;

+fun Neptunium_Class : SubClass Neptunium ElementalSubstance ;

+

+-- Malleable ductile silvery metallic transition 

+-- element. Discovered by A.F. Cronstedt in 1751.

+fun Nickel : Class ;

+fun Nickel_Class : SubClass Nickel ElementalSubstance ;

+

+-- Soft, ductile grey_blue metallic transition 

+-- element. Used in special steels and in welded joints to increase 

+-- strength. Combines with halogens and oxidizes in air at 200 degrees 

+-- celsius. Discovered by Charles Hatchett in 1801 and isolated by 

+-- Blomstrand in 1864. Called {columbium} originally.

+fun Niobium : Class ;

+fun Niobium_Class : SubClass Niobium ElementalSubstance ;

+

+-- Colourless, gaseous element which belongs to 

+-- group 15 of the periodic table. Constitutes ~78 percent of the atmosphere 

+-- and is an essential part of the ecosystem. Nitrogen for industrial 

+-- purposes is acquired by the fractional distillation of liquid air. 

+-- Chemically inactive, reactive generally only at high temperatures or in 

+-- electrical discharges. It was discovered in 1772 by D. Rutherford.

+fun Nitrogen : Class ;

+fun Nitrogen_Class : SubClass Nitrogen ElementalSubstance ;

+

+-- Radioactive metallic transuranic element, belongs 

+-- to the actinoids. Seven known isotopes exist, the most stable being 

+-- No_254 with a half_life of 255 seconds. First identified with certainty 

+-- by Albert Ghiorso and Glenn T. Seaborg in 1966. {Unnilbium} has been 

+-- proposed as an alternative name.

+fun Nobelium : Class ;

+fun Nobelium_Class : SubClass Nobelium ElementalSubstance ;

+

+-- Hard blue_white metallic transition element. Found 

+-- with platinum and used in some alloys with platinum and iridium.

+fun Osmium : Class ;

+fun Osmium_Class : SubClass Osmium ElementalSubstance ;

+

+-- A colourless, odourless gaseous element belonging 

+-- to group 16 of the periodic table. It is the most abundant element 

+-- present in the earth's crust. It also makes up 20.8 percent of the 

+-- Earth's atmosphere. For industrial purposes, it is separated from liquid 

+-- air by fractional distillation. It is used in high temperature welding, 

+-- and in breathing. It commonly comes in the form of Oxygen, but is found 

+-- as Ozone in the upper atmosphere. It was discovered by Priestley in 

+-- 1774.

+fun Oxygen : Class ;

+fun Oxygen_Class : SubClass Oxygen ElementalSubstance ;

+

+-- Soft white ductile transition element. Found 

+-- with some copper and nickel ores. Does not react with oxygen at normal 

+-- temperatures. Dissolves slowly in hydrochloric acid. Discovered in 1803 

+-- by W.H. Wollaston.

+fun Palladium : Class ;

+fun Palladium_Class : SubClass Palladium ElementalSubstance ;

+

+-- Non_metallic element belonging to group 15 of 

+-- the periodic table. Has a multiple allotropic forms. Essential element 

+-- for living organisms. It was discovered by Brandt in 1669.

+fun Phosphorus : Class ;

+fun Phosphorus_Class : SubClass Phosphorus ElementalSubstance ;

+

+-- Attractive greyish_white metal. When pure, it is 

+-- malleable and ductile. Does not oxidize in air, insoluble in hydrochloric 

+-- and nitric acid. Corroded by halogens, cyandies, sulphur and alkalis. 

+-- {Hydrogen} and {oxygen} react explosively in the presence of platinum. 

+-- There are six stable isotopes and three radioisotopes, the most stable 

+-- being Pt_193 with a half_life of 60 years. Platinum is used in jewelry, 

+-- laboratory equipment, electrical contacts, dentistry, and anti_pollution 

+-- devices in cars. PtCl2(NH3)2 is used to treat some forms of cancer. 

