Periodic Table of The Elements

Name: Hydrogen
Symbol: H
Atomic Number: 1
Atomic Mass: 1.0079
Atomic Volume: 11.212 cc/mol
Discovered By: Cavendish
Discovery Date: 1766
Origin of Name: Hydrogen - (Greek) Hydro (water) and genes (forming), named by Lavoisie
Toxicity: Not toxic. Has narcotic effect at very high pressures.
Summary: Hydrogen is found as a diatomic gas (H₂). H₂ is a lighter-than-air, flammable gas. It burns with an almost invisible flame to form water. Only trace amounts of H₂ are found in the atmosphere, most H₂ has long since floated out of the atmosphere. However, hydrogen is one of the main components of stars and is thought to make up 90% of the atoms in the universe.

Name: Helium
Symbol: He
Atomic Number: 2
Atomic Mass: 4.0026
Atomic Volume: 19.43 cc/mol
Discovered By: Janssen, Ramsay
Discovery Date: First detected in the spectrum of the sun by Janssen during a solar eclipse in 1868. It was isolated by Ramsay in 1895.
Origin of Name: Helium - (Greek) Helios (Sun)
Toxicity: Not toxic. Has narcotic effect at very high pressure (103 kN/m²).
Summary: Helium is an inert gas. It is lighter than air, but somewhat heavier than hydrogen. One cu. ft. of He will lift 0.0685 lb. (0.0311 Kg) at 0° C and 1 atm. Helium does not exist in the solid form at 1 atm pressure; it remains liquid to 0°K. It can be solidified only at higher pressures. One form of liquid helium is a superfluid and has almost zero viscosity. It will flow up and out of a beaker containing it. Most of the atmospheric He has floated out into space. However, He is obtained commercially from natural gas wells.

Name: Lithium
Symbol: Li
Atomic Number: 3
Atomic Mass: 6.939
Atomic Volume: 12.94 cc/mol
Discovered By: Artvedson
Discovery Date: 1817
Origin of Name: Lithium (Greek) - Lithos (stone)
Toxicity: Not toxic. Compounds are not toxic. Lithium hydroxide acts on an organism in the same way as all alkalis. See sodium.
Summary: Lithium is the lightest of the metals, and would float on water. However, lithium reacts with water to form lithium hydroxide. Li is not found free in nature.

Name: Beryllium
Symbol: Be
Atomic Number: 4
Atomic Mass: 9.0122
Atomic Volume: 4.89 cc/mol
Discovered By: Wöhler and Bussy
Discovery Date: 1828
Origin of Name: Beryllium - (Greek) berryllos (beryl), also called Glucinium or Glucinum (Greek) glykys (sweet)
Toxicity: Highly toxic, especially in finely dispersed form. Soluble compounds are highly toxic. Beryllium oxide is very toxic. Produces a chronic disease - berylliosis.
Summary: Extremely toxic metal. Emerald and Aquamarine are precious forms of beryllium.

Name: Boron
Symbol: B
Atomic Number: 5
Atomic Mass: 10.811 +/- 0.003
Atomic Volume: 4.67 cc/mol
Discovered By: First isolated by Sir Humphrey Davy in 1808
Discovery Date: 1808
Origin of Name: Boron - (Arabic) Buraq
Toxicity: Not toxic. Finely dispersed powder has a harmful effect on the lungs. Compounds not toxic. Fatal when taken internally in large amounts (5-20 g). Some compounds such as chromium boride are toxic (finely dispersed insoluble powders).
Summary: Boron is not found free in nature, but usually as borates such as borax (Na₂B₄O₇). Pure Boron crystals (alpha-tetragonal) are almost as hard as diamond.

Name: Carbon
Symbol: C
Atomic Number: 6
Atomic Mass: 12.01115
Atomic Volume: 3.42 cc/mol
Discovered By: Prehistoric discovery
Discovery Date: Prehistoric discovery
Origin of Name: Carbon - (Latin) carbo (charcoal)
Toxicity: Not toxic. Finely dispersed dust produces pulmonary fibrosis. Carbon compounds do not have common features of physiological action, and their characteristics cannot be given in a general form.
Summary: Carbon has four distinct forms:

Diamond - clear crystal, cubic (tetrahedral), melting point = 3770 K, boiling point = 4200 K, density = 3.5153
Graphite - black, hexagonal, melting point = 4300 K at 63.5 atm, boiling point = 4200 K, density = 2.267
Amorphous - black, sublimes at 3920 K, density = 1.8 - 2.1
Fullerenes - closed shells of carbon atoms, common examples are C₆₀ and C₇₀.

Carbon is the basis of organic chemistry. All life on earth is made primarily of carbon compounds. All forms of carbon (including diamond) will burn if heated. Diamond is one of the hardest materials. Graphite consists of sheets of fused hexagonal rings. The sliding of these sheets past each other give graphite its good lubricating properties.

Name: Nitrogen
Symbol: N
Atomic Number: 7
Atomic Mass: 14.0067
Atomic Volume: 13.70 cc/mol
Discovered By: First isolated by Rutherford in 1772
Discovery Date: 1772
Origin of Name: Nitrogen - (Greek) nitron (native soda), genes (forming)
Toxicity: Not toxic. Has narcotic action at high pressure (in mixture with oxygen). Dissolves in blood and tissues. Nitrogen leaving blood and tissues produces caisson disease.
Summary: Nitrogen gas (N₂) makes up 78% of the atmosphere by volume.

Name: Oxygen
Symbol: O
Atomic Number: 8
Atomic Mass: 15.9994
Atomic Volume: 10.89 cc/mol
Discovered By: First isolated by Priestley in 1774
Discovery Date: 1774
Origin of Name: Oxygen - (Greek) oxys (sharp, acid) genes (forming)
Toxicity: Not toxic. Excess oxygen under pressure leads to inflammatory process in the organism.
Summary: Oxygen gas (O₂) makes up 21% of the atmosphere by volume. Oxygen does not burn, but is necessary to support combustion. Higher concentrations of O₂ will cause faster and hotter combustion. This is the basis of the oxy-acetylene torch used for welding. Oxygen is essential for respiration of all plants and animals. Ozone (O₃) is another elemental form of oxygen. It is formed when O₂ is subjected to ultraviolet light or electric discharge. Its presence in the stratosphere is essential for absorbing UV light and preventing its reaching earth's surface.

