actinium	actinium<br/>Symbol: Ac<br/>Atomic number: 89<br/>Atomic weight: (227)<br/>Silvery radioactive metallic element, belongs to group 3 of the periodic<br/>table. The most stable isotope, Ac-227, has a half-life of 217 years.<br/>Ac-228 (half-life of 6.13 hours) also occurs in nature. There are 22 other<br/>artificial isotopes, all radioactive and having very short half-lives.<br/>Chemistry similar to lanthanum. Used as a source of alpha particles.<br/>Discovered by A. Debierne in 1899.<br/>
aluminum	aluminum<br/>Symbol: Al<br/>Atomic number: 13<br/>Atomic weight: 26.9815<br/>Silvery-white lustrous metallic element of group 3 of the periodic table.<br/>Highly reactive but protected by a thin transparent layer of the oxide<br/>which quickly forms in air. There are many alloys of aluminum, as well as<br/>a good number of industrial uses. Makes up 8.1% of the Earth's crust, by<br/>weight. Isolated in 1825 by H.C. Oersted.<br/>
americium	americium<br/>Symbol: Am<br/>Atomic number: 95<br/>Atomic weight: (243)<br/>Radioactive metallic transuranic element, belongs to the actinoids. Ten<br/>known isotopes. Am-243 is the most stable isotope, with a half-life of<br/>7.95*10^3 years. Discovered by Glenn T. Seaborg and associates in 1945, it<br/>was obtained by bombarding {uranium}-238 with alpha particles.<br/>
antimony	antimony<br/>Symbol: Sb<br/>Atomic number: 51<br/>Atomic weight: 121.75<br/>Element of group 15. Multiple allotropic forms. The stable form of<br/>antimony is a blue-white metal. Yellow and black antimony are unstable<br/>non-metals. Used in flame-proofing, paints, ceramics, enamels, and rubber.<br/>Attacked by oxidizing acids and halogens. First reported by Tholden in<br/>1450.<br/>
argon	argon<br/>Symbol: Ar<br/>Atomic number: 18<br/>Atomic weight: 39.948<br/>Monatomic noble gas. Makes up 0.93% of the air. Colourless, odorless. Is<br/>inert and has no true compounds. Lord Rayleigh and Sir william Ramsey<br/>identified argon in 1894.<br/>
arsenic	arsenic<br/>Symbol: As<br/>Atomic number: 33<br/>Atomic weight: 74.922<br/>Metalloid element of group 15. There are three allotropes, yellow, black,<br/>and grey. Reacts with halogens, concentrated oxidizing acids and hot<br/>alkalis. Albertus Magnus is believed to have been the first to isolate the<br/>element in 1250.<br/>
astatine	astatine<br/>Symbol: At<br/>Atomic number: 85<br/>Atomic weight: (210)<br/>Radioactive halogen element. Occurs naturally from uranium and thorium<br/>decay. At least 20 known isotopes. At-210, the most stable, has a<br/>half-life of 8.3 hours. Synthesized by nuclear bombardment in 1940 by D.R.<br/>Corson, K.R. MacKenzie and E. Segre at the University of California.<br/>
barium	barium<br/>Symbol: Ba<br/>Atomic number: 56<br/>Atomic weight: 137.34<br/>Silvery-white reactive element, belonging to group 2 of the periodic<br/>table. Soluble barium compounds are extremely poisonous. Identified in<br/>1774 by Karl Scheele and extracted in 1808 by Humphry Davy.<br/>
berkelium	berkelium<br/>Symbol: Bk<br/>Atomic number: 97<br/>Atomic weight: (247)<br/>Radioactive metallic transuranic element. Belongs to actinoid series.<br/>Eight known isotopes, the most common Bk-247, has a half-life of<br/>1.4*10^3 years. First produced by Glenn T. Seaborg and associates in 1949<br/>by bombarding americium-241 with alpha particles.<br/>
beryllium	beryllium<br/>Symbol: Be<br/>Atomic number: 4<br/>Atomic weight: 9.0122<br/>Grey metallic element of group 2 of the periodic table. Is toxic and can<br/>cause severe lung diseases and dermatitis. Shows high covalent character.<br/>It was isolated independently by F. Wohler and A.A. Bussy in 1828.<br/>
bismuth	bismuth<br/>Symbol: Bi<br/>Atomic number: 83<br/>Atomic weight: 208.980<br/>White crystalline metal with a pink tinge, belongs to group 15. Most<br/>diamagnetic of all metals and has the lowest thermal conductivity of all<br/>the elements except mercury. Lead-free bismuth compounds are used in<br/>cosmetics and medical procedures. Burns in the air and produces a blue<br/>flame. In 1753, C.G. Junine first demonstrated that it was different from<br/>lead.<br/>
bohrium	bohrium<br/>Competing name for {unnilseptium}, the 107th element, proposed by the<br/>IUPAC in response to the discoverers of the element wanting to name it<br/>{nielsbohrium}.<br/>
boron	boron<br/>Symbol: B<br/>Atomic number: 5<br/>Atomic weight: 10.811<br/>An element of group 13 of the periodic table. There are two allotropes,<br/>amorphous boron is a brown power, but metallic boron is black. The<br/>metallic form is hard (9.3 on Mohs' scale) and a bad conductor in room<br/>temperatures. It is never found free in nature. Boron-10 is used in<br/>nuclear reactor control rods and shields. It was discovered in 1808 by Sir<br/>Humphry Davy and by J.L. Gay-Lussac and L.J. Thenard.<br/>
bromine	bromine<br/>Symbol: Br<br/>Atomic number: 35<br/>Atomic weight: 79.909<br/>Halogen element. Red volatile liquid at room temperature. Its reactivity<br/>is somewhere between chlorine and iodine. Harmful to human tissue in a<br/>liquid state, the vapour irritates eyes and throat. Discovered in 1826 by<br/>Antoine Balard.<br/>
cadmium	cadmium<br/>Symbol: Cd<br/>Atomic number: 48<br/>Atomic weight: 112.40<br/>Soft bluish metal belonging to group 12 of the periodic table. Extremely<br/>toxic even in low concentrations. Chemically similar to zinc, but lends<br/>itself to more complex compounds. Discovered in 1817 by F. Stromeyer.<br/>
caesium	caesium<br/>Symbol: Cs<br/>Atomic number: 55<br/>Atomic weight: 132.90545<br/>Soft silvery-white metallic element belonging to group 1 of the periodic<br/>table. One of the three metals which are liquid at room temperature. Cs-133<br/>is the natural, and only stable, isotope. Fifteen other radioisotopes exist.<br/>Caesium reacts explosively with cold water, and ice at temperatures above<br/>157K. Caesium hydroxide is the strongest base known. Caesium is the most<br/>electropositive, most alkaline and has the least ionization potential of<br/>all the elements. Known uses include the basis of atomic clocks, catalyst<br/>for the hydrogenation of some organic compounds, and in photoelectric cells.<br/>Caesium was discovered by Gustav Kirchoff and Robert Bunsen in Germany in<br/>1860 spectroscopically. Its identification was based upon the bright blue<br/>lines in its spectrum. The name comes from the latin word caesius, which<br/>means sky blue. Caesium should be considered highly toxic. Some of the<br/>radioisotopes are even more toxic.<br/>
