Britannica Concise 2005

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zos; most of the rest are Indians. Lan¬ guage: Spanish (official). Religion: Christianity (predominantly Roman Catholic; also Protestant, other Christians). Currency: U.S. dollar. The smallest and

most densely populated Central American country, it is crossed by two volcanic mountain ranges and has a narrow coastal region and a high cen¬ tral plain in the south. The climate ranges from hot and wet in the low¬ lands to cooler and wetter in the highlands. Cloud forests predominate at the highest elevations. El Salvador has a developing economy based on trade, manufacturing, and agriculture, with coffee, sugarcane, and cotton the major export crops. It is a republic with one legislative house; its chief of state and government is the president. The Spanish arrived in the area in 1524 and subjugated the Pipil Indian kingdom of Cuzcatlan by 1539. The country was divided into two districts, San Salvador and Sonsonate, both attached to Guatemala. When Spanish rule ended in 1821, the Sal¬ vadorans opposed incorporation into the Mexican Empire (confronting both Guatemalan and Mexican armies), and, upon its collapse in 1823, Sonsonate and San Salvador combined to form the new state of El Sal¬ vador within the United Provinces of Central America. The country attained independence in 1841. From its founding, it experienced a high degree of political turmoil; powerful economic interests controlled the country through most of the 19th and early 20th centuries but were replaced by a military dictatorship that lasted from 1931 to 1979. Elec¬ tions held in 1982 set up a new government, and, though a new consti¬ tution was adopted in 1983, civil war continued throughout the 1980s. An accord in 1992 brought peace, but violent crime became a major prob¬ lem. Despite attempts at economic reform, the country was plagued by inflation and unemployment into the 21st century.

Elagabalus \,e-b-'ga-b3-bs\ or Heliogabalus \,he-le-o-'ga-b3-bs\ officially Caesar Marcus Aurelius Antoninus Augustus orig. Varius Avitus Bassianus (b. 204, Emesa, Syria—d. 222) Roman emperor (218-22) notable for his eccentric behaviour. Passed off as Car- acalla’s illegitimate son, he became emperor with the support of the army. He identified himself with the Syrian god Baal and imposed Baal worship on the empire. His execution of dissidents, promotion of favourites, and homosexual orgies outraged the Romans. After he named his cousin Alex¬ ander heir and then changed his mind, the Praetorian Guards mutinied, murdered him, and made Alexander emperor.

Elam Ve-bm\ Ancient country of the Middle East. It was located in what is now southwestern Iran, at the head of the Persian Gulf and east of

ancient Babylonia; its capital was Susa (the country, thus, is sometimes known as Susiana). It had close cultural ties to Mesopotamia and was in conflict with the Sumerians (see Sumer) and Akkadians (see Akkad) from c. 3000 bc. In the 13th century bc, it became a dominant power that included most of Mesopotamia east of the Tigris and reached almost to Persepolis. Its domination ended when Nebuchadrezzar I of Babylon (r. 1124-1103 bc) captured Susa. Later, Elam formed a satrapy of the Per¬ sian Achaemenian dynasty, and Susa became one of its capitals.

eland \'e-bnd\ Either of two species of easily tamed, oxlike antelope (genus Taurotragus) found in herds on the plains or in lightly wooded areas of central and southern Africa.

The largest of the antelope, they may stand up to 6 ft (1.8 m) tall at the shoulder and weigh as much as 2,200 lbs (1,000 kg). They have a short, dark mane, a dewlap hanging from the throat, and long horns twisted in a tight spiral. The common eland is pale brown, becoming blue-gray with age, and often marked with nar¬ row, vertical white stripes. The giant, or Derby, eland is reddish brown with a blackish neck and vertical white stripes and horns heavier than those of the common eland.

elapid Ve-b-pod\ Any of about 200 species of venomous snakes (fam¬ ily Elapidae) that have short fangs fixed in the front of the upper jaw. Elapids are found in the New World, Africa, southern Asia, Pacific Islands, and Australia. Slender and agile, most are small and harmless to humans, but they include the largest and most lethal of snakes. Their venom is primarily neurotoxic but often contains substances that damage body tis¬ sues or blood cells. The relatively painless bite may cause a swift death from paralysis of the heart and lungs. See also black snake, cobra, coral SNAKE, MAMBA.