Name: Fluorine
Symbol: F
Atomic Number: 9
Atomic Mass: 18.9984
Atomic Volume: 14.61 cc/mol
Discovered By: First isolated by Moisson in 1886
Discovery Date: 1886
Origin of Name: Fluorine - (Latin and French) fluere (flow or flux)
Toxicity: Toxic. Attacks respiratory tracts. Compounds are toxic, especially hydrofluoric acid and its salts (protoplasmic poisons). Hydrofluoric acid produces ulcers which are difficult to heal.
Summary: Fluorine is the most reactive element. Fluorine gas (F₂) will react with almost all substances. It will burn water and will react with some inert gases. Fluorine is the most electronegative element. Teflon (polytetrafluroethylene) is a polymer in which all the hydrogen atoms are replaced with fluorine atoms. Thus, Teflon will not further react with many compounds under normal conditions.

Name: Neon
Symbol: Ne
Atomic Number: 10
Atomic Mass: 20.183
Atomic Volume: 14.0 cc/mol
Discovered By: First isolated by Ramsay and Travers in 1898
Discovery Date: 1898
Origin of Name: Neon - (Greek) neos (new)
Toxicity: Not toxic.
Summary: Neon is an inert gas. It exists in the atmosphere at a concentration of 15 ppm. Neon is used in "neon" lights and has a orange-red color (other colors are produced by other gases).

Name: Sodium
Symbol: Na
Atomic Number: 11
Atomic Mass: 22.9898
Atomic Volume: 23.80 cc/mol
Discovered By: First isolated by Sir Humphrey Davy in 1807
Discovery Date: 1807
Origin of Name: Sodium - (English) soda, (Latin) sodanum (headache remedy), the symbol Na comes from Natrium (Latin)
Toxicity: Not toxic. Compounds are not toxic. Sodium hydroxide and sodium salts of weak acids (which, on hydrolysis, behave as alkalis) attack the skin.
Summary: Sodium is not found as the free element in Nature. Sodium floats on water and reacts violently with it, possibly igniting. It reacts with water to form hydrogen gas (H₂) and sodium hydroxide (NaOH). The most common compound of sodium is sodium chloride, NaCl, common table salt.

Name: Magnesium
Symbol: Mg
Atomic Number: 12
Atomic Mass: 24.312
Atomic Volume: 14.0 cc/mol
Discovered By: First isolated by Sir Humphrey Davy in 1808
Discovery Date: 1808
Origin of Name: Magnesium - (from Magnesia, a district in Greece)
Toxicity: Not toxic. Magnesium vapor on inhalation produces foundry fever. See zinc.
Summary: Magnesium is not found free in nature. Magnesium will ignite upon heating in air and will burn with a brilliant white flame. Magnesium hydroxide, Mg(OH)₂, (Milk of Magnesia) and magnesium sulfate (Epsom salts) are used in medicine.

Name: Aluminum
Symbol: Al
Atomic Number: 13
Atomic Mass: 26.9815
Atomic Volume: 10.0 cc/mol
Discovered By: Wöhler
Discovery Date: 1827
Origin of Name: Aluminum - (Latin) alumen, alum (alum, a compound of aluminum, AlKS₂O₈ 10H₂O)
Toxicity: Not toxic. Dust of finely dispersed aluminum is toxic. Compounds are not toxic.
Summary: Aluminum is the most abundant metal in the earth's crust (8.1%), but is not found in Nature as the free metal. Aluminum metal is coated with a thin film of aluminum oxide (Al₂O₃) which prevents further corrosion. Aluminum was very expensive before 1886 when a convenient method of obtaining aluminum metal from the ore was discovered. Aluminum is known as aluminium in countries other than the USA.

Name: Silicon
Symbol: Si
Atomic Number: 14
Atomic Mass: 28.086
Atomic Volume: 12.04 cc/mol
Discovered By: First isolated by Berzelius in 1824
Discovery Date: 1824
Origin of Name: Silicon - (Latin) silex, silicis (flint)
Toxicity: Not toxic. Finely dispersed dust produces pulmonary fibrosis. Silicon compounds do not have common features of physiological action, and their characteristics cannot be given in a general form. SiO₂ produces silicosis - "dust disease".
Summary: Silicon is not found free in Nature, but mainly as the dioxide, SiO₂, also called silica. Silicon is the second most abundant element in the earth's crust (25.7% by weight), surpassed only by oxygen. Silica is the main component of sand. Crystalline silica is quartz. Amorphous silica, often with added ingredients, is glass. Silicon is a poor conductor of electricity, but when doped with small amounts of other elements, its conductivity increases several orders of magnitude to a level between insulators and conductors. Doped silicon is called a semiconductor. Silicon is the basis of the semiconductor industry.

Name: Phosphorus
Symbol: P
Atomic Number: 15
Atomic Mass: 30.9738
Atomic Volume: 13.93 cc/mol
Discovered By: First isolated by Brand in 1669
Discovery Date: 1669
Origin of Name: Phosphorus - (Greek) phosphoros (light-bearing)
Toxicity: Yellow phosphorus is highly toxic; red has low toxicity. The inhalation of red phosphorus dust is as dangerous and has the same action as the inhalation of white phosphorus dust. Phosphine is particularly dangerous. It attacks the central nervous system and disturbs the blood circulation.
Summary: Phosphorus has three forms:

White - cubic crystals of P₄, melting point = 317.4 K, boiling point = 553.5 K, density = 1.828
Black - orthorhombic, density = 2.691
Red - red-violet powder, triclinic, sublimes at 689 K, density = 2.34

Phosphorus is not found free in nature, but usually as phosphates. Extremely toxic.