calcium	calcium<br/>Symbol: Ca<br/>Atomic number: 20<br/>Atomic weight: 40.08<br/>Soft grey metallic element belonging to group 2 of the periodic table.<br/>Used a reducing agent in the extraction of thorium, zirconium and<br/>uranium. Essential element for living organisms.<br/>
californium	californium<br/>Symbol: Cf<br/>Atomic number: 98<br/>Atomic weight: (249)<br/>Radioactive metallic transuranic element. Belongs to actinoid series.<br/>Cf-251 has a half life of about 700 years. Nine isotopes are known.<br/>Cf-252 is an intense {neutron} source, which makes it an intense<br/>{neutron} source and gives it a use in {neutron} activation analysis<br/>and a possible use as a radiation source in medicine. First produced<br/>by Glenn T. Seaborg and associates in 1950.<br/>
carbon	carbon<br/>Symbol: C<br/>Atomic number: 6<br/>Atomic weight: 12.01115<br/>Carbon is a member of group 14 of the periodic table. It has three<br/>allotropic forms of it, diamonds, graphite and fullerite. Carbon-14<br/>is commonly used in radioactive dating. Carbon occurs in all organic life<br/>and is the basis of organic chemistry. Carbon has the interesting chemical<br/>property of being able to bond with itself, and a wide variety of other<br/>elements.<br/>
cerium	cerium<br/>Symbol: Ce<br/>Atomic number: 58<br/>Atomic weight: 140.12<br/>Silvery metallic element, belongs to the lanthanoids. Four natural<br/>isotopes exist, and fifteen radioactive isotopes have been identified.<br/>Used in some rare-earth alloys. The oxidized form is used in the glass<br/>industry. Discovered by Martin .H. Klaproth in 1803.<br/>
chlorine	chlorine<br/>Symbol: Cl<br/>Atomic number: 17<br/>Atomic weight: 35.453<br/>Halogen element. Poisonous greenish-yellow gas. Occurs widely in nature as<br/>sodium chloride in seawater. Reacts directly with many elements and<br/>compounds, strong oxidizing agent. Discovered by Karl Scheele in 1774.<br/>Humphrey David confirmed it as an element in 1810.<br/>
chromium	chromium<br/>Symbol: Cr<br/>Atomic number: 24<br/>Atomic weight: 51.996<br/>Hard silvery transition element. Used in decorative electroplating.<br/>Discovered in 1797 by Vauquelin.<br/>
cobalt	cobalt<br/>Symbol: Co<br/>Atomic number: 27<br/>Atomic weight: 58.993<br/>Light grey transition element. Some meteorites contain small amounts of<br/>metallic cobalt. Generally alloyed for use. Mammals require small amounts<br/>of cobalt salts. Cobalt-60, an artificially produced radioactive isotope<br/>of Cobalt is an important radioactive tracer and cancer-treatment agent.<br/>Discovered by G. Brandt in 1737.<br/>
columbium	columbium<br/>The original name for {niobium}.<br/>
copper	copper<br/>Symbol: Cu<br/>Atomic number: 29<br/>Atomic weight: 63.54<br/>Red-brown transition element. Known by the Romans as 'cuprum.' Extracted<br/>and used for thousands of years. Malleable, ductile and an excellent<br/>conductor of heat and electricity. When in moist conditions, a greenish<br/>layer forms on the outside.<br/>
cuprum	cuprum<br/>Roman name for {copper}.<br/>
curium	curium<br/>Symbol: Cm<br/>Atomic number: 96<br/>Atomic weight: (247)<br/>Radioactive metallic transuranic element. Belongs to actinoid series.<br/>Nine known isotopes, Cm-247 has a half-life of 1.64*10^7 years. First<br/>identified by Glenn T. Seaborg and associates in 1944, first produced by<br/>L.B. Werner and I. Perlman in 1947 by bombarding americium-241 with<br/>{neutron}s. Named for Marie Curie.<br/>
deuterium	deuterium<br/>Symbol: D<br/>Atomic Weight: 2<br/>A {hydrogen} atom which has but one proton and {neutron}. Deuterium makes up<br/>about 0.015% of all natural hydrogen. Chemical properties are like that of<br/>normal {hydrogen}, though somewhat slower.<br/>
dubnium	dubnium<br/>Symbol: Db<br/>Competing name for {unnilquadium}, the 104th element, proposed by the<br/>IUPAC.<br/>
dysprosium	dysprosium<br/>Symbol: Dy<br/>Atomic number: 66<br/>Atomic weight: 162.50<br/>Metallic with a bright silvery-white lustre. Dysprosium belongs to the<br/>lanthanoids. It is relatively stable in air at room temperatures, it will<br/>however dissolve in mineral acids, evolving hydrogen. It is found in<br/>from rare-earth minerals. There are seven natural isotopes of dysprosium,<br/>and eight radioisotopes, Dy-154 being the most stable with a half-life of<br/>3*10^6 years. Dysprosium is used as a neutron absorber in nuclear fission<br/>reactions, and in compact disks. It was discovered by Paul Emile Lecoq de<br/>Boisbaudran in 1886 in France. Its name comes from the Greek word<br/>dysprositos, which means hard to obtain.<br/>
einsteinium	einsteinium<br/>Symbol: Es<br/>Atomic number: 99<br/>Atomic weight: (254)<br/>Appearance is unknown, however it is most probably metallic and silver<br/>or gray in color. Radioactive metallic transuranic element belonging to the<br/>actinoids. Es-254 has the longest half-life of the eleven known isotopes at<br/>270 days. First identified by Albert Ghiorso and associates in the debris of<br/>the 1952 hydrogen bomb explosion. In 1961 the first microgram quantities of<br/>Es-232 were separated. While einsteinium never exists naturally, if a<br/>sufficient amount was assembled, it would pose a radiation hazard.<br/>
erbium	erbium<br/>Symbol: Er<br/>Atomic number: 68<br/>Atomic weight: 167.26<br/>Soft silvery metallic element which belongs to the lanthanoids. Six<br/>natural isotopes that are stable. Twelve artificial isotopes are known.<br/>Used in nuclear technology as a neutron absorber. It is being investigated<br/>for other possible uses. Discovered by Carl G. Mosander in 1843.<br/>
europium	europium<br/>Symbol: Eu<br/>Atomic number: 63<br/>Atomic weight: 151.25<br/>Soft silvery metallic element belonging to the lanthanoids. Eu-151 and<br/>Eu-153 are the only two stable isotopes, both of which are {neutron}<br/>absorbers. Discovered in 1889 by Sir William Crookes.<br/>
