Transition metals

The 59 elements that make up Groups 1B through 8B of the periodic table are called transition metals. They form four series. The elements of the first series begin the transition from metals to nonmetals, the elements of the second and third series continue the transition, and the elements of the fourth finish it. These elements are transitional because of the way their electrons are distributed within the atom.

In Groups 1A through 7A, called “representative” elements, the number of electrons in the outer shell (valence electrons) increases as the atomic number increases. But in the transition metals, Groups IB—8B, the number of electrons in the outer shell does not reflect the increase in atomic number—there are never more than two. Instead, it is the number of electrons in the next-inner shell that increases.

First series: Scandium through zinc

Scandium is a soft, silvery-white metal, used mainly in high-intensity lights.

Scandium was one of the “missing” elements predicted by Dimitri Medeleev. It was discovered in 1879 by the Swedish chemist Lars Nil-son (1840-1899). He named it after Scandia, the Latin name for Scandinavia. Its atomic number is 21, and its atomic mass is 44.9559. Its melting point is 1539° C, and its boiling point, 2832° C.

Titanium is a lightweight, silver-gray metal alloyed with other metals and used in aircraft engines.

Titanium was discovered by William Gregor of England in 1791. It was named after the Titans in Greek mythology by Martin Klaproth of Germany in 1795. Its atomic number is 22, and its atomic mass is 47.88. Its melting point is 1667±10° C, and its boiling point, 3287° C.

Vanadium is a silver-white metal alloyed with iron to make parts for aircraft, cars, and locomotives.

Vanadium was discovered in 1830 by the Swedish chemist Nils Sefstrom (1787-1845). He named it after Vanadis, the Scandinavian goddess of beauty. Its atomic number is 23, and its atomic mass is 50.9415. Its melting point is 1890110° C, and its boiling point, about 3380° C.

Chromium is a soft, glossy, gray metal, alloyed with iron to create stainless steel and also used to plate metal parts when a shiny finish is desired.

Chromium was discovered in 1797 by the French chemist Louis Nicolas Vauquelin (1763-1829). Its name comes from the Greek chromos, meaning color. Many of its compounds are highly colored. Its atomic number is 24, and its atomic mass is 51.996. Its melting point is 1900° C, and its boiling point, 2690° C.

Manganese is a brittle, silver-gray metal, used to make special steels and dry-cell batteries.

Manganese was recognized as an element in 1774 by the Swedish chemist Karl Scheele (1774-1786). It was isolated in the same year bythe Swedish chemist Johan Gahn (1745-1818). Its name is probably a corruption of Magnesia, the name of a region of ancient Greece. Its atomic number is 25, and its atomic mass is 54.938. Its melting point is 124413° C, and its boiling point, 1962° C.

Iron, a silvery-white metal, is the fourth most abundant element in the earth’s crust and by far the most commonly used structural metal, although it was not in wide use until about 1000 b.c.

Iron has been known since 4000 b.c Its chemical symbol, Fe, derives from the Latin name for the element, ferrum. Its atomic number is 26, and its atomic mass is 55.847. Its melting point is 1535° C, and its boiling point, 3000° C

Cobalt is a hard, silvery-white metal, magnetic like iron and nickel. It is alloyed with iron to make high-temperature steel and with aluminum and nickel for use in magnets.

Cobalt was isolated in about 1735 by the Swedish chemist Georg Brandt (1694-1768). However, its blue-colored compounds had been known centuries earlier. Its name derives from the German kobold, meaning goblin. Its atomic number is 27, and its atomic mass is 58.9332. Its melting point is 1495° C, and its boiling point, about 2870° C

Nickel is a malleable, magnetic white metal used in making storage batteries and alloyed with iron to make machine parts.

Nickel was isolated in 1751 from an ore containing nickel and arsenic. It was isolated by the Swedish chemist Axel Cronstedt (1722-1765). The ore he used was once called (in German) kupfernickel, from which the element later derived its name. Its atomic number is 28, and its atomic mass is 58.69. Its melting point is 1555° C, and its boiling point, 2837° C.

Copper, a reddish-orange metal, is the principal nonferrous (not containing iron) metal, and one of the few metals used in pure form, especially in electrical wiring. Only silver is a better conductor of electricity, but silver is usually too expensive for that purpose. The electrical industry uses copper wire for transmitting electricity and in a variety of electrical equipment. The green film, called a patina, that forms on copper after long exposure, preserves the metal against further corrosion. Copper is alloyed with nickel to make coins, with zinc to make brass, and with tin to make bronze.