Name: Sulfur
Symbol: S
Atomic Number: 16
Atomic Mass: 32.064
Atomic Volume: 15.38 cc/mol
Discovered By: Known since ancient times
Discovery Date: Known since ancient times
Origin of Name: Sulfur - (Sanskrit) sulvere, (Latin) sulphurium
Toxicity: Not toxic. Dust is harmful on inhalation and produces a disease of the lungs (thiopneumoconiosis). Hydrogen sulfide, sulfur dioxide, soluble sulfides, and other compounds are toxic.
Summary: Sulfur has three forms:

alpha - cycloocta-sulfur (S₈), amber, rhombic, melting point = 388.36 K, density = 2.02
beta - cycloocta-sulfur (S₈), light yellow, monoclinic, melting point = 388.36 K, density = 1.96
gamma - yellow, monoclinic, boiling point = 379.95 K, density = 1.92

Pure element found near volcanoes and hot springs. Sulfur is also known as brimstone.

Name: Chlorine
Symbol: Cl
Atomic Number: 17
Atomic Mass: 35.453 +/- 0.001
Atomic Volume: 17.38 cc/mol
Discovered By: Scheele
Discovery Date: 1774
Origin of Name: Chlorine (Greek) chloros (greenish-yellow)
Toxicity: Toxic. Attacks the respiratory tract and leads to pulmonary edema. Hydrogen chloride and chlorinated hydrocarbons are toxic. Alkali metal chlorides are not toxic in small amounts.
Summary: Chlorine is not found free in nature, but mainly as sodium chloride. Chlorine is a diatomic gas (Cl₂).

Name: Argon
Symbol: Ar
Atomic Number: 18
Atomic Mass: 39.948
Atomic Volume: 24.12 cc/mol
Discovered By: Lord Rayleigh and Ramsay
Discovery Date: 1894
Origin of Name: Argon - (Greek) argos (inactive)
Toxicity: ???
Summary: Argon is an inert gas. Argon makes up 0.94% of the atmosphere.

Name: Potassium
Symbol: K
Atomic Number: 19
Atomic Mass: 39.102
Atomic Volume: 43.50 cc/mol
Discovered By: First isolated by Sir Humphrey Davy in 1807
Discovery Date: 1807
Origin of Name: Potassium - (English) Potash, the symbol K comes from (Latin) kalium
Toxicity: Not toxic. See sodium.
Summary: Potassium is not found free in Nature. It ignites spontaneously in contact with water, and rapidly oxidizes in air.

Name: Calcium
Symbol: Ca
Atomic Number: 20
Atomic Mass: 40.08
Atomic Volume: 26.20 cc/mol
Discovered By: Sir Humphrey Davy
Discovery Date: 1808
Origin of Name: Calcium - (Latin) calx (lime)
Toxicity: Not toxic. Compounds are normally not toxic. Calcium hydroxide and calcium oxide act as irritants, producing burns.
Summary: Never found free in Nature. Essential component in shells, bones, and teeth. Also found in limestone, marble, and cement.

Name: Scandium
Symbol: Sc
Atomic Number: 21
Atomic Mass: 44.956
Atomic Volume: 15.06 cc/mol
Discovered By: Predicted by Mendeleev on the basis of his Periodic Table and called "Ekaboron". Isolated by Nilson in 1876.
Discovery Date: 1876
Origin of Name: Scandium - (Latin) Scandia (Scandinavia)
Toxicity: Character of toxicity not established.
Summary: A rare earth metal. Responsible for the blue color in aquamarine.

Name: Titanium
Symbol: Ti
Atomic Number: 22
Atomic Mass: 47.90
Atomic Volume: 10.63 cc/mol
Discovered By: First isolated by Gregor in 1789
Discovery Date: 1789
Origin of Name: Titanium - (Latin) Titans (the first sons of the Earth in Roman mythology)
Toxicity: Not toxic. In finely dispersed state evidently has a fibrogenic action. Titanium dioxide is not toxic.
Summary: Not found free in Nature. Titanium will burn in air, and will burn in an atmosphere of nitrogen under some conditions. Titanium Dioxide (TiO₂) is a white powder used in paint.

Name: Vanadium
Symbol: V
Atomic Number: 23
Atomic Mass: 50.942
Atomic Volume: 8.36 cc/mol
Discovered By: First isolated by Sefström in 1830
Discovery Date: 1830
Origin of Name: Vanadium - Vanadis, Scandinavian Goddess
Toxicity: No evidence of toxicity; fibrogenic action of powdered vanadium is not definitely established. Compounds are toxic.
Summary: Used in manufacture of rust-resistant vanadium steel.

Name: Chromium
Symbol: Cr
Atomic Number: 24
Atomic Mass: 51.996
Atomic Volume: 7.23 cc/mol
Discovered By: Vauquelin
Discovery Date: 1797
Origin of Name: Chromium - (Greek) chroma (color)
Toxicity: Finely dispersed chromium is toxic on inhalation, as are chromium compounds. Compounds of hexavalent chromium, chromates, and bichromates are most toxic.
Summary: Not found free in nature. Chromium is used for decorative coatings because it is not oxidized by air.

Name: Manganese
Symbol: Mn
Atomic Number: 25
Atomic Mass: 54.9381
Atomic Volume: 7.36 cc/mol
Discovered By: First isolated by Gahn in 1774
Discovery Date: 1774
Origin of Name: Manganese - (Latin) magnes (magnet, from magnetic properties of pyrolusite, an ore)
Toxicity: Finely dispersed metallic manganese is toxic. Compounds are poisonous and attack the central nervous system.
Summary: Manganese is responsible for the purple color of amethyst.

Name: Iron
Symbol: Fe
Atomic Number: 26
Atomic Mass: 55.847
Atomic Volume: 7.09 cc/mol
Discovered By: Prehistoric
Discovery Date: The discovery of iron is prehistoric. The iron age began in Europe around 800 BC.
Origin of Name: Iron - (Anglo-Saxon) iron, the symbol Fe is from (Latin) ferrum (iron)
Toxicity: Not toxic; in dust form it has a fibrogenic action. Iron salts normally do not produce industrial poisoning.
Summary: Second most abundant element in Earth's crust (5%). The earth's core is thought to consist mainly of iron. Iron is found in hemoglobin used to carry oxygen in red blood cells. Iron is magnetic, and magnetite is a naturally-occurring magnetic ore. Iron is readily oxidized by moist air into iron oxide (rust).