fermium	fermium<br/>Symbol: Fm<br/>Atomic number: 100<br/>Atomic weight: (253)<br/>Radioactive metallic transuranic element, belongs to the actinoids. Ten<br/>known isotopes, most stable is Fm-257 with a half-life of 10 days. First<br/>identified by Albert Ghiorso and associates in the debris of the first<br/>hydrogen-bomb explosion in 1952.<br/>
fluorine	fluorine<br/>Symbol: F<br/>Atomic number: 9<br/>Atomic weight: 18.9984<br/>A poisonous pale yellow gaseous element belonging to group 17 of the<br/>periodic table (The halogens). It is the most chemically reactive and<br/>electronegative element. It is highly dangerous, causing severe chemical<br/>burns on contact with flesh. Fluorine was identified by Scheele in 1771<br/>and first isolated by Moissan in 1886.<br/>
francium	francium<br/>Symbol: Fr<br/>Atomic number: 87<br/>Atomic weight: (223)<br/>Radioactive element, belongs to group 1 of the periodic table. Found in<br/>uranium and thorium ores. The 22 known isotopes are all radioactive, with<br/>the most stable being Fr-223. Its existence was confirmed in 1939 by<br/>Marguerite Perey.<br/>
gadolinium	gadolinium<br/>Symbol: Gd<br/>Atomic number: 64<br/>Atomic weight: 157.25<br/>Soft silvery metallic element belonging to the lanthanoids. Seven natural,<br/>stable isotopes are known in addition to eleven artificial isotopes.<br/>Gd-155 and Gd-157 and the best neutron absorbers of all elements.<br/>Gadolinium compounds are used in electronics. Discovered by J.C.G Marignac<br/>in 1880.<br/>
gallium	gallium<br/>Symbol: Ga<br/>Atomic number: 31<br/>Atomic weight: 69.72<br/>Soft silvery metallic element, belongs to group 13 of the periodic table.<br/>The two stable isotopes are Ga-69 and Ga-71. Eight radioactive isotopes<br/>are known, all having short half-lives. Gallium Arsenide is used as a<br/>semiconductor. Corrodes most other metals by diffusing into their lattice.<br/>First identified by Francois Lecoq de Boisbaudran in 1875.<br/>
germanium	germanium<br/>Symbol: Ge<br/>Atomic number: 32<br/>Atomic weight: 72.59<br/>Lustrous hard metalloid element, belongs to group 14 of the periodic<br/>table. Forms a large number of organometallic compounds. Predicted by<br/>Mendeleev in 1871, it was actually found in 1886 by Winkler.<br/>
gold	gold<br/>Symbol: Au<br/>Atomic number: 79<br/>Atomic weight: 196.96655<br/>Gold is gold colored. It is the most malleable and ductile metal known.<br/>There is only one stable isotope of gold, and five radioisotopes of gold,<br/>Au-195 being the most stable with a half-life of 186 days. Gold is used<br/>as a monetary standard, in jewelry, dentistry, electronics. Au-198 is used<br/>in treating cancer and some other medical conditions. Gold has been known<br/>to exist as far back as 2600 BC. Gold comes from the Anglo-Saxon word gold.<br/>Its symbol, Au, comes from the Latin word aurum, which means gold. Gold is<br/>not particularly toxic, however it is known to cause damage to the liver<br/>and kidneys in some.<br/>
hafnium	hafnium<br/>Symbol: Hf<br/>Atomic number: 72<br/>Atomic weight: 178.49<br/>Silvery lustrous metallic transition element. Used in tungsten alloys in<br/>filaments and electrodes, also acts as a neutron absorber. First reported<br/>by Urbain in 1911, existence was finally established in 1923 by D. Coster,<br/>G.C. de Hevesy in 1923.<br/>
hahnium	hahnium<br/>Symbol: Ha<br/>Competing name for {unnilpentium}, the 105th element, proposed by the<br/>American Chemical Society. Also a competing name for {unniloctium}, the<br/>108th element, proposed by the IUPAC. Both were chosen in honor of German<br/>researcher, Otto Hahn.<br/>
hassium	hassium<br/>Competing name for {unniloctium}, the 108th element, proposed by its<br/>German discoverers and supported by the American Chemical Society.<br/>
helium	helium<br/>Symbol: He<br/>Atomic number: 2<br/>Atomic weight: 4.0026<br/>Colourless, odourless gaseous nonmetallic element. Belongs to group 18 of<br/>the periodic table. Lowest boiling point of all elements and can only be<br/>solidified under pressure. Chemically inert, no known compounds.<br/>Discovered in the solar spectrum in 1868 by Lockyer.<br/>
holmium	holmium<br/>Symbol: Ho<br/>Atomic number: 67<br/>Atomic weight: 167.26<br/>Relatively soft and malleable silvery-white metallic element, which is stable<br/>in dry air at room temperature. It oxidizes in moist air and at high<br/>temperatures. It belongs to the lanthanoids. A rare-earth metal, it is found<br/>in the minerals monazite and gadolinite. It possesses unusual magnetic<br/>properties. One natural isotope, Ho-165 exists, six radioisotopes exist, the<br/>most stable being Ho-163 with a half-life of 4570 years. Holmium is used in<br/>some metal alloys, it is also said to stimulate the metabolism. Discovered by<br/>Per Theodor Cleve and J.L. Soret in Switzerland in 1879. The name homium comes<br/>from the Greek word Holmia which means Sweden. While all holmium compounds<br/>should be considered highly toxic, initial evidence seems to indicate that<br/>they do not pose much danger. The metal's dust however, is a fire hazard.<br/>
hydrogen	hydrogen<br/>Symbol: H<br/>Atomic number: 1<br/>Atomic weight: 1.0079<br/>Colourless, odourless gaseous chemical element. Lightest and most<br/>abundant element in the universe. Present in water and in all organic<br/>compounds. Chemically reacts with most elements. Discovered by Henry<br/>Cavendish in 1776.<br/>
indium	indium<br/>Symbol: In<br/>Atomic number: 49<br/>Atomic weight: 114.82<br/>Soft silvery element belonging to group 13 of the periodic table. The most<br/>common natural isotope is In-115, which has a half-life of 6*10^4 years.<br/>Five other radioisotopes exist. Discovered in 1863 by Reich and Richter.<br/>
iodine	iodine<br/>Symbol: I<br/>Atomic number: 53<br/>Atomic weight: 126.904<br/>Dark violet nonmetallic element, belongs to group 17 of the periodic<br/>table. Insoluble in water. Required as a trace element for living<br/>organisms. One stable isotope, I-127 exists, in addition to fourteen<br/>radioactive isotopes. Chemically the least reactive of the halogens, and<br/>the most electropositive metallic halogen. Discovered in 1812 by Courtois.<br/>