elastic modulus or elastic constant In materials science and physi¬ cal metallurgy, any of various numbers that quantify the response of a material to elastic or springy deflection. When tensile stress is applied to a material, the resulting strain is determined by Young’s modulus (see Thomas Young), a constant defined as the ratio of the stress in a body to the corresponding strain. It has dimensions of (force)/(length) 2 and is measured in units such as the pascal or newton per square meter (1 Pa = 1 N/m 2 ), dyne/cm 2 , or lbs per sq in. (psi). See also elasticity.

elasticity Ability of a deformed material body to return to its original shape and size when the forces causing deformation are removed. Most solids show some elastic behaviour, but there is usually a limit—the mate¬ rial’s “elastic limit”—to the force from which recovery is possible. Stresses beyond its elastic limit cause the material to yield, or flow, and the result is permanent deformation or breakage. The limit depends on the material’s internal structure; for example, steel, though strong, has a low elastic limit and can be extended only about 1% of its length, whereas rubber can be elastically extended up to about 1,000%. Robert Hooke, one of the first to study elasticity, developed a mathematical relation between tension and extension.

Elba Island off the western coast of Italy, in the Tyrrhenian Sea. Occupy¬ ing an area of 86 sq mi (223 sq km), it is the largest island of the Tuscan Archipelago. France obtained Elba from Rome in 1802. When Napoleon abdicated in May 1814, he was exiled to Elba. The island was recognized as an independent principality with Napoleon as its ruler until February 1815, when he returned to France to begin the Hundred Days. Thereafter Elba was restored to Tuscany.

Elbe Vel-boN River Czech Labe Vla-be\ ancient Albis River, central Europe. One of the continent’s major waterways, it rises in the Krkonose (Giant) Mountains on the border of the Czech Republic and Poland and flows southwest across Bohemia. It then flows northwest across Germany and empties into the North Sea near Cuxhaven. From 1945 to 1990 it formed part of the boundary between East and West Germany. It is 724 mi ( 1 , 1 65 km) long and connected by canals with the Baltic Sea, the Havel River and Berlin, the Ruhr industrial region, and the Rhine River. It is navi¬ gable for 1,000-ton barges as far upstream as Prague through the Vltava River. Hamburg, Ger., is 55 mi (88 km) upstream from its mouth.

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Giant eland (Taurotragus derbianus)

LEONARD LEE RUE III

© 2006 Encyclopaedia Britannica, Inc.

606 i Elbrus ► electoral system

Elbrus \el-'briis. Mount Peak, Caucasus Mountains, southwestern Rus¬ sia. The highest peak in the Caucasus, it is an extinct volcano with twin cones reaching elevations of 18,510 ft (5,642 m) and 18,356 ft (5,595 m). There are many mineral springs along its descending streams, while 53 sq mi (138 sq km) of Elbrus is covered by 22 glaciers. It is a major cen¬ tre for mountaineering and tourism.

Elburz \el-'burz\ Mountains Mountain range, northern Iran. It is 560 mi (900 km) long and extends along the southern shore of the Caspian Sea, from which it is separated by a narrow coastal lowland. It includes Iran’s highest peak, Mount Damavand (Demavend), at 18,605 ft (5,671 m). The forests of the Elburz cover some 12,500 sq mi (32,400 sq km). The Hyrcanian tigers for which they were famous are now rare, but other wild cats, including the leopard and the lynx, are still numerous.

elder Any of about 20-30 species, mainly shrubs and small trees, that make up the genus Sambucus, in the honeysuckle family. Most are native to forested temperate or subtropical areas. Elders are important as garden shrubs, as forest plants, and for their berries (elderberries), which provide food for wildlife and are used for wines, jellies, pies, and folk medi¬ cines. Elders have divided leaves and flat, roundish clusters of tiny, yellowish-white, saucer-shaped flowers. The American, or sweet, elder (5. canadensis) of North America is the most important spe¬ cies horticulturally.

elder, box See box elder

Elder, John (b. March 8, 1824,

Glasgow, Scot.—d. Sept. 17, 1869,

London, Eng.) Scottish marine engi¬ neer. In 1854 he developed the marine compound steam engine (using both high- and low-pressure steam), which enabled seagoing vessels to save 30-40% of the coal they had been burning and helped make practical long voyages on which refueling was impossible.