Copper was first used by late Stone Age people around 8000 b.c Its name and its chemical symbol (Cu) derive from the Latin word for metal, cuprum. It occurs naturally as the free metal in balsaltic lavas and also as copper compounds in many minerals. Its atomic number is 29, and its atomic mass is 63.546. Its melting point is 1083.4° C, and its boiling point, 2567° C

Zinc is a shiny, bluish-white metal, hard and brittle at room temperature. It is the fourth most common metal in industry, after iron, copper, and aluminum. Large amounts of zinc are used in alloys. It is combined with aluminum, copper, and magnesium to make die castings; with copper to make brass; and with copper and tin to make bronze. Zinc compounds are used in paint pigments, cosmetics, soaps, and plastics.

The transition metals comprise 59 elements that occupy the central block of the periodic table—from Group IB to Group 8B. They have many common features, based on their electronic structure. As their atomic numbers increase, they add electrons not to their outer shell but to the shell Just inside it. Most are hard, strong metals that melt and boil at high temperatures.

Second series: Yttrium through cadmium

Yttrium is a heavy, silvery-white metal that resembles the elements of the group called the lanthanides. It is used in electronics, especially lasers, and in ceramics, chemicals, and glass.

Yttrium is one of several elements named after the town of Ytterby in Sweden. It was discovered by the Swedish chemist Carl Gustav Mosander (1797-1858) in 1843 in the mineral yttria. Its atomic number is 39, and its atomic mass is 88.9059. Its melting point is 1522±8° C, and its boiling point, 3338° C.

Zirconium is a gray-white metal used in the reactors of nuclear power plants because ft resists corrosion and does not readily absorb the neutrons produced by nuclear fission.

Zirconium was identified in 1789 by the German chemist Martin Klaproth (1743-1817). It was not isolated until 1824, by the Swedish chemist Jons Berzelius (1779-1848). Its name derives from that of its main source, the semiprecious mineral zircon. Its atomic number is 39, and its atomic mass is 91.224. Its melting point is 1857° C, and its boiling point, 4200° C

Niobium, a soft metal varying in color from silvery-white to gray, is used in making high-strength steel for a variety of applications.

Niobium was first discovered in 1801 by the British chemist Charles Hatchett (1765-1847). He named it columbium, a name still used occasionally with the chemical symbol Cb. The element was rediscovered in 1844 by the German chemist Heinrich Rose (1795-1864). He distinguished it from tantalum and named it niobium, after Niobe, the daughter of Tantalus in Greek mythology. Its atomic number is 41, and its atomic mass is 92.9064. Its melting point is 2468110° C, and its boiling point, 4742° C

Molybdenum, a hard silvery-white metal, is combined with other metals to increase their strength, toughness, and resistance to heat and chemicals.

Molybdenum was identified in 1778 by the Swedish chemist Karl Scheele (1744-1786). It was isolated in 1782 by another Swedish chemist, Peter Hjelm. Its name derives from the Greek molybdos, meaning lead, because it was once thought to be a lead ore. Its atomic number is 42, and its atomic mass is 95.94. Its melting point is 2617° C, and its boiling point is about 4612° C.

Two micrographs show silver halide crystals magnified about 3,750 times. To the near right is conventional photographic film and to the far right a new ultrasensitive film. The new film is more sensitive because the flat, regular shape of its large silver halide crystals enables them to absorb more light than the irregular, boulderlike crystals of the other film.

Technetium is a rare, costly silvery-white metal with radioactive isotopes.

Technetium was the first element to be produced artificially. Its name comes from the Greek technetos, meaning artificial. It was discovered in 1937 by the Italian scientists Carlo Perrier and Emilio Segre. Its atomic number is 43, and the atomic mass of its longest-lived isotope is 98. Its melting point is about 2200°C, and its boiling point, about 4850° C.

Ruthenium, a hard, brittle metal, is sometimes alloyed with platinum and palladium to make them harder.

Ruthenium was isolated in 1844 by the Russian chemist Karl Klaus (1796-1864). Its name comes from the medieval Latin Ruthenia for a region in central Europe now part of Ukraine. Its atomic number is 44, and its atomic mass is 101.07. Its melting point is about 2250° C, and its boiling point, about 3900° C.

Rhodium, a silvery-white metal that resists corrosion and can be polished to a high gloss, is used as a finish for mirrors, searchlight reflectors, and jewelry.