iridium	iridium<br/>Symbol: Ir<br/>Atomic number: 77<br/>Atomic weight: 192.217<br/>Very hard and brittle, silvery metallic transition element. It has a<br/>yellowish cast to it. Salts of iridium are highly colored. It is the<br/>most corrosion resistant metal known, not attacked by any acid, but is<br/>attacked by molten salts. There are two natural isotopes of iridium, and<br/>4 radioisotopes, the most stable being Ir-192 with a half-life of 73.83<br/>days. Ir-192 decays into {platinum}, while the other radioisotopes decay<br/>into {osmium}. Iridium is used in high temperature apparatus, electrical<br/>contacts, and as a hardening agent for platinum. Discovered in 1803 by<br/>Smithson Tennant in England. The name comes from the Greek word iris, which<br/>means rainbow. Iridium metal is generally non-toxic due to its relative<br/>unreactivity, but iridium compounds should be considered highly toxic.<br/>
iron	iron<br/>Symbol: Fe<br/>Atomic number: 26<br/>Atomic weight: 55.847<br/>Silvery malleable and ductile metallic transition element. Has nine<br/>isotopes and is the fourth most abundant element in the earth's crust.<br/>Required by living organisms as a trace element (used in hemoglobin in<br/>humans.) Quite reactive, oxidizes in moist air, displaces hydrogen from<br/>dilute acids and combines with nonmetallic elements.<br/>
IUPAC	IUPAC<br/>The International Union of Pure and Applied Chemistry.<br/>
joliotium	joliotium<br/>Symbol: Jl<br/>Competing name for {unnilpentium}, the 105th element, proposed by the<br/>IUPAC.<br/>
krypton	krypton<br/>Symbol: Kr<br/>Atomic number: 36<br/>Atomic weight: 83.80<br/>Colorless gaseous element, belongs to the noble gases. Occurs in the air,<br/>0.0001% by volume. It can be extracted from liquid air by fractional<br/>distillation. Generally not isolated, but used with other inert gases in<br/>fluorescent lamps. Five natural isotopes, and five radioactive isotopes.<br/>Kr-85, the most stable radioactive isotope, has a half-life of 10.76<br/>years and is produced in fission reactors. Practically inert, though known<br/>to form compounds with {fluorine}.<br/>
kurchatovium	kurchatovium<br/>Symbol: Ku<br/>Competing name for {unnilquadium}, the 104th element, proposed by Russian<br/>scientists.<br/>
lanthanum	lanthanum<br/>Symbol: La<br/>Atomic number: 57<br/>Atomic weight: 138.9055<br/>(From the Greek word lanthanein, to line hidden) Silvery metallic element<br/>belonging to group 3 of the periodic table and oft considered to be one of<br/>the lanthanoids. Found in some rare-earth minerals. Twenty-five natural<br/>isotopes exist. La-139 which is stable, and La-138 which has a half-life<br/>of 10^10 to 10^15 years. The other twenty-three isotopes are radioactive.<br/>It resembles the lanthanoids chemically. Lanthanum has a low to moderate<br/>level of toxicity, and should be handled with care. Discovered in 1839 by<br/>C.G. Mosander.<br/>
lawrencium	lawrencium<br/>Symbol: Lr<br/>Atomic number: 103<br/>Atomic weight: (262)<br/>Appearance unknown, however it is most likely silvery-white or grey<br/>and metallic. Lawrencium is a synthetic rare-earth metal. There are<br/>eight known radioisotopes, the most stable being Lr-262 with a half-life<br/>of 3.6 hours. Due to the short half-life of lawrencium, and its<br/>radioactivity, there are no known uses for it. Identified by Albert Ghiorso<br/>in 1961 at Berkeley. It was produced by bombarding californium with boron<br/>ions. The name is temporary {IUPAC} nomenclature, the origin of the name<br/>comes from Ernest O. Lawrence, the inventor of the cyclotron. If sufficient<br/>amounts of lawrencium were produced, it would pose a radiation hazard.<br/>
lead	lead<br/>Symbol: Pb<br/>Atomic number: 82<br/>Atomic weight: 207.19<br/>Heavy dull grey ductile metallic element, belongs to group 14. Used in<br/>building construction, lead-place accumulators, bullets and shot, and is<br/>part of solder, pewter, bearing metals, type metals and fusible alloys.<br/>
lithium	lithium<br/>Symbol: Li<br/>Atomic number: 3<br/>Atomic weight: 6.939<br/>Socket silvery metal. First member of group 1 of the periodic table.<br/>Lithium salts are used in psychomedicine.<br/>
lutetium	lutetium<br/>Symbol: Lu<br/>Atomic number: 71<br/>Atomic weight: 194.967<br/>Silvery-white rare-earth metal which is relatively stable in air. It<br/>happens to be the most expensive rare-earth metal. Its found with almost<br/>all rare-earth metals, but is very difficult to separate from other<br/>elements. Least abundant of all natural elements. Used in metal alloys,<br/>and as a catalyst in various processes. There are two natural, stable<br/>isotopes, and seven radioisotopes, the most stable being Lu-174 with a<br/>half-life of 3.3 years. The separation of lutetium from {ytterbium} was<br/>described by Georges Urbain in 1907. It was discovered at approximately<br/>the same time by Carl Auer von Welsbach. The name comes from the Greek<br/>word lutetia which means Paris.<br/>
magnesium	magnesium<br/>Symbol: Mg<br/>Atomic number: 12<br/>Atomic weight: 24.312<br/>Silvery metallic element belonging to group 2 of the periodic table<br/>(alkaline-earth metals). It is essential for living organisms, and is used<br/>in a number of light alloys. Chemically very reactive, it forms a<br/>protective oxide coating when exposed to air and burns with an intense<br/>white flame. It also reacts with sulphur, nitrogen and the halogens. First<br/>isolated by Bussy in 1828.<br/>
manganese	manganese<br/>Symbol: Mn<br/>Atomic number: 25<br/>Atomic weight: 54.938<br/>Grey brittle metallic transition element. Rather electropositive, combines<br/>with some non-metals when heated. Discovered in 1774 by Scheele.<br/>
meitnerium	meitnerium<br/>Symbol: Mt<br/>Atomic number: 109<br/>Atomic weight: (266)<br/>Half-life of approximately 5ms. The creation of this element demonstrated<br/>that fusion techniques could indeed be used to make new, heavy nuclei.<br/>Made and identified by physicists of the Heavy Ion Research Laboratory,<br/>Darmstadt, West Germany in 1982. Named in honor of Lise Meitner the<br/>Austrian physicist.<br/>
mendelevium	mendelevium<br/>Symbol: Md<br/>Atomic number: 101<br/>Atomic weight: (256)<br/>Radioactive metallic transuranic element. Belongs to the actinoid series.<br/>Only known isotope, Md-256 has a half-life of 1.3 hours. First identified<br/>by Glenn T. Seaborg, Albert Ghiorso and associates in 1955. Alternative<br/>name {unnilunium} has been proposed. Named after the 'inventor' of the<br/>periodic table, Dmitri Mendeleev.<br/>