Name: Cobalt
Symbol: Co
Atomic Number: 27
Atomic Mass: 58.9332
Atomic Volume: 6.70 cc/mol
Discovered By: Brandt
Discovery Date: 1735
Origin of Name: Cobalt - (German) Kobald (gremlin or evil spirit), (Greek) cobalos (mine)
Toxicity: Finely dispersed cobalt dust is partly toxic (produces changes in the lungs). Cobalt compounds are toxic in large amounts.
Summary: Cobalt-60 is used as a gamma ray source. Cobalt produces a dark blue color in glass.

Name: Nickel
Symbol: Ni
Atomic Number: 28
Atomic Mass: 58.71
Atomic Volume: 6.60 cc/mol
Discovered By: First isolated by Cronstedt in 1751
Discovery Date: 1751
Origin of Name: Nickel - (German) Nickel (Satan, or "Old Nick") and Kupfernickel (Old Nick's copper)
Toxicity: Finely dispersed nickel dust is toxic; attacks the lungs, produces chronic poisoning. Nickel salts produce "nickel eczema." Nickel carbonyl is highly toxic.
Summary: Used extensively as a catalyst, and in making stainless steels and other alloys. American five-cent pieces no longer contain nickel.

Name: Copper
Symbol: Cu
Atomic Number: 29
Atomic Mass: 63.54
Atomic Volume: 7.11 cc/mol
Discovered By: Prehistoric
Discovery Date: The discovery of copper is prehistoric. The Bronze Age predates the Iron Age.
Origin of Name: Copper - (Latin) Cuprum (from the island of Cyprus), the symbol Cu also comes from Cuprum
Toxicity: Toxicity analogous to the toxicity of nickel powder. Toxicity of pure copper salts is slight.
Summary: Copper is found as the native metal, as well as in a number of ores. Bronze (copper-tin) and brass (copper-zinc) are copper alloys. All American coins are made of copper alloys.

Name: Zinc
Symbol: Zn
Atomic Number: 30
Atomic Mass: 65.37
Atomic Volume: 9.15 cc/mol
Discovered By: Zinc metal was produced in India in the 13th century and rediscovered by Marggraf in 1746
Discovery Date: 1746
Origin of Name: Zinc - (German) Zink (of obscure origin)
Toxicity: Not toxic in compact form. Zinc oxide vapor is toxic, produces "foundry fever." Toxicity of zinc salts is slight.
Summary: Used in the production of brass, a copper-zinc alloy. Zinc oxide (ZnO) is used as a sunscreen. Zinc ores were used in ancient times to produce brass.

Name: Gallium
Symbol: Ga
Atomic Number: 31
Atomic Mass: 69.72
Atomic Volume: 11.80 cc/mol
Discovered By: Lecoq de Boisbaudran
Discovery Date: 1875
Origin of Name: Gallium - (Latin) Gallia (France)
Toxicity: Hardly toxic. Compounds (especially soluble compounds) are toxic; they surpass mercury and arsenic in toxicity.
Summary: Predicted by Mendeleev using his Periodic Table and named "ekaaluminum". Gallium is liquid just above room temperature (melting point 29.78 °C). Gallium expands by more than 3% on freezing. Gallium Arsenide is an important semiconductor material.

Name: Germanium
Symbol: Ge
Atomic Number: 32
Atomic Mass: 72.59
Atomic Volume: 13.64 cc/mol
Discovered By: First isolated by Winkler in 1886
Discovery Date: 1886
Origin of Name: Germanium - (Latin) Germania (Germany)
Toxicity: Compounds are slightly toxic.
Summary: Predicted by Mendeleev using his Periodic Table and named "ekasilicon". Germanium is an important semiconductor material.

Name: Arsenic
Symbol: As
Atomic Number: 33
Atomic Mass: 74.9216
Atomic Volume: 12.98 cc/mol
Discovered By: Isolated by Albertus Magnus in 1250
Discovery Date: 1250
Origin of Name: Arsenic - (Latin) arsenicum, (Greek) arsenikon (yellow orpiment (As₂O₃) identified with arsenikos (male) in the belief that metals were different sexes) (Arabic) az-zernikh (the orpiment from Persian zerni-zar (gold))
Toxicity: Elementary arsenic is not toxic in pure form. Compounds are highly toxic.
Summary: Found to a small extent as the element, mostly as arsenides of metals. Most compounds containing arsenic are poisonous. Gallium arsenide is an important semiconductor material.

Name: Selenium
Symbol: Se
Atomic Number: 34
Atomic Mass: 78.96
Atomic Volume: 16.42 cc/mol
Discovered By: Berzelius
Discovery Date: 1817
Origin of Name: Selenium - (Greek) Selene (moon)
Toxicity: Elementary selenium is less toxic than its compounds. Compounds are toxic, action is similar in character to that of arsenic.
Summary: Three forms:

Amorphous: Red-black, melting point = 343 K, density = 4.26, Therm. cond. = 0.00519
Crystalline: Red, monoclinic, melting point = 443 K, density = 4.48
Metallic: Gray-black, hexagonal, melting point = 490 K, density = 4.48

Used in photocopy toner. Selenium is a poor electrical conductor in the dark. When exposed to light, it becomes conductive.

Name: Bromine
Symbol: Br
Atomic Number: 35
Atomic Mass: 79.909
Atomic Volume: 19.61 cc/mol
Discovered By: First isolated by Balard in 1826
Discovery Date: 1826
Origin of Name: Bromine - (Greek) bromos (stench)
Toxicity: Toxic like chlorine, but slightly weaker.
Summary: Bromine is the only non-metallic element that is liquid at room temperature. Bromine is not found free in nature, but usually as the bromide. Bromine liquid or gas (Br₂) is severely irritating and toxic.

Name: Krypton
Symbol: Kr
Atomic Number: 36
Atomic Mass: 83.80
Atomic Volume: 27.90 cc/mol
Discovered By: Ramsay and Travers
Discovery Date: 1898
Origin of Name: Krypton - (Greek) kryptos (hidden)
Toxicity: Not toxic. Has narcotic action at high concentration and pressure.
Summary: A noble gas. However, KrF₂, krypton difluoride, has been prepared.