Eldridge, (David) Roy (b. Jan. 30, 1911, Pittsburgh, Pa., U.S.—d. Feb. 26, 1989, Valley Stream, N.Y.) U.S. trumpeter, one of the most vital and creative jazz musicians of the swing era. He was influenced by saxo¬ phonists such as Coleman Hawkins and developed a fast, nimble technique matched with harmonic sophistication. He played with Fletcher Henderson (1935-36) and was featured with the big bands of Gene Krupa and Artie Shaw in the 1940s. (A nickname reflecting his stature, “Little Jazz,” was also the title of a record he made with Shaw). The dominant voice on his instrument in the swing style, he exerted a strong influence on bebop musi¬ cians.

Eleanor of Aquitaine (b. c. 1122—d. April 1, 1204, Fontevrault, Anjou, Fr.) Queen consort of Louis VII of France (1137-80) and Henry II of England (1152-89), the most powerful woman of 12th-century Europe. She inherited the duchy of Aquitaine and married the heir to the French throne. Beautiful, capricious, and strong-willed, she accompanied Louis on the Second Crusade (1147-49), and her conduct aroused his jealousy. The marriage was annulled (1152), and she married Henry Plantagenet, soon to be Henry II; the marriage united England, Normandy, and west¬ ern France under his rule. She bore Henry five sons, including the future kings Richard I the Lionheart and John Lackland, and three daughters who married into other royal houses. Her court at Poitiers became a centre of culture, fostering the poetry of the troubadours. She may have spurred her sons to revolt against Henry (1173); when the rebellion failed she was captured and confined until his death (1189). She was active in govern¬ ment during the reign of Richard I, ruling during his crusade to the Holy Land and ransoming him from Austria. After Richard died (1199) and John became king, she saved Anjou and Aquitaine for John against French threats, then retired to the monastery at Fontevrault.

Eleanor of Castile (b. 1246—d. Nov. 28, 1290, Harby, Nottingham¬ shire, Eng.) Queen consort of Edward I of England. Daughter of the king of Castile, she brought Edward title to Gascony on their marriage in 1254, and she was sent to France for safety during the baronial rebellion (1264-

65). She joined Edward on a crusade to the Holy Land (1270-73), and legend says she saved his life by sucking poison from a dagger wound. On her death, Edward erected Eleanor Crosses at each place where her coffin rested en route to London.

Eleaticism V.el-e-'a-to-.si-zomX School of pre-Socratic philosophy that flourished in the 5th century bc. It took its name from the Greek colony of Elea (Velia) in southern Italy. It is distinguished by its radical MONISM— i.e., its doctrine of the One, according to which all that exists is a static plenum of Being as such, and nothing exists that stands either in contrast or in contradiction to Being. Thus, all differentiation, motion, and change must be illusory. Its literary sources consist of fragments (most less than 10 lines long) preserved by later Classical authors: 19 from Parmenides, 4 from his pupil Zeno of Elea, and 10 from another pupil, Melissus (fl. 5th century bc). See also pre-Socratics.

Eleazar \,el-e- l a-zor\ ben Judah of Worms orig. Eleazar ben Judah ben Kalonymos (b. 1160, Mainz, Franconia—d. 1238, Worms) German Jewish mystic and Talmudic scholar. His wife and daughters were killed by Crusaders in 1196, but he nevertheless contin¬ ued to teach a doctrine of love of humanity. After studying with Judah ben Samuel, to whom he was related, he became a rabbi at Worms (1201). Eleazar attempted to unify the mysticism of the Kabbala with the Talmud. His greatest work was his ethical code, Rokeah (1505). He believed that God himself was unknowable but that the kavod, a ruling angel that was an emanation from God, was knowable. His writings are a major source of information on medieval Hasidism.

election Formal process by which voters make their political choices on public issues or candidates for public office. The use of elections in the modern era dates to the emergence of representative government in Europe and North America since the 17th century. Regular elections serve to hold leaders accountable for their performance and permit an exchange of influence between the governors and the governed. The availability of alternatives is a necessary condition. Votes may be secret or public. See also ELECTORAL SYSTEM, PARTY SYSTEM, PLEBISCITE, PRIMARY ELECTION, REFERENDUM AND INITIATIVE.