+-- Platinum_{cobalt} alloys have magnetic properties. It is also used in the 

+-- definition of the Standard Hydrogen Electrode. Discovered by Antonio de 

+-- Ulloa in South America in 1735. The name comes from the Spanish word 

+-- platina which means silver. Platinum metal is generally not a health 

+-- concern due to its unreactivity, however platinum compounds should be 

+-- considered highly toxic.

+fun Platinum : Class ;

+fun Platinum_Class : SubClass Platinum ElementalSubstance ;

+

+-- Dense silvery radioactive metallic transuranic 

+-- element, belongs to the actinoids. Pu_244 is the most stable isotope with 

+-- a half_life of 7.6*10^7 years. Thirteen isotopes are known. Pu_239 is 

+-- the most important, it undergoes nuclear fission with slow neutrons and is 

+-- hence important to nuclear weapons and reactors. Plutonium production is 

+-- monitored down to the gram to prevent military misuse. First produced by 

+-- Gleen T. Seaborg, Edwin M. McMillan, J.W. Kennedy and A.C. Wahl in 

+-- 1940.

+fun Plutonium : Class ;

+fun Plutonium_Class : SubClass Plutonium ElementalSubstance ;

+

+-- Rare radioactive metallic element, belongs to 

+-- group 16 of the periodic table. Over 30 known isotopes exist, the most of 

+-- all elements. Po_209 has a half_life of 103 years. Possible uses in 

+-- heating spacecraft. Discovered by Marie Curie in 1898 in a sample of 

+-- pitchblende.

+fun Polonium : Class ;

+fun Polonium_Class : SubClass Polonium ElementalSubstance ;

+

+-- Soft silvery metallic element belonging to group 

+-- 1 of the periodic table (alkali metals). Occurs naturally in seawater and 

+-- a many minerals. Highly reactive, chemically, it resembles sodium in its 

+-- behavior and compounds. Discovered by Sir Humphry Davy in 1807.

+fun Potassium : Class ;

+fun Potassium_Class : SubClass Potassium ElementalSubstance ;

+

+-- Soft silvery metallic element, belongs to the 

+-- lanthanoids. Only natural isotope is Pr_141 which is not radioactive. 

+-- Fourteen radioactive isotopes have been artificially produced. Used in 

+-- rare_earth alloys. Discovered in 1885 by C.A. von Welsbach.

+fun Praseodymium : Class ;

+fun Praseodymium_Class : SubClass Praseodymium ElementalSubstance ;

+

+-- Soft silvery metallic element, belongs to the 

+-- lanthanoids. Pm_147, the only natural isotope, is radioactive and has a 

+-- half_life of 252 years. Eighteen radioisotopes have been produced, but 

+-- all have very short half_lives. Found only in nuclear decay waste. 

+-- Pm_147 is of interest as a beta_decay source, however Pm_146 and Pm_148 

+-- have to be removed from it first, as they generate gamma radiation. 

+-- Discovered by J.A. Marinsky, L.E. Glendenin and C.D. Coryell in 

+-- 1947.

+fun Promethium : Class ;

+fun Promethium_Class : SubClass Promethium ElementalSubstance ;

+

+-- Radioactive metallic element, belongs to the 

+-- actinoids. The most stable isotope, Pa_231 has a half_life of 2.43*10^4 

+-- years. At least 10 other radioactive isotopes are known. No practical 

+-- applications are known. Discovered in 1917 by Lise Meitner and Otto 

+-- Hahn.

+fun Protactinium : Class ;

+fun Protactinium_Class : SubClass Protactinium ElementalSubstance ;

+

+-- Radioactive metallic transuranic element, belongs 

+-- to group 2 of the periodic table. Most stable isotope, Ra_226 has a 

+-- half_life of 1602 years, which decays into radon. Isolated from 

+-- pitchblende in 1898 Marie and Pierre Curie.