mercury	mercury<br/>Symbol: Hg<br/>Atomic number: 80<br/>Atomic weight: 200.59<br/>Heavy silvery liquid metallic element, belongs to the zinc group. Used in<br/>thermometers, barometers and other scientific apparatus. Less reactive<br/>than zinc and cadmium, does not displace hydrogen from acids. Forms a<br/>number of complexes and organomercury compounds.<br/>
molybdenum	molybdenum<br/>Symbol: Mo<br/>Atomic number: 42<br/>Atomic weight: 95.94<br/>Silvery-white, hard metallic transition element. It is chemically<br/>unreactive and is not affected by most acids. It oxidizes at high<br/>temperatures. There are seven natural isotopes, and four radioisotopes,<br/>Mo-93 being the most stable with a half-life of 3500 years. Molybdenum<br/>is used in almost all high-strength steels, it has nuclear applications,<br/>and is a catalyst in petroleum refining. Discovered in 1778 by Carl<br/>Welhelm Scheele of Sweden. Impure metal was prepared in 1782 by Peter<br/>Jacob Hjelm. The name comes from the Greek word molybdos which means lead.<br/>Trace amounts of molybdenum are required for all known forms of life.<br/>All molybdenum compounds should be considered highly toxic, and will<br/>also cause severe birth defects.<br/>
neodymium	neodymium<br/>Symbol: Nd<br/>Atomic number: 60<br/>Atomic weight: 144.24<br/>Soft bright silvery metallic element, belongs to the lanthanoids. Seven natural<br/>isotopes, Nd-144 being the only radioactive one with a half-life of 10^10<br/>to 10^15 years. Six artificial radioisotopes have been produced. The<br/>metal is used in glass works to color class a shade of violet-purple and<br/>make it dichroic. One of the more reactive rare-earth metals, quickly reacts<br/>with air. Used in some rare-earth alloys. Neodymium is used to color<br/>the glass used in welder's glasses. Neodymium is also used in very<br/>powerful, permanent magnets (Nd2Fe14B). Discovered by Carl F. Auer von<br/>Welsbach in Austria in 1885 by separating didymium into its elemental<br/>components {praseodymium} and neodymium. The name comes from the Greek words<br/>"neos didymos" which means "new twin". Neodymium should be considered<br/>highly toxic, however evidence would seem to show that it acts as little<br/>more than a skin and eye irritant. The dust however, presents a fire and<br/>explosion hazard.<br/>
neon	neon<br/>Symbol: Ne<br/>Atomic number: 10<br/>Atomic weight: 20.183<br/>Colourless gaseous element of group 18 on the periodic table (noble<br/>gases). Neon occurs in the atmosphere, and comprises 0.0018% of the volume<br/>of the atmosphere. It has a distinct reddish glow when used in discharge<br/>tubes and neon based lamps. It forms almost no chemical compounds. Neon<br/>was discovered in 1898 by Sir William Ramsey and M.W. Travers.<br/>
neptunium	neptunium<br/>Symbol: Np<br/>Atomic number: 93<br/>Atomic weight: (237)<br/>Radioactive metallic transuranic element, belongs to the actinoids.<br/>Np-237, the most stable isotope, has a half-life of 2.2*10^6 years and is<br/>a by product of nuclear reactors. The other known isotopes have mass<br/>numbers 229 through 236, and 238 through 241. Np-236 has a half-life of<br/>5*10^3 years. First produced by Edwin M. McMillan and P.H. Abelson in<br/>1940.<br/>
neutron	neutron<br/>Weight: 1.6749286*10^-27kg<br/>A neutral hadron that is stable in the atomic nucleus but decays into a<br/>protron, an electron and an antineutrino with a mean life of 12 minutes<br/>outside the nucleus. Neutrons exist in all atomic nuclei except normal<br/>hydrogen. Reported in 1932 by James Chadwick.<br/>
nickel	nickel<br/>Symbol: Ni<br/>Atomic number: 28<br/>Atomic weight: 58.71<br/>Malleable ductile silvery metallic transition element. Discovered by A.F.<br/>Cronstedt in 1751.<br/>
nielsbohrium	nielsbohrium<br/>Competing name for {unnilseptium}, the 107th element, proposed by its West<br/>German discoverers and supported by the American Chemical Society. The<br/>name was chosen in honor of physicist, Niels Bohr.<br/>
niobium	niobium<br/>Symbol: Nb<br/>Atomic number: 41<br/>Atomic weight: 92.906<br/>Soft, ductile grey-blue metallic transition element. Used in special<br/>steels and in welded joints to increase strength. Combines with halogens<br/>and oxidizes in air at 200 degrees celsius. Discovered by Charles Hatchett<br/>in 1801 and isolated by Blomstrand in 1864. Called {columbium} originally.<br/>
nitrogen	nitrogen<br/>Symbol: N<br/>Atomic number: 7<br/>Atomic weight: 14.0067<br/>Colourless, gaseous element which belongs to group 15 of the periodic<br/>table. Constitutes ~78% of the atmosphere and is an essential part of the<br/>ecosystem. Nitrogen for industrial purposes is acquired by the fractional<br/>distillation of liquid air. Chemically inactive, reactive generally only<br/>at high temperatures or in electrical discharges. It was discovered in<br/>1772 by D. Rutherford.<br/>
nobelium	nobelium<br/>Symbol: No<br/>Atomic number: 102<br/>Atomic weight: (254)<br/>Radioactive metallic transuranic element, belongs to the actinoids. Seven<br/>known isotopes exist, the most stable being No-254 with a half-life of 255<br/>seconds. First identified with certainty by Albert Ghiorso and Glenn T.<br/>Seaborg in 1966. {Unnilbium} has been proposed as an alternative name.<br/>
osmium	osmium<br/>Symbol: Os<br/>Atomic number: 76<br/>Atomic weight: 190.2<br/>Hard blue-white metallic transition element. Found with platinum and used<br/>in some alloys with platinum and iridium.<br/>
oxygen	oxygen<br/>Symbol: O<br/>Atomic number: 8<br/>Atomic weight: 15.9994<br/>A colourless, odourless gaseous element belonging to group 16 of the<br/>periodic table. It is the most abundant element present in the earth's<br/>crust. It also makes up 20.8% of the Earth's atmosphere. For industrial<br/>purposes, it is separated from liquid air by fractional distillation. It<br/>is used in high temperature welding, and in breathing. It commonly comes<br/>in the form of Oxygen, but is found as Ozone in the upper atmosphere. It<br/>was discovered by Priestley in 1774.<br/>