Name: Rubidium
Symbol: Rb
Atomic Number: 37
Atomic Mass: 85.47
Atomic Volume: 55.48 cc/mol
Discovered By: Bunsen and Kirchoff
Discovery Date: 1861
Origin of Name: Rubidium - (Latin) rubidius (deepest red)
Toxicity: No information available.
Summary: Not found free in nature. The chemical properties of rubidium resembles those of potassium. Ignites spontaneously in oxygen.

Name: Strontium
Symbol: Sr
Atomic Number: 38
Atomic Mass: 87.62
Atomic Volume: 33.35 cc/mol
Discovered By: Sir Humphrey Davy
Discovery Date: 1808
Origin of Name: Strontium - (Strontian, town in Scotland)
Toxicity: Toxic. Salts and compounds are toxic like barium slats; produce paralysis. Strontium oxide produces deep lesions of the eyes.
Summary: Not found free in Nature. Finely divided strontium ignites spontaneously in air. Strontium-90 is a radioactive isotope found in nuclear fallout. It is absorbed into the body and is a health hazard.

Name: Yttrium
Symbol: Y
Atomic Number: 39
Atomic Mass: 88.905
Atomic Volume: 19.88 cc/mol
Discovered By: Gadolin
Discovery Date: 1794
Origin of Name: Yttrium - Ytterby, a village in Sweden. Four elements are named for Ytterby: Yttrium, Ytterbium, Terbium, and Erbium
Toxicity: See lanthanoids.
Summary: A rare earth metal. Yttrium is used in making lasers.

Name: Zirconium
Symbol: Zr
Atomic Number: 40
Atomic Mass: 91.22
Atomic Volume: 13.97 cc/mol
Discovered By: Klaproth
Discovery Date: 1789
Origin of Name: Zirconium - (Arabic) zargun (gold color, from the gemstone zircon)
Toxicity: Powdered zirconium is not toxic. Compounds are almost nontoxic.
Summary: Zirconium can absorb large amounts of oxygen from the air. Zirconium oxide (ZrO₂, zirconia) in its crystalline form is used as a gem material.

Name: Niobium
Symbol: Nb
Atomic Number: 41
Atomic Mass: 92.906
Atomic Volume: 10.76 cc/mol
Discovered By: Hatchett
Discovery Date: 1801
Origin of Name: Niobium - Niobe, daughter of Tantalus
Toxicity: Apparently not toxic. There are data indicating toxicity for potassium niobate.
Summary: Not found free in Nature. Niobium is used in many alloys with iron. Niobium is also known as Columbium from Columbia, a name for America. The accepted name is Niobium, but the metal is often referred to as Columbium in the USA.

Name: Molybdenum
Symbol: Mo
Atomic Number: 42
Atomic Mass: 95.94
Atomic Volume: 9.39 cc/mol
Discovered By: Scheele (First isolated as a metal by Hjelm in 1782)
Discovery Date: 1778
Origin of Name: Molybdenum - (Greek) molybdos (lead)
Toxicity: Metallic molybdenum is of low toxicity. The inhalation of molybdenum dust by animals did not produce toxicosis in them. Molybdenum trioxide and molybdates are toxic.
Summary: Not found free in nature. Molybdenum has a very high melting point. Used in ferrous and non-ferrous alloys.

Name: Technetium
Symbol: Tc
Atomic Number: 43
Atomic Mass: (98)
Atomic Volume: ??? cc/mol
Discovered By: First produced by E. Lawrence and isolated by Perrier and Segre in 1937
Discovery Date: 1937
Origin of Name: Technetium - (Greek) technetos (artificial)
Toxicity: ???
Summary: Technetium is not found naturally on Earth. It was the first artificially produced element by bombarding molybdenum with deuterons. It has also been observed in the spectrum of the sun and stars.

Name: Ruthenium
Symbol: Ru
Atomic Number: 44
Atomic Mass: 101.07
Atomic Volume: 8.13 cc/mol
Discovered By: First isolated by Klaus in 1844
Discovery Date: 1844
Origin of Name: Ruthenium - (Latin) Ruthenia (Russia)
Toxicity: No information available.
Summary: A member of the Platinum group. Ruthenium is found both native and in ores. Used in alloys to harden metals for jewelry and pen nibs.

Name: Rhodium
Symbol: Rh
Atomic Number: 45
Atomic Mass: 102.905
Atomic Volume: 8.28 cc/mol
Discovered By: Wollaston
Discovery Date: 1803
Origin of Name: Rhodium - (Greek) rhodon (rose)
Toxicity: No information available about the elemental form. Compounds have low toxicity.
Summary: A member of the Platinum group. Rhodium is found both native and in ores. One of the rarest elements, only about 10-7% of the earth's crust.

Name: Palladium
Symbol: Pd
Atomic Number: 46
Atomic Mass: 106.4
Atomic Volume: 8.84 cc/mol
Discovered By: Wollaston
Discovery Date: 1803
Origin of Name: Palladium - named after the asteroid Pallas, discovered about the same time, (Greek) Pallas, goddess of wisdom
Toxicity: Apparently not toxic.
Summary: A member of the platinum group. Found free in nature alloyed with platinum, and in ores. Palladium has the ability to absorb 900 times its volume of hydrogen gas (H₂). This effect was thought to be the basis of cold fusion. Used as a catalyst, and when alloyed with gold, to make white gold for jewelry.

Name: Silver
Symbol: Ag
Atomic Number: 47
Atomic Mass: 107.870
Atomic Volume: 10.27 cc/mol
Discovered By: Prehistoric
Discovery Date: Silver has been known since ancient times (earlier than 3000 BC)
Origin of Name: Silver - (Anglo-Saxon ) Seolfor (silver). The symbol Ag is from (Latin) argtenum (silver)
Toxicity: Not toxic. Silver nitrate acts as irritant, produces argyria (deposition of silver in tissues).
Summary: Silver occurs native and in ores. Silver halide salts are light-sensitive, and are the basis of photographic film.

Name: Cadmium
Symbol: Cd
Atomic Number: 48
Atomic Mass: 112.40
Atomic Volume: 13.01 cc/mol
Discovered By: Stromeyer
Discovery Date: 1817
Origin of Name: Cadmium - (Latin) cadmia, (Greek) kadmeia (ancient name for calamine, zinc carbonate)
Toxicity: Metallic cadmium itself is not toxic. Compounds are very toxic.
Summary: Not found free in nature. Cadmium is used in nickel-cadmium rechargeable batteries. Discovered by Stromeyer in 1817 as an impurity in zinc carbonate.

