Chemical Element

Actinium. The metallic chemical element of atomic number 89. Symbol Ac, specific gravity 10.07, melting point 1,924°F (1,051°C), boiling point 5,788°F (3,198°C). All isotopes of this element are radioactive; the half-life of its most stable isotope, actinium-227, is 21.8 years. Its name is from the Greek aktinos, meaning ray.

Antimony. The metallic chemical element of atomic number 51. Symbol Sb, atomic weight 121.8, specific gravity 6.69, melting point 1,167°F (630.63°C), boiling point 2,889°F (1,587°C). One of its main uses is to alloy with lead in automobile batteries; actinium makes the lead harder.

Arsenic. The metallic chemical element of atomic number 33. Symbol As, atomic weight 74.92, specific gravity 5.73 in gray metallic form, melting point 1,503°F (817°C), sublimes (solid turns to gas) at 1,137°F (614°C). Arsenic compounds are poisonous.

Bismuth. The metallic chemical element of atomic number 83. Symbol Bi, atomic weight 208.98, specific gravity 9.75, melting point 520.5°F (271.4°C), boiling point 2,847.2°F (1,564°C). Bismuth oxychloride is used in "pearlized" cosmetics. Bismuth subsalicylate, an insoluble compound, is the major ingredient in Pepto-Bismol. The soluble compounds of bismuth, however, are poisonous.

Boron. The non-metallic chemical element of atomic number 5. Symbol B, atomic weight 10.81, specific gravity (amorphous form) 2.37, melting point 3,767°F (2,075°C), boiling point 7,232°F (4,000°C). Common compounds are borax, Na₂B₄O₇•10H₂O, used as a cleansing agent and water softener, and boric acid, H₃BO₃, a mild antiseptic and an effective cockroach poison.

Cadmium. The metallic chemical element of atomic number 48. Symbol Cd, atomic weight 112.4, specific gravity 8.65, melting point 609.92°F (321.07°C), boiling point 1,413°F (767°C). A soft, highly toxic metal used in silver solder, in many other alloys, and in nickel-cadmium rechargeable batteries. Because it is an effect absorber of moving neutrons, it is used in control rods for nuclear reactors to slow the chain reaction.

Chromium. The metallic chemical element of atomic number 24. Symbol Cr, atomic weight 51.99, specific gravity 7.19, melting point 3,465°F (1,907°C), boiling point 4,840°F (2,671°C). A hard, shiny metal that takes a high polish. Used to electroplate steel for protection against corrosion and as the major ingredient (next to iron) in stainless steel. Alloyed with nickel, it makes Nichrome, a high-electrical-resistance metal that gets red hot when electric current passes through it; toaster and heater coils are made of Nichrome wire. Chromium is named from the Greek chroma, meaning color, because most of its compounds are highly colored. Chromium is responsible for the green color of emeralds.

Cobalt. The metallic chemical element of atomic number 27. Symbol Co, atomic weight 58.93. Cobalt is a grayish, hard, brittle metal closely resembling iron and nickel. These three metals are the only naturally occurring magnetic elements on Earth.

Gallium. The metallic chemical element of atomic number 31. Symbol Ga, atomic weight 69.72, melting point 85.6°F (29.78°C), boiling point 3,999°F (2,204°C). Gallium is frequently used in the electronics industry and in thermometers that measure a wide range of temperatures.

Germanium. The metallic chemical element of atomic number 32. Symbol Ge, atomic weight 72.59. In pure form, germanium is a brittle crystal. It was used to make the world's first transistor and is still used as a semiconductor in electronics devices.

Gold. The metallic chemical element of atomic number 79. Symbol Au, atomic weight 196.966. This most malleable of metals was probably one of the first elements known to humans. It is usually alloyed with harder metals for use in jewelry, coins, or decorative pieces.

Hafnium. The metallic chemical element of atomic number 72. Symbol Hf, atomic weight 178.49, melting point 4,040.6 ±S68°F (2,227 ±20°C), boiling point 8,315.6°F (4,602°C). Hafnium is strong and resistant to corrosion. It also absorbs neutrons well, making it useful in control rods of nuclear reactors.