elector German Kurfurst. Prince of the Holy Roman Empire who had a right to participate in electing the German emperor. Beginning c. 1273, and with the confirmation of the Golden Bull, there were seven electors: the archbishops of Trier, Mainz, and Cologne; the duke of Saxony; the count palatine of the Rhine; the margrave of Brandenburg; and the king of Bohemia. Other electorates were created much later for Bavaria (1623— 1778), Hanover (1708), and Hesse-Kassel (1803), but by the 17th century the electors’ office had become meaningless because the Habsburg dynasty produced the de facto emperors. The office disappeared when the empire was abolished in 1806.

electoral college Constitutionally mandated process for electing the U.S. president and vice president. Each state appoints as many electors as it has senators and representatives in Congress (U.S. senators, represen¬ tatives, and government officers are ineligible); the District of Columbia has three votes. A winner-take-all rule operates in every state except Maine and Nebraska. Three presidents have been elected by means of an electoral college victory while losing the national popular vote (Ruther¬ ford B. Hayes in 1877, Benjamin Harrison in 1888, and George W. Bush in 2000). Though pledged to vote for their state’s winners, electors are not constitutionally obliged to do so. A candidate must win 270 of the 538 votes to win the election.

Electoral Commission (1877) Commission created to resolve the disputed 1876 presidential election between Republican Rutherford B. Hayes and Democrat Samuel Tilden. Tilden had won the popular vote and was only one electoral vote short of victory, but the Republicans contested the tallies in four states, charging fraud. Unable to reach a consensus, Congress appointed a 15-member commission, evenly divided between the two parties, except for one justice, Joseph R Bradley, a Republican considered nonpartisan; Republicans pressured him, and the tally went to Hayes, who was declared the winner on March 2. See also Wormley Con¬ ference.

electoral system Method and rules of counting votes to determine the outcome of elections. Winners may be determined by a plurality, a major¬ ity (more than 50% of the vote), an extraordinary majority (a percentage of the vote greater than 50%), or unanimity. Candidates for public office may be elected directly or indirectly. Proportional representation is used

European red elder (Sambucus race- mosa).

AJ. HUXLEY

© 2006 Encyclopaedia Britannica, Inc.

Electro ► electric shock I 607

in some areas to ensure a fairer distribution of legislative seats to con¬ stituencies that may be denied representation under the plurality or major¬ ity formulas. See also party system, plurality system, primary election.

Electra In Greek legend, the daughter of Agamemnon and Clytemnestra. When Agamemnon was murdered by Clytemnestra and her lover Aegis- thus, Electra saved her young brother Orestes from the same fate by send¬ ing him away. Orestes later returned, and Electra helped him kill their mother and Aegisthus. She then married her brother’s friend Pylades. The story is treated in plays by Aeschylus, Sophocles, and Euripides.

Electra complex See Oedipus complex

electric automobile Battery-powered motor vehicle. Originating in the 1880s, electric cars were used for private passenger, truck, and bus transportation in cities, where their low speeds and limited battery range were not drawbacks, and the cars became popular for their quietness and low maintenance costs. Until 1920 they were competitive with gasoline- fueled cars; they became less so after the electric self-starter made gasoline-powered cars more attractive and mass production made them cheaper to produce. In Europe electric vehicles have been used as short- range delivery vans. Renewed interest in electric cars beginning in the 1970s, spurred especially by new consciousness of foreign oil dependency and environmental concern, led to improvements in speed and range. Recent laws, particularly in California, have mandated commercial pro¬ duction. “Hybrid” cars employing both electric and internal combustion engines and providing the best features of both technologies, have recently become commercially available. Experimental vehicles have used solar FUEL CELLS.

electric charge Quantity of electricity that flows in electric currents or that accumulates on the surfaces of dissimilar nonmetallic substances that are rubbed together briskly. It occurs in discrete natural units, equal to the charge of an electron or proton. It cannot be created or destroyed. Charge can be positive or negative; one positive charge can combine with one negative charge, and the result is a net charge of zero. Two objects that have an excess of the same type of charge repel each other, while two objects with an excess of opposite charge attract each other. The unit of charge is the coulomb, which consists of 6.24 x 10 18 natural units of elec¬ tric charge.