Name: Indium
Symbol: In
Atomic Number: 49
Atomic Mass: 114.82
Atomic Volume: 15.76 cc/mol
Discovered By: Reich and Richter
Discovery Date: 1863
Origin of Name: Indium - from its bright indigo spectral line
Toxicity: Metallic indium is apparently not toxic. No data on poisoning or diseases caused by compounds. Indium compounds stimulate hair growth.
Summary: Not found free in nature. Indium makes a high-pitched cry when bent. Used in the semiconductor industry in transistors and photoconductors.

Name: Tin
Symbol: Sn
Atomic Number: 50
Atomic Mass: 118.69
Atomic Volume: 16.29 cc/mol
Discovered By: Prehistoric
Discovery Date: Tin has been known since ancient times
Origin of Name: Tin - (Anglo-Saxon) tin (tin), the symbol Sn comes from (Latin) stannum (tin)
Toxicity: Not toxic. Prolonged action of tin oxide dust produces a "dust" disease of the lungs. Tin compounds are apparently not toxic.
Summary: Not found free in nature. Tin has two crystalline structures. Ordinary or white tin has a hexagonal structure. When cooled below 13.2°C, it slowly changes into the useless gray tin form (tetragonal). Tin emits a high-pitched "tin cry" when bent. Tin is used in coating steel cans for corrosion resistance. Alloys of tin are also used in solder, bronze, and pewter.

Name: Antimony
Symbol: Sb
Atomic Number: 51
Atomic Mass: 121.75
Atomic Volume: 18.19 cc/mol
Discovered By: First described as a metal by Thölde in 1604
Discovery Date: 1604
Origin of Name: Antimony - (Latin) antimonium, the symbol Sb is from (Latin) stibium (mark)
Toxicity: Antimony vapor and its dust are toxic. Compounds are toxic, but less than arsenic compounds.
Summary: Found native and in ores. Antimony is used in alloys and in the semiconductor industry. Antimony and many of its compounds are toxic.

Name: Tellurium
Symbol: Te
Atomic Number: 52
Atomic Mass: 127.60
Atomic Volume: 20.02 cc/mol
Discovered By: Discovered by Müller von Reichenstein in 1782, isolated and named by Klaproth in 1798
Discovery Date: 1782
Origin of Name: Tellurium - (Latin) tellus (earth)
Toxicity: Hardly toxic. Compounds are toxic, but less than selenium compounds.
Summary: Sometimes found native, but usually as the telluride of gold. Tellurium is used in the semiconductor industry. The town of Telluride, Colorado was once a source of tellurium.

Name: Iodine
Symbol: I
Atomic Number: 53
Atomic Mass: 126.9004
Atomic Volume: 25.72 cc/mol
Discovered By: Courtois
Discovery Date: 1811
Origin of Name: Iodine - (Greek) iodes (violet)
Toxicity: Toxic, produces dermatitis; vapor (see chlorine) attacks mucous membranes producing pulmonary edema.
Summary: Not found free in nature, but as various iodides. Iodine volatilizes when moderately heated to a purple gas. Iodine is necessary for proper thyroid function. Lack of it causes goiter. A small amount of potassium iodide (KI) is added to table salt to deliver dietary iodine. Tincture of iodine used as an antiseptic is a solution of iodine and KI in alcohol.

Name: Xenon
Symbol: Xe
Atomic Number: 54
Atomic Mass: 131.30
Atomic Volume: 36.76 cc/mol
Discovered By: Ramsay and Travers
Discovery Date: 1898
Origin of Name: Xenon - (Greek) xenon (stranger)
Toxicity: Not toxic. Has narcotic action (70% Xe).
Summary: A noble gas. Despite being a noble gas, many compounds of xenon have been prepared including XePtF₆, XeF₂, XeF₄, and XeO₃. Xenon is used in strobe lamps and flashlamps for photography.

Name: Cesium
Symbol: Cs
Atomic Number: 55
Atomic Mass: 132.905
Atomic Volume: 67.84 cc/mol
Discovered By: Bunsen and Kirchhoff
Discovery Date: 1860
Origin of Name: Cesium - (Latin) caesius (sky blue) (from its bright blue spectral lines)
Toxicity: No information available.
Summary: Not found free in Nature. Cesium is the most electropositive natural element. Reacts explosively with water. Cesium melts at just above room temperature. Cesium hydroxide is one of the strongest bases known.

Name: Barium
Symbol: Ba
Atomic Number: 56
Atomic Mass: 137.34
Atomic Volume: 38.21 cc/mol
Discovered By: Sir Humphrey Davy
Discovery Date: 1808
Origin of Name: Barium - (Greek) barys (heavy)
Toxicity: Toxic. Soluble salts are very toxic (produce paralysis of the heart); pure barium sulfate is not toxic. Barium carbonate is toxic.
Summary: Not found free in Nature. Oxidizes easily in air. All water-soluble barium compounds are poisonous.

Name: Lanthanum
Symbol: La
Atomic Number: 57
Atomic Mass: 138.91
Atomic Volume: 22.54 cc/mol
Discovered By: Mosander
Discovery Date: 1839
Origin of Name: Lanthanum - (Greek) lanthanein (to lie hidden)
Toxicity: Compounds are apparently toxic, but have not been studied adequately.
Summary: Not found free in nature. Lanthanum oxidizes easily in air and hot water. Lanthanum is used to make the alloy "misch metal" used in lighter flints.

Name: Cerium
Symbol: Ce
Atomic Number: 58
Atomic Mass: 140.12
Atomic Volume: 17.02 cc/mol
Discovered By: Klaproth and by Berzelius and Hisinger
Discovery Date: 1803
Origin of Name: Cerium - named for the asteroid Ceres, which was discovered about the same time
Toxicity: ???
Summary: Not found free in Nature. The most abundant rare earth element. Cerium is oxidized by water.