palladium	palladium<br/>Symbol: Pd<br/>Atomic number: 46<br/>Atomic weight: 106.4<br/>Soft white ductile transition element. Found with some copper and nickel<br/>ores. Does not react with oxygen at normal temperatures. Dissolves slowly<br/>in hydrochloric acid. Discovered in 1803 by W.H. Wollaston.<br/>
phosphorus	phosphorus<br/>Symbol: P<br/>Atomic number: 15<br/>Atomic weight: 30.9738<br/>Non-metallic element belonging to group 15 of the periodic table. Has a<br/>multiple allotropic forms. Essential element for living organisms. It was<br/>discovered by Brandt in 1669.<br/>
platinum	platinum<br/>Symbol: Pt<br/>Atomic number: 78<br/>Atomic weight: 195.078<br/>Attractive greyish-white metal. When pure, it is malleable and ductile.<br/>Does not oxidize in air, insoluble in hydrochloric and nitric acid.<br/>Corroded by halogens, cyandies, sulphur and alkalis. {Hydrogen} and<br/>{oxygen} react explosively in the presence of platinum. There are six<br/>stable isotopes and three radioisotopes, the most stable being Pt-193<br/>with a half-life of 60 years. Platinum is used in jewelry, laboratory<br/>equipment, electrical contacts, dentistry, and anti-pollution devices in<br/>cars. PtCl2(NH3)2 is used to treat some forms of cancer. Platinum-{cobalt}<br/>alloys have magnetic properties. It is also used in the definition of<br/>the Standard Hydrogen Electrode. Discovered by Antonio de Ulloa in South<br/>America in 1735. The name comes from the Spanish word platina which means<br/>silver. Platinum metal is generally not a health concern due to its<br/>unreactivity, however platinum compounds should be considered highly<br/>toxic.<br/>
plutonium	plutonium<br/>Symbol: Pu<br/>Atomic number: 94<br/>Atomic weight: (242)<br/>Dense silvery radioactive metallic transuranic element, belongs to the<br/>actinoids. Pu-244 is the most stable isotope with a half-life of 7.6*10^7<br/>years. Thirteen isotopes are known. Pu-239 is the most important, it<br/>undergoes nuclear fission with slow neutrons and is hence important to<br/>nuclear weapons and reactors. Plutonium production is monitored down to<br/>the gram to prevent military misuse. First produced by Gleen T. Seaborg,<br/>Edwin M. McMillan, J.W. Kennedy and A.C. Wahl in 1940.<br/>
polonium	polonium<br/>Symbol: Po<br/>Atomic number: 84<br/>Atomic weight: (210)<br/>Rare radioactive metallic element, belongs to group 16 of the periodic<br/>table. Over 30 known isotopes exist, the most of all elements. Po-209 has<br/>a half-life of 103 years. Possible uses in heating spacecraft. Discovered<br/>by Marie Curie in 1898 in a sample of pitchblende.<br/>
potassium	potassium<br/>Symbol: K<br/>Atomic number: 19<br/>Atomic weight: 39.0983<br/>Soft silvery metallic element belonging to group 1 of the periodic table<br/>(alkali metals). Occurs naturally in seawater and a many minerals. Highly<br/>reactive, chemically, it resembles sodium in its behavior and compounds.<br/>Discovered by Sir Humphry Davy in 1807.<br/>
praseodymium	praseodymium<br/>Symbol: Pr<br/>Atomic number: 59<br/>Atomic weight: 140.907<br/>Soft silvery metallic element, belongs to the lanthanoids. Only natural<br/>isotope is Pr-141 which is not radioactive.  Fourteen radioactive isotopes<br/>have been artificially produced. Used in rare-earth alloys. Discovered in<br/>1885 by C.A. von Welsbach.<br/>
promethium	promethium<br/>Symbol: Pm<br/>Atomic number: 61<br/>Atomic weight: (147)<br/>Soft silvery metallic element, belongs to the lanthanoids. Pm-147, the<br/>only natural isotope, is radioactive and has a half-life of 252 years.<br/>Eighteen radioisotopes have been produced, but all have very short<br/>half-lives. Found only in nuclear decay waste. Pm-147 is of interest as a<br/>beta-decay source, however Pm-146 and Pm-148 have to be removed from it<br/>first, as they generate gamma radiation. Discovered by J.A. Marinsky,<br/>L.E. Glendenin and C.D. Coryell in 1947.<br/>
protactinium	protactinium<br/>Symbol: Pa<br/>Atomic number: 91<br/>Atomic weight: (231)<br/>Radioactive metallic element, belongs to the actinoids. The most stable<br/>isotope, Pa-231 has a half-life of 2.43*10^4 years. At least 10 other<br/>radioactive isotopes are known. No practical applications are known.<br/>Discovered in 1917 by Lise Meitner and Otto Hahn.<br/>
radium	radium<br/>Symbol: Ra<br/>Atomic number: 88<br/>Atomic weight: (226)<br/>Radioactive metallic transuranic element, belongs to group 2 of the<br/>periodic table. Most stable isotope, Ra-226 has a half-life of 1602 years,<br/>which decays into radon. Isolated from pitchblende in 1898 Marie and<br/>Pierre Curie.<br/>
radon	radon<br/>Symbol: Rn<br/>Atomic number: 86<br/>Atomic weight: (222)<br/>Colorless radioactive gaseous element, belongs to the noble gases. Of the<br/>twenty known isotopes, the most stable is Rn-222 with a half-life of 3.8 days.<br/>Formed by the radioactive decay of {Radium}-226. Radon itself decays into<br/>{polonium}. Used in radiotherapy. As a noble gas, it is effectively inert,<br/>though radon fluoride has been synthesized. First isolated in 1908 by Ramsey<br/>and Gray.<br/>
rhenium	rhenium<br/>Symbol: Re<br/>Atomic number: 75<br/>Atomic weight: 186.2<br/>Silvery-white metallic transition element. Obtained as a by-product of<br/>molybdenum refinement. Rhenium-molybdenum alloys are superconducting.<br/>
rhodium	rhodium<br/>Symbol: Rh<br/>Atomic number: 45<br/>Atomic weight: 102.905<br/>Silvery white metallic transition element. Found with platinum and used in<br/>some platinum alloys. Not attacked by acids, dissolves only in aqua regia.<br/>Discovered in 1803 by W.H. Wollaston.<br/>
rubidium	rubidium<br/>Symbol: Rb<br/>Atomic number: 37<br/>Atomic weight: 85.47<br/>Soft silvery metallic element, belongs to group 1 of the periodic table.<br/>Rb-97, the naturally occurring isotope, is radioactive. It is highly<br/>reactive, with properties similar to other elements in group 1, like<br/>igniting spontaneously in air. Discovered spectroscopically in 1861 by W.<br/>Bunsen and G.R. Kirchoff.<br/>
ruthenium	ruthenium<br/>Symbol: Ru<br/>Atomic number: 44<br/>Atomic weight: 101.07<br/>Hard white metallic transition element. Found with platinum, used as a<br/>catalyst in some platinum alloys. Dissolves in fused alkalis, and is not<br/>attacked by acids. Reacts with halogens and oxygen at high temperatures.<br/>Isolated in 1844 by K.K. Klaus.<br/>