+fun Radium : Class ;

+fun Radium_Class : SubClass Radium ElementalSubstance ;

+

+-- Colorless radioactive gaseous element, belongs to 

+-- the noble gases. Of the twenty known isotopes, the most stable is Rn_222 

+-- with a half_life of 3.8 days. Formed by the radioactive decay of 

+-- {Radium}_226. Radon itself decays into {polonium}. Used in radiotherapy. 

+-- As a noble gas, it is effectively inert, though radon fluoride has been 

+-- synthesized. First isolated in 1908 by Ramsey and Gray.

+fun Radon : Class ;

+fun Radon_Class : SubClass Radon ElementalSubstance ;

+

+-- Silvery_white metallic transition element. 

+-- Obtained as a by_product of molybdenum refinement. Rhenium_molybdenum 

+-- alloys are superconducting.

+fun Rhenium : Class ;

+fun Rhenium_Class : SubClass Rhenium ElementalSubstance ;

+

+-- Silvery white metallic transition element. Found 

+-- with platinum and used in some platinum alloys. Not attacked by acids, 

+-- dissolves only in aqua regia. Discovered in 1803 by W.H. Wollaston.

+fun Rhodium : Class ;

+fun Rhodium_Class : SubClass Rhodium ElementalSubstance ;

+

+-- Soft silvery metallic element, belongs to group 1 

+-- of the periodic table. Rb_97, the naturally occurring isotope, is 

+-- radioactive. It is highly reactive, with properties similar to other 

+-- elements in group 1, like igniting spontaneously in air. Discovered 

+-- spectroscopically in 1861 by W. Bunsen and G.R. Kirchoff.

+fun Rubidium : Class ;

+fun Rubidium_Class : SubClass Rubidium ElementalSubstance ;

+

+-- Hard white metallic transition element. Found 

+-- with platinum, used as a catalyst in some platinum alloys. Dissolves in 

+-- fused alkalis, and is not attacked by acids. Reacts with halogens and 

+-- oxygen at high temperatures. Isolated in 1844 by K.K. Klaus.

+fun Ruthenium : Class ;

+fun Ruthenium_Class : SubClass Ruthenium ElementalSubstance ;

+

+-- Soft silvery metallic element, belongs to the 

+-- lanthanoids. Seven natural isotopes, Sm_147 is the only radioisotope, and 

+-- has a half_life of 2.5*10^11 years. Used for making special alloys needed 

+-- in the production of nuclear reactors. Also used as a neutron absorber. 

+-- Small quantities of samarium oxide is used in special optical glasses. 

+-- The largest use of the element is its ferromagnetic alloy which produces 

+-- permanent magnets that are five times stronger than magnets produced by 

+-- any other material. Discovered by Francois Lecoq de Boisbaudran in 

+-- 1879.

+fun Samarium : Class ;

+fun Samarium_Class : SubClass Samarium ElementalSubstance ;

+

+-- Rare soft silvery metallic element belonging to 

+-- group 3 of the periodic table. There are ten isotopes, nine of which are 

+-- radioactive and have short half_lives. Predicted in 1869 by Mendeleev, 

+-- isolated by Nilson in 1879.

+fun Scandium : Class ;

+fun Scandium_Class : SubClass Scandium ElementalSubstance ;

+

+-- Metalloid element, belongs to group 16 of the 

+-- periodic table. Multiple allotropic forms exist. Chemically resembles 

+-- sulphur. Discovered in 1817 by Jons J. Berzelius.

+fun Selenium : Class ;

+fun Selenium_Class : SubClass Selenium ElementalSubstance ;

+

+-- Metalloid element belonging to group 14 of the 

+-- periodic table. It is the second most abundant element in the Earth's 

+-- crust, making up 25.7 percent of it by weight. Chemically less reactive 

+-- than carbon. First identified by Lavoisier in 1787 and first isolated in 

+-- 1823 by Berzelius.

+fun Silicon : Class ;

+fun Silicon_Class : SubClass Silicon ElementalSubstance ;

+

+-- White lustrous soft metallic transition element. 