Rhodium was isolated in 1803 by the British chemist William Wollaston (1766-1828). He derived its name from the Greek rhodon, meaning rose, because of the red color of many of the element’s compounds in solution. Its atomic number is 45, and its atomic mass is 102.906. Its melting point is 1966±3°C, and its boiling point, 37271100° C.

Palladium is a soft, shiny, silvery-white metal used in jewelry and, combined with platinum, in catalytic converters for automobile engines.

Palladium was isolated in 1803 by William Wollaston. It was named after Pallas, a recently discovered asteroid. Its atomic number is 46, and its atomic mass is 106.42. Its melting point is 1552° C, and its boiling point, 2940° C.

Silver, a soft white metal, is usually combined with another metal to give it strength and hardness. Silver is the best conductor of heat and electricity, and it is used whenever the need for superior electrical conductivity outweighs the metal’s high cost. Various silver compounds have practical applications: the nitrate is used in making silverware and mirrors; the oxide in small powerful batteries for hearing aids, watches, cameras, and calculators; and the bromide in photographic film.

Silver ornaments dating from around 4000 B.c. have been found in royal tombs. Its chemical symbol, Ag, is derived from the Latin word for the metal, argentum. It occurs naturally in the free metallic state and as compounds in various minerals. Its atomic number is 47, and its atomic mass is 107.868. Its melting point is 961° C, and its boiling point, 2193° C.

Cadmium, a soft white metal, is used mainly to plate metals and as an alloying ingredient.

In copper used in electrical equipment, cadmium lends greater strength ana malleability. Its compounds are used in rechargeable batteries, pigments, and coatings for TV screens, photoelectric cells, and solar batteries. Cadmium is highly toxic, and its use is strictly controlled to minimize chances of environmental pollution.

Cadmium was discovered in 1817 by the German chemist Friedrich Stromeyer (1776-1835). He found it as an impurity in a type of zinc carbonate called cadmia, from which the element derives its name. Its atomic number is 48, and its atomic mass is 112.41. Its melting point is 320.9° C, and its boiling point, 765° C.

The lanthanide contraction refers to the steady decrease in the size of the lanthanide ions along the series from lanthanum to lutetium (rather than the expected increase).

Third series I: Lanthanum and the rare earths

Lanthanum, a soft, pliable silvery-white metal, is used in making lighter flints and as a catalyst in the glass industry.

Lathanum was discovered in 1839 as an impurity in cerium by Carl Mosander. Its name derives from the Greek lanthano, which means to be hidden. Its atomic number is 57, and its atomic mass is 138.906. Its melting point is about 920° C, and its boiling point, about 3469° C.

The rare earth elements, also known as the lanthanides, are listed in the accompanying table, along with basic data such as their atomic number and who discovered them.

Third series II: Hafnium through mercury

Hafnium, a silver-colored metal, absorbs neutrons so efficiently that it is used to control the rate of fission reaction in nuclear power plants.

Hafnium was discovered in 1923 by theDutch physicist Dirk Coster (1889-1950) and the Hungarian chemist Georg von Hevesy (1885-1966). Hafnium is derived from Hafnia, the Latin name for Copenhagen (Denmark), where the element was discovered. Its atomic number is 72, and its atomic mass is 178.49. Its melting point is 2227° C, and its boiling point, 4602° C.

Tantalum, a rare silver-colored metal, is so impervious to corrosion that it is used for surgical implants in repairing bone and tissue.

Tantalum was discovered in 1802 by the Swedish chemist Anders Ekeberg (1767-1813).

He named it after Tantalus in Greek mythology because its isolation had proved to be such a tantalizing task. Its atomic number is 73, and its atomic mass is 180.948. Its melting point is 2996° C, and its boiling point is 54251100° C.

Tungsten, a hard silvery-white metal, has the highest melting point of all metals, which makes it useful in equipment that operates at high temperatures, such as the filaments of electronic vacuum tubes and the tips of highspeed cutting tools.

Tungsten derives its name from the Swedish words tung, meaning heavy, and sten, meaning stone. It was first isolated in 1783 by the Spanish scientist Fausto de EIhuyar and his brother Juan. They obtained the metal from the mineral wolframite (iron and manganese tungstate). Hence, the element’s alternative name of wolfram and its chemical symbol W. , Its atomic number is 74, and its atomic mass is 183.85. Its melting point is about 3400° C, and its boiling point is about 5600° C.

Rhenium, a rare, costly, silvery-white metal, can withstand high temperatures. Mixed with platinum or tungsten, it is used to make heat-resistant electrical equipment.