rutherfordium	rutherfordium<br/>Symbol: Rf<br/>Competing name for {unnilquadium}, the 104th element, proposed by the<br/>American Chemical Society.<br/>
samarium	samarium<br/>Symbol: Sm<br/>Atomic number: 62<br/>Atomic weight: 150.35<br/>Soft silvery metallic element, belongs to the lanthanoids. Seven natural<br/>isotopes, Sm-147 is the only radioisotope, and has a half-life of<br/>2.5*10^11 years. Used for making special alloys needed in the production<br/>of nuclear reactors. Also used as a neutron absorber. Small quantities of<br/>samarium oxide is used in special optical glasses. The largest use of the<br/>element is its ferromagnetic alloy which produces permanent magnets that<br/>are five times stronger than magnets produced by any other material.<br/>Discovered by Francois Lecoq de Boisbaudran in 1879.<br/>
scandium	scandium<br/>Symbol: Sc<br/>Atomic number: 21<br/>Atomic weight: 44.956<br/>Rare soft silvery metallic element belonging to group 3 of the periodic<br/>table. There are ten isotopes, nine of which are radioactive and have<br/>short half-lives. Predicted in 1869 by Mendeleev, isolated by Nilson in<br/>1879.<br/>
seaborgium	seaborgium<br/>Name proposed for the 106th element ({unnilhexium}) by the American<br/>Chemical Society in honor of Gleen T. Seaborg, an American nuclear<br/>physicist and Nobel prize winner.<br/>
selenium	selenium<br/>Symbol: Se<br/>Atomic number: 34<br/>Atomic weight: 78.96<br/>Metalloid element, belongs to group 16 of the periodic table. Multiple<br/>allotropic forms exist. Chemically resembles sulphur. Discovered in 1817<br/>by Jons J. Berzelius.<br/>
silicon	silicon<br/>Symbol: Si<br/>Atomic number: 14<br/>Atomic weight: 28.086<br/>Metalloid element belonging to group 14 of the periodic table. It is the<br/>second most abundant element in the Earth's crust, making up 25.7% of it<br/>by weight. Chemically less reactive than carbon. First identified by<br/>Lavoisier in 1787 and first isolated in 1823 by Berzelius.<br/>
silver	silver<br/>Symbol: Ag<br/>Atomic number: 47<br/>Atomic weight: 107.870<br/>White lustrous soft metallic transition element. Found in both its<br/>elemental form and in minerals. Used in jewellery, tableware and so on.<br/>Less reactive than silver, chemically.<br/>
sodium	sodium<br/>Symbol: Na<br/>Atomic number: 11<br/>Atomic weight: 22.9898<br/>Soft silvery reactive element belonging to group 1 of the periodic table<br/>(alkali metals). It is highly reactive, oxidizing in air and reacting<br/>violently with water, forcing it to be kept under oil. It was first<br/>isolated by Humphrey Davy in 1807.<br/>
strontium	strontium<br/>Symbol: Sr<br/>Atomic number: 38<br/>Atomic weight: 87.62<br/>Soft yellowish metallic element, belongs to group 2 of the periodic<br/>table. Highly reactive chemically. Sr-90 is present in radioactive fallout<br/>and has a half-life of 28 years. Discovered in 1798 by Klaproth and Hope,<br/>isolated in 1808 by Humphry Davy.<br/>
sulphur	sulphur<br/>Symbol: S<br/>Atomic number: 16<br/>Atomic weight: 32.064<br/>Yellow, nonmetallic element belonging to group 16 of the periodic table.<br/>It is an essential element in living organisms, needed in the amino acids<br/>cysteine and methionine, and hence in many proteins. Absorbed by plants<br/>from the soil as sulphate ion.<br/>
tantalum	tantalum<br/>Symbol: Ta<br/>Atomic number: 73<br/>Atomic weight: 180.948<br/>Heavy blue-grey metallic transition element. Ta-181 is a stable isotope,<br/>and Ta-180 is a radioactive isotope, with a half-life in excess of 10^7<br/>years. Used in surgery as it is unreactive. Forms a passive oxide layer in<br/>air. Identified in 1802 by Ekeberg and isolated in 1820 by Jons J.<br/>Berzelius.<br/>
technetium	technetium<br/>Symbol: Tc<br/>Atomic number: 43<br/>Atomic weight: (98)<br/>Radioactive metallic transition element. Can be detected in some stars and<br/>the fission products of uranium. First made by Perrier and Segre by<br/>bombarding molybdenum with deutrons, giving them Tc-97. Tc-99 is the most<br/>stable isotope with a half-life of 2.6*10^6 years. Sixteen isotopes are<br/>known. Organic technetium compounds are used in bone imaging. Chemical<br/>properties are intermediate between rhenium and manganese.<br/>
tellurium	tellurium<br/>Symbol: Te<br/>Atomic number: 52<br/>Atomic weight: 127.60<br/>Silvery metalloid element of group 16. Eight natural isotopes, nine<br/>radioactive isotopes. Used in semiconductors and to a degree in some<br/>steels. Chemistry is similar to {sulphur}. Discovered in 1782 by Franz<br/>Miller.<br/>
terbium	terbium<br/>Symbol: Tb<br/>Atomic number: 65<br/>Atomic weight: 158.924<br/>Silvery metallic element belonging to the lanthanoids. Tb-159 is the only<br/>stable isotope, there are seventeen artificial isotopes. Discovered by<br/>G.G. Mosander in 1843.<br/>
thallium	thallium<br/>Symbol: Tl<br/>Atomic number: 81<br/>Atomic weight: 204.3833<br/>Pure, unreacted thallium appears silvery-white and exhibits a metallic<br/>lustre. Upon reacting with air, it begins to turn bluish-grey and looks<br/>like lead. It is very malleable, and can be cut with a knife. There are<br/>two stable isotopes, and four radioisotopes, Tl-204 being the most stable<br/>with a half-life of 3.78 years. Thallium sulphate was used as a rodenticide.<br/>Thallium sulphine's conductivity changes with exposure to infrared light,<br/>this gives it a use in infrared detectors. Discovered by Sir William Crookes<br/>via spectroscopy. Its name comes from the Greek word thallos, which means<br/>green twig. Thallium and its compounds are toxic and can cause cancer.<br/>
thorium	thorium<br/>Symbol: Th<br/>Atomic number: 90<br/>Atomic weight: 232.038<br/>Grey radioactive metallic element. Belongs to actinoids. Found in monazite sand<br/>in Brazil, India and the US.  Thorium-232 has a half-life of 1.39x10^10 years.<br/>Can be used as a nuclear fuel for breeder reactors. Thorium-232 captures slow<br/>{neutron}s and breeds uranium-233. Discovered by Jons J. Berzelius in<br/>1829.<br/>