+-- Found in both its elemental form and in minerals. Used in jewellery, 

+-- tableware and so on. Less reactive than silver, chemically.

+fun Silver : Class ;

+fun Silver_Class : SubClass Silver ElementalSubstance ;

+

+-- Soft silvery reactive element belonging to group 1 

+-- of the periodic table (alkali metals). It is highly reactive, oxidizing 

+-- in air and reacting violently with water, forcing it to be kept under oil. 

+-- It was first isolated by Humphrey Davy in 1807.

+fun Sodium : Class ;

+fun Sodium_Class : SubClass Sodium ElementalSubstance ;

+

+-- Soft yellowish metallic element, belongs to 

+-- group 2 of the periodic table. Highly reactive chemically. Sr_90 is 

+-- present in radioactive fallout and has a half_life of 28 years. 

+-- Discovered in 1798 by Klaproth and Hope, isolated in 1808 by Humphry 

+-- Davy.

+fun Strontium : Class ;

+fun Strontium_Class : SubClass Strontium ElementalSubstance ;

+

+-- Yellow, nonmetallic element belonging to group 16 

+-- of the periodic table. It is an essential element in living organisms, 

+-- needed in the amino acids cysteine and methionine, and hence in many 

+-- proteins. Absorbed by plants from the soil as sulphate ion.

+fun Sulphur : Class ;

+fun Sulphur_Class : SubClass Sulphur ElementalSubstance ;

+

+-- Heavy blue_grey metallic transition element. 

+-- Ta_181 is a stable isotope, and Ta_180 is a radioactive isotope, with a 

+-- half_life in excess of 10^7 years. Used in surgery as it is unreactive. 

+-- Forms a passive oxide layer in air. Identified in 1802 by Ekeberg and 

+-- isolated in 1820 by Jons J. Berzelius.

+fun Tantalum : Class ;

+fun Tantalum_Class : SubClass Tantalum ElementalSubstance ;

+

+-- Radioactive metallic transition element. Can 

+-- be detected in some stars and the fission products of uranium. First made 

+-- by Perrier and Segre by bombarding molybdenum with deutrons, giving them 

+-- Tc_97. Tc_99 is the most stable isotope with a half_life of 2.6*10^6 

+-- years. Sixteen isotopes are known. Organic technetium compounds are used 

+-- in bone imaging. Chemical properties are intermediate between rhenium and 

+-- manganese.

+fun Technetium : Class ;

+fun Technetium_Class : SubClass Technetium ElementalSubstance ;

+

+-- Silvery metalloid element of group 16. Eight 

+-- natural isotopes, nine radioactive isotopes. Used in semiconductors and 

+-- to a degree in some steels. Chemistry is similar to {sulphur}. 

+-- Discovered in 1782 by Franz Miller.

+fun Tellurium : Class ;

+fun Tellurium_Class : SubClass Tellurium ElementalSubstance ;

+

+-- Silvery metallic element belonging to the 

+-- lanthanoids. Tb_159 is the only stable isotope, there are seventeen 

+-- artificial isotopes. Discovered by G.G. Mosander in 1843.

+fun Terbium : Class ;

+fun Terbium_Class : SubClass Terbium ElementalSubstance ;

+

+-- Pure, unreacted thallium appears silvery_white 

+-- and exhibits a metallic lustre. Upon reacting with air, it begins to turn 

+-- bluish_grey and looks like lead. It is very malleable, and can be cut 

+-- with a knife. There are two stable isotopes, and four radioisotopes, 

+-- Tl_204 being the most stable with a half_life of 3.78 years. Thallium 

+-- sulphate was used as a rodenticide. Thallium sulphine's conductivity 

+-- changes with exposure to infrared light, this gives it a use in infrared 

+-- detectors. Discovered by Sir William Crookes via spectroscopy. Its name 

+-- comes from the Greek word thallos, which means green twig. Thallium and 

+-- its compounds are toxic and can cause cancer.