Rhenium was predicted to exist by the Russian chemist Dmitri Mendeleev (1834-1907) in 1869. It was not discovered until 1925, by the German chemists Walter Noddack (1896-1960), Ida Tacke (1896-1978), and Otto Berg, who named it after the River Rhine. Its atomic number is 75, and its atomic mass is 186.207. Its melting point is 3180° C, and its boiling point is about 5627° C.

The electrical contacts of microchips (right) and other electronic devices are often plated with gold. Cold is not only a good electrical conductor, but also protects the contacts from corrosion. This improves reliability.

Osmium, a hard, blue-gray metal with a pungent odor, is the densest metal known. It is used to make extremely hard alloys used in penpoints.

Osmium was discovered in 1804 by the British chemist Smithson Tennant (1761-1815). He named it for the unpleasant smell of some of its compounds. The Greek osme means odor. Its atomic number is 76, and its atomic mass is 190.2. Its melting point is 2700° C, and its boiling point is about 5300° C

Iridium, a brittle white metal, is one of the hardest metals and the most resistant to corrosion. It is used mainly to harden the platinum of penpoints, bearings, and crucibles.

Iridium was discovered in 1804 by Smithson Tennant He derived its name from the latin iris, meaning rainbow. Its compounds exhibit a variety of colors. Its atomic number is 77, and its atomic mass is 192.22. Its melting point is 2410° C, and its boiling point, 4130° C.

Platinum, a soft, silvery-white metal, is one of the heaviest substances known. More valuable than gold, it is used in jewelry and in many alloys.

Tungsten carbide (WC) is one of the most important compounds of tungsten because of its extreme hardness. This makes it useful for the cutting edges of machine tools.

Platinum derives its name from the Spanish platina, meaning “little silver,” because of its resemblance to the latter metal. It was originally discovered by the Italian julius Scaliger in 1557. It was reliably reported in South America in 1735 by the Spanish mathematician Antonio de Ulloa. It was then brought to Europe in 1741 by the British metallurgist Charles Wood. Its atomic number is 78, and its atomic mass is 195.08. Its melting point is 1772° C, and its boiling point is about 3827° C.Gold, a soft yellow metal, is used for coins, jewelry, and emblems, and is accepted by all nations as a form of payment for international debts. It is the most malleable and ductile of all metals. Although it is expensive, gold is increasingly used to plate electrical contacts in electronic equipment.

Gold has been known since prehistoric times. Because it does not corrode and mainly occurs naturally in a relatively pure form, it was one of the first metals used by people. Its chemical symbol, Au, comes from the Latin word for the metal, aurum. Its atomic number is 79, and its atomic mass is 196.967. Its melting point is 1064.43° C, and its boiling point, 2807° C

Mercury, a heavy silvery metal also called quicksilver, is the only metal that exists as a liquid at room temperature. It is used in thermometers, barometers, and electrical switches and relays, and alloyed with silver to fill dental cavities. Mercury-vapor lamps produce light rich in ultraviolet rays. Mercury is a toxic element, and small amounts can build up to dangerous levels in body tissue.

Mercury was named after the Roman god Mercury. Its symbol, Hg, is derived from the Latin Hydrargyrum, meaning liquid silver. The element has been known since ancient times. Samples have been found in tombs dating from about 1500 b.c Its atomic number is 80, and its atomic mass is 200.59. Its melting point is -38.87° C, and its boiling point, 356.58° C.

Fourth series: Actinium through lawrencium

The elements from actinium to lawrencium, known as the actinides, form an offshoot of Group 3B of the periodic table. These highly radioactive elements have many physical and chemical properties in common.

Actinium was discovered in 1899 by the French scientist Andre Debierne. Its name is derived from the Greek aktis, meaning a ray of light. Its atomic number is 89, and its atomic mass is 227.028. Its melting point is 817° C, and its boiling point, 2470° C.

The actinides beyond actinium are listed in the accompanying table, along with basic data such as atomic number and who discovered them.

*A number in parentheses indicates the atomic weight of the most stable isotope.
The seal in the photograph is made of platinum, a precious metal used extensively in jewelry and other such ornamental objects. Platinum has a brilliant silver-white appearance and is very malleable. It is resistant to corrosion by acids, being attacked only by caustic alkalis.
The tips of pen nibs are often made of osmium-iridium alloy, a substance that is very hard and has excellent corrosion resistance. Almost all osmium produced is used in alloys because the pure metal is brittle, even at high temperatures.