Indium. The metallic chemical element of atomic number 49. Symbol In, atomic weight 114.82, melting point 313.89°F (156.61°C), boiling point 3,776°F (2,080°C). Indium is a lustrous, silvery metal that bends easily. It is often alloyed with other metals in solid-stateelectronics devices.

Iridium. The metallic chemical element of atomic number 77. Symbol Ir, atomic weight 192.22. Iridium is an extremely dense metal that resists corrosion better than most others. In its pure state, it is often used in aircraft spark plugs.

Manganese. The metallic chemical element of atomic number 25. Symbol Mn, atomic weight 54.93. The biggest use of manganese is in steelmaking, where it is alloyed with iron. This element is required by all plants and animals, so it is sometimes added as manganese oxide to animal feed.

Mercury. The metallic chemical element of atomic number 80. Symbol Hg, atomic weight 200.59, melting point -37.96°F (-38.87°C), boiling point 673.84°F (356.58°C). Mercury is highly poisonous and causes irreversible damage to the nervous and excretory systems. This element was long used in thermometers because it expands and contracts at a nearly constant rate; however, mercury thermometers are being phased out in favor of alcohol-based and electronic thermometers because of mercury's high toxicity.

Molybdenum. The metallic chemical element of atomic number 42. Symbol Mo, atomic weight 95.94, melting point 4,753°F (2,623°C), boiling point 8,382°F (4,639°C). Molybdenum is used to make superalloyed metals designed for high-temperature processes. It is also found as a trace element in plant and animal tissues.

Nickel. The metallic chemical element of atomic number 28. Symbol Ni, atomic weight 58.71. Nickel is often mixed with other metals, such as copper and iron, to increase the alloy's resistance to heat and moisture.

Niobium. The metallic chemical element of atomic number 41. Symbol Nb, atomic weight 92.90, melting point 4,474.4 ±50°F (2,468 ±10°C), boiling point 8,571.2°F (4,744°C). Niobium is used to strengthen alloys used to make lightweight aircraft frames.

Osmium. The metallic chemical element of atomic number 76. Symbol Os, atomic weight 190.2. Osmium is hard and dense, weighing twice as much as lead. The metal is used to make fountain pen tips and electrical devices.

Palladium. The metallic chemical element of atomic number 46. Symbol Pd, atomic weight 106.42. Palladium is soft. It also readily absorbs hydrogen, and is therefore used to purify hydrogen gas.

Phosphorus. The nonmetallic chemical element of atomic number 15. Symbol P, atomic weight 30.97. Phosphorus is required by all plant and animal cells. Most of the phosphorus in human beings is in the bones and teeth. Phosphorus is heavily used in agricultural fertilizers.

Platinum. The metallic chemical element of atomic number 78. Symbol Pt, atomic weight 195.08, melting point 3,215.1°F (1,768.4°C), boiling point 6,920.6 ±212°F (3,827 ±100°C). Platinum withstands high temperatures well and is used in rocket and jet-engine parts. It is also used as a catalyst in chemical reactions.

Polonium. The metallic chemical element of atomic number 84. Symbol Po, atomic weight 209. Polonium is a product of uranium decay and is 100 times as radioactive as uranium.

Rhenium. The metallic chemical element of atomic number 75. Symbol Re, atomic weight 186.207, specific gravity 21.0, melting point 5,766.8°F (3,186°C), boiling point 10,104.8°F (5,596°C). Rhenium is used in chemical and medical instruments, as a catalyst for the chemical and petroleum industries, and in photoflash lamps.

Rhodium. The metallic chemical element of atomic number 45. Symbol Rh, atomic weight 102.91. This element is similar to palladium. Electroplated rhodium, which is hard and highly reflective, is used as a reflective material for optical instruments.

Ruthenium. The metallic chemical element of atomic number 44. Symbol Ru, atomic weight 101.07, specific gravity 12.5, melting point 4,233.2°F (2,334°C), boiling point 7,502°F (4,150°C). This element is alloyed with platinum and palladium to form hard, resistant contacts for electrical equipment that must withstand a great deal of wear.