electric circuit See circuit

electric current Movement of electric charge carriers. In a wire, elec¬ tric current is a flow of electrons that have been dislodged from atoms and is a measure of the quantity of electrical charge passing any point of the wire per unit time. Current in gases and liquids generally consists of a flow of positive ions in one direction together with a flow of negative ions in the opposite direction. Conventionally, the direction of electric current is that of the flow of the positive ions. In alternating current (AC) the motion of the charges is periodically reversed; in direct current (DC) it is not. A common unit of current is the ampere, a flow of one coulomb of charge per second, or 6.24 x 10 18 electrons per second.

electric dipole VdI-pol\ Pair of equal and opposite electric charges, the centres of which do not coincide. An atom in which the centre of the negative cloud of electrons has been shifted slightly away from the nucleus by an external electric field is an induced electric dipole. When the exter¬ nal field is removed, the atom loses its dipolarity. A water molecule, in which two hydrogen atoms are situated to one side of an oxygen atom, is a permanent electric dipole. The oxygen side is always slightly negative, the hydrogen side slightly positive.

electric discharge lamp o/ vapor lamp Lighting device consist¬ ing of a transparent container within which a gas is energized by an applied voltage and made to glow. After practical generators were devised in the 19th century, many experimenters applied electric power to tubes of gas. From c. 1900, electric discharge lamps were in use in Europe and the U.S. Fluorescent, neon, mercury, sodium, and metal-halide lamps are of the electric discharge variety.

electric eel Eel-shaped South American fish (Electrophones electricus ) capable of producing an electric shock strong enough to stun a human. The electric eel (not a true eel) is a sluggish inhabitant of slow freshwater, sur¬ facing periodically to gulp air. Long, cylindrical, scaleless, and gray- brown, it sometimes reaches a length of 9 ft (2.75 m) and a weight of 49 lbs (22 kg). The tail region, bordered below by a long anal fin that the fish

undulates to move about, contains the electric organs. The shock (up to 650 volts discharged at will) is used mainly to immobilize fish and other prey.

electric eye See photocell

electric field Region around an electric charge in which an electric force is exerted on another charge. The strength of an electric field E at any point is defined as the electric force F exerted per unit positive electric charge q at that point, or E = F/q. An electric field has both magnitude and direction and can be represented by lines of force, or field lines, that start on positive charges and terminate on negative charges. The electric field is stronger where the field lines are close together than where they are farther apart. The value of the electric field has dimensions of force per unit charge and is measured in units of newtons per coulomb.

electric force or Coulomb force Force between two electric charges. The magnitude of the force F is proportional to the product of the two charges, q 1 and q 2 , divided by the square of the distance r between them, or F = kq^q-Jr 1 , where k is a constant that depends on the measurement system being used. The electric force can be one of repulsion, such as the force between two objects having like charges, or it can be attractive, such as the force between two objects having opposite charges.

electric furnace Chamber heated with electricity to very high tem¬ peratures, for melting and alloying metals and refractories. Modern elec¬ tric furnaces generally are either arc furnaces or induction furnaces. Arc furnaces produce roughly two-fifths of the steel made in the U.S. In the induction furnace, a coil carrying alternating electric current surrounds the container or chamber of metal; circulating eddy currents induced in the metal produce extremely high temperatures.

electric potential Amount of work needed to move a unit electric charge from a reference point to a specific point against an electric field. The potential energy of a positive charge increases when it moves against an electric field, and decreases when it moves with the field. Electric potential can be thought of as potential energy per unit charge. The work done in moving a unit charge from one point to another, as in an electric circuit, is equal to the difference in potential energies at each point. Elec¬ tric potential is expressed in units of joules per coulomb, or volts.

electric ray Any of the aquatic rays (families Torpedinidae, Narkidae, and Temeridae) that produce an electrical shock. They are found world¬ wide in warm and temperate seas, mostly in shallow water but some (genus Benthobatis) at depths greater than 3,000 ft (900 m). Slow-moving bottom-dwellers, they feed on fishes and invertebrates. They range in length from less than 1 ft (30 cm) to about 6 ft (1.8 m) and have a short, stout tail. They are soft and smooth-skinned, with a circular or nearly cir¬ cular body disk formed by the head and pectoral fins. They are harmless unless touched or stepped on. The electric organs, composed of modified muscle tissue, are in the disk near the head. The shock from these organs, which may reach 220 volts and is strong enough to fell a human adult, is used for defense, sensory location, and capturing prey.