+fun Thallium : Class ;

+fun Thallium_Class : SubClass Thallium ElementalSubstance ;

+

+-- Grey radioactive metallic element. Belongs to 

+-- actinoids. Found in monazite sand in Brazil, India and the US. 

+-- Thorium_232 has a half_life of 1.39x10^10 years. Can be used as a nuclear 

+-- fuel for breeder reactors. Thorium_232 captures slow {neutron}s and 

+-- breeds uranium_233. Discovered by Jons J. Berzelius in 1829.

+fun Thorium : Class ;

+fun Thorium_Class : SubClass Thorium ElementalSubstance ;

+

+-- Soft grey metallic element that belongs to the 

+-- lanthanoids. One natural isotope exists, Tm_169, and seventeen artificial 

+-- isotopes have been produced. No known uses for the element. Discovered 

+-- in 1879 by Per Theodor Cleve.

+fun Thulium : Class ;

+fun Thulium_Class : SubClass Thulium ElementalSubstance ;

+

+-- Silvery malleable metallic element belonging to group 

+-- 14 of the periodic table. Twenty_six isotopes are known, five of which 

+-- are radioactive. Chemically reactive. Combines directly with chlorine 

+-- and oxygen and displaces hydrogen from dilute acids.

+fun Tin : Class ;

+fun Tin_Class : SubClass Tin ElementalSubstance ;

+

+-- White metallic transition element. Occurs in 

+-- numerous minerals. Used in strong, light corrosion_resistant alloys. 

+-- Forms a passive oxide coating when exposed to air. First discovered by 

+-- Gregor in 1789.

+fun Titanium : Class ;

+fun Titanium_Class : SubClass Titanium ElementalSubstance ;

+

+-- White or grey metallic transition element, 

+-- formerly called {wolfram}. Forms a protective oxide in air and can be 

+-- oxidized at high temperature. First isolated by Jose and Fausto de 

+-- Elhuyer in 1783.

+fun Tungsten : Class ;

+fun Tungsten_Class : SubClass Tungsten ElementalSubstance ;

+

+-- Half_life of approximately 10ms. Reported in 

+-- 1994 by German researchers at Darmstadt, Germany.

+fun Unnildecium : Class ;

+fun Unnildecium_Class : SubClass Unnildecium ElementalSubstance ;

+

+-- Half_life of 0.9 +/_ 0.2 s. Discovered by the 

+-- Joint Institute for Nuclear Research at Dubna (U.S.S.R.) in June of 1974. 

+-- Its existence was confirmed by the Lawrence Berkeley Laboratory and 

+-- Livermore National Laboratory in September of 1974.

+fun Unnilhexium : Class ;

+fun Unnilhexium_Class : SubClass Unnilhexium ElementalSubstance ;

+

+-- Radioactive transition metal.

+fun Unniloctium : Class ;

+fun Unniloctium_Class : SubClass Unniloctium ElementalSubstance ;

+

+-- Radioactive transactinide element. Half_life 

+-- of 1.6s. Discovered in 1970 by Berkeley researchers. So far, seven 

+-- isotopes have been discovered.

+fun Unnilpentium : Class ;

+fun Unnilpentium_Class : SubClass Unnilpentium ElementalSubstance ;

+

+-- Radioactive transactinide element. Expected 

+-- to have similar chemical properties to those displayed by hafnium. Rf_260 

+-- was discovered by the Joint Nuclear Research Institute at Dubna (U.S.S.R.) 

+-- in 1964. Researchers at Berkeley discovered Unq_257 and Unq_258 in 

+-- 1964.

+fun Unnilquadium : Class ;

+fun Unnilquadium_Class : SubClass Unnilquadium ElementalSubstance ;

+

+-- Radioactive transition metal. Half_life of 

+-- approximately 1/500 s. Discovered by the Joint Institute for Nuclear 

+-- Research at Dubna (U.S.S.R.) in 1976. Confirmed by West German physicists 

+-- at the Heavy Ion Research Laboratory at Darmstadt.