Name: Praseodymium
Symbol: Pr
Atomic Number: 59
Atomic Mass: 140.907
Atomic Volume: 20.82 cc/mol
Discovered By: First isolated (along with neodymium) by von Welsbach in 1885
Discovery Date: 1885
Origin of Name: Praseodymium - (Greek) prasios (green) and didymos (twin)
Toxicity: ???
Summary: A rare earth lanthanide. Used in lighter flints and welders' goggles. Praseodymium is the only element whose name contains A, E, I, O, U, and Y.

Name: Neodymium
Symbol: Nd
Atomic Number: 60
Atomic Mass: 144.24
Atomic Volume: 20.58 cc/mol
Discovered By: First isolated (along with praseodymium) by von Welsbach in 1885
Discovery Date: 1885
Origin of Name: Neodymium - (Greek) neos (new) and didymos (twin)
Toxicity: ???
Summary: A rare earth lanthanide. Used in lighter flints, and in laser rods. Oxidizes in air.

Name: Promethium
Symbol: Pm
Atomic Number: 61
Atomic Mass: (145)
Atomic Volume: ??? cc/mol
Discovered By: First manufactured by Law in 1941
Discovery Date: 1941
Origin of Name: Promethium - named for Prometheus, who stole fire from heaven in Roman mythology
Toxicity: ???
Summary: Not found naturally on earth. First predicted by Branner in 1902. Manufactured by nuclear bombardment.

Name: Samarium
Symbol: Sm
Atomic Number: 62
Atomic Mass: 150.35
Atomic Volume: 19.95 cc/mol
Discovered By: Lecoq de Boisbaudran
Discovery Date: 1879
Origin of Name: Samarium - from the mineral samarskite, named after Colonel Samarski, a Russian mine official
Toxicity: ???
Summary: A rare earth lanthanide. Samarium-cobalt alloy (SmCo₅) is an extremely magnetic metal.

Name: Europium
Symbol: Eu
Atomic Number: 63
Atomic Mass: 151.96
Atomic Volume: 28.97 cc/mol
Discovered By: Demarcay
Discovery Date: 1901
Origin of Name: Europium - named after Europe
Toxicity: ???
Summary: A rare earth lanthanide. Used in color TV phosphors.

Name: Gadolinium
Symbol: Gd
Atomic Number: 64
Atomic Mass: 157.25
Atomic Volume: 19.94 cc/mol
Discovered By: First isolated by Marignac in 1880
Discovery Date: 1880
Origin of Name: Gadolinium - from the mineral gadolinite, named after the Finnish chemist Gadolin
Toxicity: ???
Summary: A rare earth lanthanide. Used for color TV phosphors.

Name: Terbium
Symbol: Tb
Atomic Number: 65
Atomic Mass: 158.924
Atomic Volume: 19.25 cc/mol
Discovered By: First isolated by Mosander in 1843
Discovery Date: 1843
Origin of Name: Terbium - Ytterby, a village in Sweden. Four elements are named for Ytterby: Yttrium, Ytterbium, Terbium, and Erbium
Toxicity: ???
Summary: A rare earth lanthanide.

Name: Dysprosium
Symbol: Dy
Atomic Number: 66
Atomic Mass: 162.50
Atomic Volume: 18.98 cc/mol
Discovered By: Lecoq de Boisbaudran
Discovery Date: 1886
Origin of Name: Dysprosium - (Greek) dysprositos (hard to get at)
Toxicity: ???
Summary: A rare earth lanthanide.

Name: Holmium
Symbol: Ho
Atomic Number: 67
Atomic Mass: 164.930
Atomic Volume: 18.74 cc/mol
Discovered By: First isolated by Cleve in 1879
Discovery Date: 1879
Origin of Name: Holmium - named after Stockholm
Toxicity: ???
Summary: A rare earth lanthanide.

Name: Erbium
Symbol: Er
Atomic Number: 68
Atomic Mass: 167.26
Atomic Volume: 18.46 cc/mol
Discovered By: First isolated in 1934 by Klemm and Bommer
Discovery Date: 1934
Origin of Name: Erbium - Ytterby, a village in Sweden. Four elements are named for Ytterby: Yttrium, Ytterbium, Terbium, and Erbium
Toxicity: ???
Summary: A rare earth lanthanide. Used as a pink colorant for glass and porcelein glazes.

Name: Thulium
Symbol: Tm
Atomic Number: 69
Atomic Mass: 168.934
Atomic Volume: 18.13 cc/mol
Discovered By: Cleve
Discovery Date: 1879
Origin of Name: Thulium - Thule, an early name for Scandinavia
Toxicity: ???
Summary: A rare earth lanthanide.

Name: Ytterbium
Symbol: Yb
Atomic Number: 70
Atomic Mass: 173.04
Atomic Volume: 24.86 cc/mol
Discovered By: First isolated by Urbain in 1907
Discovery Date: 1907
Origin of Name: Ytterbium - Ytterby, a village in Sweden. Four elements are named for Ytterby: Yttrium, Ytterbium, Terbium, and Erbium
Toxicity: ???
Summary: A rare earth lanthanide. Ytterbium was once also called aldebaranium.

Name: Lutetium
Symbol: Lu
Atomic Number: 71
Atomic Mass: 174.97
Atomic Volume: 17.76 cc/mol
Discovered By: First isolated by Urbain in 1907
Discovery Date: 1907
Origin of Name: Lutetium - Lutetia, an ancient name for Paris
Toxicity: ???
Summary: A rare-earth lanthanide. Lutetium was also once called cassiopeium.

Name: Hafnium
Symbol: Hf
Atomic Number: 72
Atomic Mass: 178.49
Atomic Volume: 13.47 cc/mol
Discovered By: D. Coster and G. von Hevesy
Discovery Date: 1923
Origin of Name: Hafnium - Hafnia, Latin name for Copenhagen
Toxicity: ???
Summary: Not found free in Nature. Finely divided hafnium will ignite spontaneously in air (pyrophoric). Hafnium is very similar chemically to zirconium and is separated from it only with difficulty.