Electric ray (Narcine brasiliensis)

DOUGLAS FAULKNER

electric shock Physical effect of an electric current that enters the body, ranging from a minor static-electricity discharge to a power-line accident or lightning strike but most often resulting from house current. The effects

© 2006 Encyclopaedia Britannica, Inc.

608 I electrical engineering ► electromagnetic field

depend on the current (not the voltage), and the worst damage occurs along its path from the entry to the exit point. Causes of immediate death are ventricular fibrillation and paralysis of the brain’s breathing centre or of the heart. Cardiopulmonary resuscitation is the best first aid. Though most survivors recover completely, aftereffects may include cataract, angina pectoris, or nervous-system disorders.

electrical engineering Branch of engineering concerned with the practical applications of electricity in all its forms, including those of elec¬ tronics. Electrical engineering deals with electric light and power systems and apparatuses; electronics engineering deals with wire and radio com¬ munication, the stored-program electronic computer, radar, and automatic control systems. The first practical application of electricity was the tele¬ graph, in 1837. Electrical engineering emerged as a discipline in 1864 when James Clerk Maxwell summarized the basic laws of electricity in mathematical form and predicted that radiation of electromagnetic energy would occur in a form that later became known as radio waves. The need for electrical engineers was not felt until the invention of the telephone (1876) and the incandescent lamp (1878).

electrical impedance \im-'pe-d 3 ns\ Opposition that a circuit presents to electric current. It includes both resistance and reactance. Resistance arises from collisions of the current-carrying charged particles with the internal structure of the conductor. Reactance is an additional opposition to the movement of electric charge that arises from the changing electric and magnetic fields in circuits carrying alternating current. Impedance in circuits carrying steady direct currents is simply resistance. The magni¬ tude of the impedance Z of a circuit is equal to the maximum value of the potential difference, or voltage V, across the circuit, divided by the maximum value of the current I through the circuit, or simply Z = VII. The unit of impedance is the ohm.

electricity Phenomenon associated with stationary or moving electric charges. The word comes from the Greek elektron (“amber”); the Greeks discovered that amber rubbed with fur attracted light objects such as feathers. Such effects due to stationary charges, or static electricity, were the first electrical phenomena to be studied. Not until the early 19th cen¬ tury were static electricity and electric current shown to be aspects of the same phenomenon. The discovery of the electron, which carries a charge designated as negative, showed that the various manifestations of elec¬ tricity are the result of the accumulation or motion of numbers of elec¬ trons. The invention of the incandescent lightbulb (1879) and the construction of the first central power station (1881) by Thomas Alva Edi¬ son led to the rapid introduction of electric power into factories and homes. See also James Clerk AAaxwell.

electrification, rural See rural electrification

electrocardiography \i-,lek-tro- l kard-e-'ag-r3-fe\ Method of tracing the electric current of a heartbeat to provide information on the heart. Electrocardiograms (ECGs) are made by applying electrodes, usually to the arms, legs, and chest wall, attached to an electrocardiograph, which records the tiny heart current. Upward and downward movements on the tracing reflect contractions of the atria and ventricles. Deviations from a standard point to a possible heart disorder and its site, as well as to pos¬ sible high blood pressure and other diseases.

electrochemistry Branch of chemistry concerned with the relation between electricity and chemical change. Many spontaneous chemical reac¬ tions liberate electrical energy, and some of these reactions are used in batteries and fuel cells to produce electric power. Conversely, electric cur¬ rent can bring about many reactions that do not occur spontaneously. In the process called electrolysis, electrical energy is converted directly into chemical energy, which is stored in the products of the reaction. This pro¬ cess is applied in refining metals, in electroplating, and in producing hydrogen and oxygen from water. Passage of electricity through a gas generally causes chemical changes, a subject that forms a separate branch of electrochemistry. See also oxidation-reduction.

electroconvulsive therapy formerly shock therapy Method of treating psychiatric disorders by inducing shock through electric current. Electroconvulsive, or electroshock, therapy involves passing an electric current through the patient’s head between two electrodes placed over the temples and thus causing a convulsive seizure; it was used to treat bipolar disorder and other types of depression. Shock was previously induced by administering increasingly large doses of insulin until the patient was thrown into a brief coma; the so-called insulin-shock therapy was used

for the treatment of schizophrenia. Both forms of shock therapy were devel¬ oped in the 1930s. Their use declined after the introduction of tranquil- izing drugs and antidepressants.