thulium	thulium<br/>Symbol: Tm<br/>Atomic number: 69<br/>Atomic weight: 168.934<br/>Soft grey metallic element that belongs to the lanthanoids. One natural<br/>isotope exists, Tm-169, and seventeen artificial isotopes have been<br/>produced. No known uses for the element. Discovered in 1879 by Per Theodor<br/>Cleve.<br/>
tin	tin<br/>Symbol: Sn<br/>Atomic number: 50<br/>Atomic weight: 118.69<br/>Silvery malleable metallic element belonging to group 14 of the periodic<br/>table. Twenty-six isotopes are known, five of which are radioactive.<br/>Chemically reactive. Combines directly with chlorine and oxygen and<br/>displaces hydrogen from dilute acids.<br/>
titanium	titanium<br/>Symbol: Ti<br/>Atomic number: 22<br/>Atomic weight: 47.90<br/>White metallic transition element. Occurs in numerous minerals. Used in<br/>strong, light corrosion-resistant alloys. Forms a passive oxide coating<br/>when exposed to air. First discovered by Gregor in 1789.<br/>
tungsten	tungsten<br/>Symbol: W<br/>Atomic number: 74<br/>Atomic weight: 183.85<br/>White or grey metallic transition element, formerly called {wolfram}.<br/>Forms a protective oxide in air and can be oxidized at high temperature.<br/>First isolated by Jose and Fausto de Elhuyer in 1783.<br/>
unnilbium	unnilbium<br/>Symbol: Unb<br/>Name proposed by the {IUPAC} to settle the dispute over naming the 102nd<br/>element {nobelium}.<br/>
unnildecium	unnildecium<br/>Symbol: Unn<br/>Atomic number: 110<br/>Atomic weight: (272)?<br/>Half-life of approximately 10ms. Reported in 1994 by German researchers at<br/>Darmstadt, Germany.<br/>
unnilhexium	unnilhexium<br/>Symbol:<br/>Atomic number: 106<br/>Atomic weight: (263)<br/>Half-life of 0.9 +/- 0.2 s. Discovered by the Joint Institute for Nuclear<br/>Research at Dubna (U.S.S.R.) in June of 1974. Its existence was confirmed<br/>by the Lawrence Berkeley Laboratory and Livermore National Laboratory in<br/>September of 1974.<br/>
unniloctium	unniloctium<br/>Symbol: Uno<br/>Atomic number: 108<br/>Atomic weight: (265)<br/>Radioactive transition metal.<br/>
unnilpentium	unnilpentium<br/>Symbol: Unp<br/>Atomic number: 105<br/>Atomic weight: (262)<br/>Radioactive transactinide element. Half-life of 1.6s. Discovered in 1970<br/>by Berkeley researchers. So far, seven isotopes have been discovered.<br/>
unnilquadium	unnilquadium<br/>Symbol: Unq<br/>Atomic number: 104<br/>Atomic weight: (261)<br/>Radioactive transactinide element. Expected to have similar chemical<br/>properties to those displayed by hafnium. Rf-260 was discovered by the<br/>Joint Nuclear Research Institute at Dubna (U.S.S.R.) in 1964. Researchers<br/>at Berkeley discovered Unq-257 and Unq-258 in 1964.<br/>
unnilseptium	unnilseptium<br/>Symbol:<br/>Atomic number: 107<br/>Atomic weight: (262)<br/>Radioactive transition metal. Half-life of approximately 1/500 s.<br/>Discovered by the Joint Institute for Nuclear Research at Dubna (U.S.S.R.)<br/>in 1976. Confirmed by West German physicists at the Heavy Ion Research<br/>Laboratory at Darmstadt.<br/>
unnilunium	unnilunium<br/>Symbol: Unu<br/>Name proposed by the {IUPAC} to settle the dispute over naming the 101st<br/>element {mendelevium}.<br/>
uranium	uranium<br/>Symbol: U<br/>Atomic number: 92<br/>Atomic weight: (231)<br/>White radioactive metallic element belonging to the actinoids. Three<br/>natural isotopes, U-238, U-235 and U-234. Uranium-235 is used as the fuel<br/>for nuclear reactors and weapons. Discovered by Martin H. Klaproth in 1789.<br/>
vanadium	vanadium<br/>Symbol: V<br/>Atomic number: 23<br/>Atomic weight: 50.9415<br/>Soft and ductile, bright white metal. Good resistance to corrosion by<br/>alkalis, sulphuric and hydrochloric acid. It oxidizes readily about<br/>933K. There are two naturally occurring isotopes of vanadium, and 5<br/>radioisotopes, V-49 having the longest half-life at 337 days. Vanadium<br/>has nuclear applications, the foil is used in cladding titanium to steel,<br/>and vanadium-gallium tape is used to produce a superconductive magnet.<br/>Originally discovered by Andres Manuel del Rio of Mexico City in 1801.<br/>His discovery went unheeded, however, and in 1820, Nils Gabriel Sefstron<br/>of Sweden rediscovered it. Metallic vanadium was isolated by Henry Enfield<br/>Roscoe in 1867. The name vanadium comes from {Vanadis}, a goddess of<br/>Scandinavian mythology. Silvery-white metallic transition element.<br/>Vanadium is essential to {ascidian}s. Rats and chickens are also known<br/>to require it. Metal powder is a fire hazard, and vanadium compounds<br/>should be considered highly toxic. May cause lung cancer if inhaled.<br/>
wolfram	wolfram<br/>Original name for {tungsten}.<br/>
xenon	xenon<br/>Symbol: Xe<br/>Atomic number: 54<br/>Atomic weight: 131.30<br/>Colourless, odourless gas belonging to group 18 on the periodic table (the<br/>noble gases.) Nine natural isotopes and seven radioactive isotopes are<br/>known. Xenon was part of the first noble-gas compound synthesized.<br/>Several others involving Xenon have been found since then. Xenon was<br/>discovered by Ramsey and Travers in 1898.<br/>
ytterbium	ytterbium<br/>Symbol: Yb<br/>Atomic number: 70<br/>Atomic weight: 173.04<br/>Silvery metallic element of the lanthanoids. Seven natural isotopes and<br/>ten artificial isotopes are known.  Used in certain steels. Discovered by<br/>J.D.G. Marignac in 1878.<br/>
yttrium	yttrium<br/>Symbol: Y<br/>Atomic number: 39<br/>Atomic weight: 88.905<br/>Silvery-grey metallic element of group 3 on the periodic table. Found in<br/>uranium ores. The only natural isotope is Y-89, there are 14 other<br/>artificial isotopes. Chemically resembles the lanthanoids. Stable in the<br/>air below 400 degrees, celsius. Discovered in 1828 by Friedrich Wohler.<br/>
zinc	zinc<br/>Symbol: Zn<br/>Atomic number: 30<br/>Atomic weight: 65.38<br/>Blue-white metallic element. Occurs in multiple compounds naturally. Five<br/>stable isotopes are six radioactive isotopes have been found. Chemically a<br/>reactive metal, combines with oxygen and other non-metals, reacts with<br/>dilute acids to release hydrogen.<br/>
zirconium	zirconium<br/>Symbol: Zr<br/>Atomic number: 40<br/>Atomic weight: 91.22<br/>Grey-white metallic transition element. Five natural isotopes and six<br/>radioactive isotopes are known. Used in nuclear reactors for a {neutron}<br/>absorber. Discovered in 1789 by Martin Klaproth, isolated in 1824 by<br/>Berzelius.<br/>