Name: Tantalum
Symbol: Ta
Atomic Number: 73
Atomic Mass: 180.948
Atomic Volume: 10.88 cc/mol
Discovered By: Ekeberg
Discovery Date: 1802
Origin of Name: Tantalum - (Greek) Tantalos (father of Niobe in Greek mythology)
Toxicity: Not toxic. No data available on the toxicity of tantalum compounds.
Summary: Not found free in Nature. Tantalum is often associated with niobium. Used for pen nibs, and medical instruments.

Name: Tungsten
Symbol: W
Atomic Number: 74
Atomic Mass: 183.85
Atomic Volume: 9.54 cc/mol
Discovered By:
Discovery Date:
Origin of Name: Tungsten - (Swedish) tung sten (heavy stone), the symbol W is from the German name for Tungsten, Wolfram, from the mineral wolframite
Toxicity: Powdered tungsten is toxic when inhaled as dust; produces irritation of the respiratory tract. Soluble tungstates are slightly toxic (irritate the skin).
Summary: Not found free in Nature. Tungsten has the highest melting point and lowest vapor pressure of all the metals. Used to harden steel and other alloys.

Name: Rhenium
Symbol: Re
Atomic Number: 75
Atomic Mass: 186.2
Atomic Volume: 8.85 cc/mol
Discovered By: Noddack, Tacke, and Berg
Discovery Date: 1925
Origin of Name: Rhenium - (Latin) Rhenus (Rhine)
Toxicity: Toxic action is not known. Soluble compounds are apparently not toxic.
Summary: Not found free in nature. Rhenium is very ductile, and has a high melting point and density.

Name: Osmium
Symbol: Os
Atomic Number: 76
Atomic Mass: 190.2
Atomic Volume: 8.42 cc/mol
Discovered By: Tennant
Discovery Date: 1803
Origin of Name: Osmium - (Greek) osme (a smell)
Toxicity: Apparently not toxic. Osmium tetroxide and other soluble compounds are toxic.
Summary: Found in platinum-bearing sands and in ores. Osmium, along with iridium, is one of the densest elements. Used to make hard alloys.

Name: Iridium
Symbol: Ir
Atomic Number: 77
Atomic Mass: 192.2
Atomic Volume: 8.84 cc/mol
Discovered By: Tennant
Discovery Date: 1803
Origin of Name: Iridium - (Latin) iris (rainbow, from its brightly colored salts)
Toxicity: No data available on toxicity.
Summary: Occurs as native metal in nature, usually alloyed with rhodium, platinum or gold. Iridium is the most corrosion resistant metal known.

Name: Platinium
Symbol: Pt
Atomic Number: 78
Atomic Mass: 195.09
Atomic Volume: 9.09 cc/mol
Discovered By: Discovered by Westerners in S. America by Ulloa in 1735, but platinum was used by pre-Colombian Indians
Discovery Date: 1735
Origin of Name: Platinum - (Spanish) platina (silver)
Toxicity: Not toxic. Platinum compounds are toxic (diseases of the skin).
Summary: Found native in nature, usually alloyed with other members of the platinum group, and in ores. Platinum does not corrode in air. Used for catalysts, in jewelry, and in scientific instruments. The standard meter bar in Paris, which was the standard metric length for many years, is an alloy of 10% iridium and 90% platinum.

Name: Gold
Symbol: Au
Atomic Number: 79
Atomic Mass: 196.967
Atomic Volume: 10.20 cc/mol
Discovered By: Prehistoric
Discovery Date: Gold has been known since ancient times
Origin of Name: Gold - (Sanskrit) jval (gold)
Toxicity: Not toxic. Soluble gold salts act as irritants on the skin.
Summary: Found native and in ores. Gold is extremely malleable (1 oz. of gold can be beaten out to a sheet 300 sq. ft. in area) and ductile (1 oz. can be drawn out into a wire over 60 miles long). Gold is not corroded by air. Used in jewelry, coinage, and to give red glass its color. Gold is an excellent electrical conductor. 24 karat gold is pure. 14 karat gold is 14/24ths pure.

Name: Mercury
Symbol: Hg
Atomic Number: 80
Atomic Mass: 200.59
Atomic Volume: 13.94 cc/mol
Discovered By: Prehistoric
Discovery Date: Mercury has been known since ancient times, liquid mercury has been found in Egyptian tombs from 1500 BC
Origin of Name: Mercury - named after the planet Mercury, the symbol Hg is from (Latin) hydragyrum (liquid silver)
Toxicity: Toxic, particularly vapor; attacks the central nervous system, primarily the cerebral cortex.
Summary: Mercury occurs free in nature only rarely; usually it is found as the ore, cinnabar (HgS). Mercury is sometimes called quicksilver. Mercury is the only common metal that is liquid at room temperature. Mercury has a rather high vapor pressure, and breathing mercury vapor is the cause of mercury poisoning. Used in thermometers and barometers, mercury tooth fillings, and fluorescent lamps.

Name: Thallium
Symbol: Tl
Atomic Number: 81
Atomic Mass: 204.37
Atomic Volume: 17.22 cc/mol
Discovered By: Crookes
Discovery Date: 1861-2
Origin of Name: Thallium - (Greek) thallos, (green shoot or twig, (from its green spectral line))
Toxicity: Apparently toxic. Compounds are toxic; they are strong nerve and protoplasmic poisons; their action is similar to that of arsenic and lead compounds; thallium salts produce trichorrhea.
Summary: Not found free in Nature. Thallium is readily oxidized by air forming a gray coating of oxide.

Name: Lead
Symbol: Pb
Atomic Number: 82
Atomic Mass: 207.19
Atomic Volume: 18.27 cc/mol
Discovered By: Prehistoric
Discovery Date: Lead has been known since ancient times, it is mentioned in the Old Testament, and lead plates were found in the tomb of Ramses II
Origin of Name: Lead - (Anglo-Saxon) lead, the symbol Pb comes from (Latin) plumbum (lead) (Plumbum is also the root of the word plumbing)
Toxicity: Toxic. All salts are toxic and are protoplasmic poisons.
Summary: Rarely found free in Nature, usually as ores. Tarnishes on exposure to air. Used in lead-acid batteries, ammunition, and in solders. Once used in lead tetraethyl, a gasoline anti-knock compound, and in plumbing pipes. Lead compounds were once used as pigments in lead-based pain

Periodic Table of the Elements