+fun Unnilseptium : Class ;

+fun Unnilseptium_Class : SubClass Unnilseptium ElementalSubstance ;

+

+-- White radioactive metallic element belonging to 

+-- the actinoids. Three natural isotopes, U_238, U_235 and U_234. 

+-- Uranium_235 is used as the fuel for nuclear reactors and weapons. 

+-- Discovered by Martin H. Klaproth in 1789.

+fun Uranium : Class ;

+fun Uranium_Class : SubClass Uranium ElementalSubstance ;

+

+-- Soft and ductile, bright white metal. Good 

+-- resistance to corrosion by alkalis, sulphuric and hydrochloric acid. It 

+-- oxidizes readily about 933K. There are two naturally occurring isotopes 

+-- of vanadium, and 5 radioisotopes, V_49 having the longest half_life at 337 

+-- days. Vanadium has nuclear applications, the foil is used in cladding 

+-- titanium to steel, and vanadium_gallium tape is used to produce a 

+-- superconductive magnet. Originally discovered by Andres Manuel del Rio of 

+-- Mexico City in 1801. His discovery went unheeded, however, and in 1820, 

+-- Nils Gabriel Sefstron of Sweden rediscovered it. Metallic vanadium was 

+-- isolated by Henry Enfield Roscoe in 1867. The name vanadium comes from 

+-- {Vanadis}, a goddess of Scandinavian mythology. Silvery_white metallic 

+-- transition element. Vanadium is essential to {ascidian}s. Rats and 

+-- chickens are also known to require it. Metal powder is a fire hazard, and 

+-- vanadium compounds should be considered highly toxic. May cause lung 

+-- cancer if inhaled.

+fun Vanadium : Class ;

+fun Vanadium_Class : SubClass Vanadium ElementalSubstance ;

+

+-- Colourless, odourless gas belonging to group 18 on 

+-- the periodic table (the noble gases.) Nine natural isotopes and seven 

+-- radioactive isotopes are known. Xenon was part of the first noble_gas 

+-- compound synthesized. Several others involving Xenon have been found 

+-- since then. Xenon was discovered by Ramsey and Travers in 1898.

+fun Xenon : Class ;

+fun Xenon_Class : SubClass Xenon ElementalSubstance ;

+

+-- Silvery metallic element of the lanthanoids. 

+-- Seven natural isotopes and ten artificial isotopes are known. Used in 

+-- certain steels. Discovered by J.D.G. Marignac in 1878.

+fun Ytterbium : Class ;

+fun Ytterbium_Class : SubClass Ytterbium ElementalSubstance ;

+

+-- Silvery_grey metallic element of group 3 on the 

+-- periodic table. Found in uranium ores. The only natural isotope is Y_89, 

+-- there are 14 other artificial isotopes. Chemically resembles the 

+-- lanthanoids. Stable in the air below 400 degrees, celsius. Discovered in 

+-- 1828 by Friedrich Wohler.

+fun Yttrium : Class ;

+fun Yttrium_Class : SubClass Yttrium ElementalSubstance ;

+

+-- Blue_white metallic element. Occurs in multiple 

+-- compounds naturally. Five stable isotopes are six radioactive isotopes 

+-- have been found. Chemically a reactive metal, combines with oxygen and 

+-- other non_metals, reacts with dilute acids to release hydrogen.

+fun Zinc : Class ;

+fun Zinc_Class : SubClass Zinc ElementalSubstance ;

+

+-- Grey_white metallic transition element. Five 

+-- natural isotopes and six radioactive isotopes are known. Used in nuclear 

+-- reactors for a {neutron} absorber. Discovered in 1789 by Martin Klaproth, 

+-- isolated in 1824 by Berzelius.

+fun Zirconium : Class ;

+fun Zirconium_Class : SubClass Zirconium ElementalSubstance ;

+}
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