Scandium. The metallic chemical element of atomic number 21. Symbol Sc, atomic weight 44.96, melting point 2,805.8°F (1,541°C), boiling point 5,127.8°F (2,831°C). Scandium is a silvery-white metal that develops a yellowish or pinkish cast when exposed to air. It has relatively few commercial applications.

Selenium. The nonmetallic chemical element of atomic number 34. Symbol Se, atomic weight 78.96. Selenium is able to convert light directly into electricity, and its resistance to electrical current decreases when it is exposed to light. Both properties make this element useful in photocells, exposure meters, and solar cells.

Silver. The metallic chemical element of atomic number 47. Symbol Ag, atomic weight 107.87. Silver has long been used in the manufacture of coins. It is also an excellent conductor of heat and electricity. Some compounds of silver are light-sensitive, making silver important in the manufacture of photographic films and papers.

Tantalum. The metallic chemical element of atomic number 73. Symbol Ta, atomic weight 180.95, melting point 5,462.6°F (3,017°C), boiling point of 9,797 ±212°F (5,425 ±100°C). Tantalum is a heavy, gray, hard metal that is used in alloys to pen points and analytical weights.

Technetium. The metallic chemical element of atomic number 43. Symbol Tc, atomic weight 98. Technetium was the first element to be produced synthetically; scientists have never detected the natural presence of this element on Earth.

Tellurium. The nonmetallic chemical element of atomic number 52. Symbol Te, atomic weight 127.60, melting point 841.1 ±32.54°F (449.5 ±0.3°C), boiling point 1,813.64 ±38.84°F (989.8 ±3.8°C). Tellurium is a grayish-white, lustrous, brittle metal. It is a semiconductor and is used in the electronics industry.

Thallium. The metallic chemical element of atomic number 81. Symbol Tl, atomic weight 204.38. Thallium is a bluish-gray metal that is soft enough to be cut with a knife. Thallium sulfate is used as a rodenticide and ant poison.

Tin. The metallic chemical element of atomic number 50. Symbol Sn, atomic weight 118.69. Tin is alloyed with copper and antimony to make pewter. It is also used as a soft solder and as coating to prevent other metals from corrosion.

Titanium. The metallic chemical element of atomic number 22. Symbol Ti, atomic weight 47.90, melting point 3,020 ±50°F (1,660 ±10°C), boiling point 5,948.6°F (3,287°C). This element occurs as a bright, lustrous brittle metal or dark gray powder. Titanium alloys are strong for their weight and can withstand large changes in temperature.

Tungsten. The metallic chemical element of atomic number 74. Symbol W, atomic weight 183.85, melting point 6,170 ±68°F (3,410 ±20°C). The melting point of tungsten is higher than that of any other metal. Its chief use is as a filament in electric light bulbs.

Vanadium. The metallic chemical element of atomic number 23. Symbol V, atomic weight 50.94. Pure vanadium is bright white. This metal finds its biggest use in strengthening steel.

Yttrium. The metallic chemical element of atomic number 39. Symbol Y, atomic weight 88.91, melting point 2,771.6 ±46.4°F (1,522 ±8°C), boiling point 6,040.4°F (3,338°C). Yttrium is a relatively active metal that decomposes in cold water slowly and in boiling water rapidly. Certain compounds containing yttrium have been shown to become superconducting at relatively high temperatures.

Zinc. The metallic chemical element of atomic number 30. Symbol Zn, atomic weight 65.39. Zinc, a brittle metal at room temperature, forms highly versatile alloys in industry. One zinc alloy is nearly as strong as steel, but has the malleability of plastic.

Zirconium. The metallic chemical element of atomic number 40. Symbol Zr, atomic weight 91.22, melting point 3,365.6 ±35.6°F (1,852 ±2°C), boiling point 7,910.6°F (4,377°C). Neutrons can pass through this metal without being absorbed; this makes it highly desirable as a construction material for the metal rods containing the fuel pellets in nuclear power plants.