electrocution Method of execution in which the condemned person is subjected to a heavy charge of electric current. The prisoner is shackled into a wired chair, and electrodes are fastened to the head and one leg so that the current will flow through the body. One electrical shock may not be enough to kill the person; if a doctor does not confirm the death, sev¬ eral shocks may be applied. The electric chair was first used in 1890. Electrocution also refers to death by other causes of electrical shock (e.g., accidental contact with high-voltage wiring).

electrode Electric conductor, usually metal, used as one of two termi¬ nals to conduct electric current through a conducting medium. A simple voltaic cell, or battery, consists of two electrodes, usually one zinc and one copper, immersed in an electrolytic solution (see electrolyte). When a chemical reaction occurs in the solution, electrons gather on the zinc elec¬ trode, or cathode, which becomes negatively charged. At the same time, electrons are drawn from the copper electrode, the anode, giving it a posi¬ tive charge. The difference in charge sets up a potential difference, or voltage, between the two electrodes. When they are connected by a con¬ ducting wire, electrons flow from the cathode to the anode, producing a current.

electrodynamics, quantum See quantum electrodynamics

electroencephalography U-.lek-tro-in-.sef-o-Tag-ro-feV Technique for recording electrical activity in the brain, whose cells emit distinct pat¬ terns of rhythmic electrical impulses. Pairs of electrodes on the scalp transmit signals to an electroencephalograph, which records them as peaks and troughs on a tracing called an electroencephalogram (EEG). Differ¬ ent wave patterns on the EEG are associated with normal and abnormal waking and sleeping states. They help diagnose conditions such as tumours, infections, and epilepsy. The electroencephalograph was invented in the 1920s by Hans Berger (1873-1941).

electrolysis \i-,lek-'tra-l9-s3s\ Process in which electric current passed through a substance causes a chemical change, usually the gaining or losing of electrons (see oxidation-reduction). It is carried out in an electrolytic cell consisting of separated positive and negative electrodes (anode and cath¬ ode, respectively) immersed in an electrolyte solution containing ions or in a molten ionic compound. Electric current enters through the cathode; posi¬ tively charged cations travel to it and combine with electrons. Negatively charged anions give up electrons at the anode. Both thus become neutral molecules. Electrolysis is used extensively in metallurgy to extract or purify metals from ores or compounds and to deposit them from solution (electro¬ plating). Electrolysis of molten sodium chloride yields metallic sodium and chlorine gas; that of a strong solution of sodium chloride in water (brine) yields hydrogen gas, chlorine gas, and sodium hydroxide (in solution); and that of water (with a low concentration of dissolved sodium chloride or other electrolyte) yields hydrogen and oxygen.

electrolyte Substance that conducts electric current as a result of disso¬ ciation of its molecules into positively and negatively charged particles called ions. The most familiar electrolytes are acids, bases, and salts, which ionize when dissolved in polar solvents such as water. Many salts, includ¬ ing sodium chloride, behave as electrolytes when melted in the absence of solvent, since they have ionic bonds. The most commonly used electro¬ lytes are dissolved metal salts (for electroplating metals) and acids (in electric batteries). See also electrolysis.

electromagnet Device consisting of a core of magnetic material such as iron, surrounded by a coil through which an electric current is passed to magnetize the core. When the current is stopped, the core is no longer mag¬ netized. Electromagnets are particularly useful wherever controllable mag¬ nets are required, as in devices in which the magnetic field is to be varied, reversed, or switched on and off. Suitably designed magnets can lift many times their own weight and are used in steelworks and scrap yards to lift loads of metal. Other devices that utilize electromagnets include particle accelerators, telephone receivers, loudspeakers, and televisions.

electromagnetic field Property of space caused by the motion of an electric charge. A stationary charge produces an electric field in the sur¬ rounding space. If the charge is moving, a magnetic field is also produced. A changing magnetic field also produces an electric field. The interaction of electric and magnetic fields produces an electromagnetic field, which

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electromagnetic force ► electronic music I 609

has its own existence in space apart from the charges involved. An elec¬ tromagnetic field can sometimes be described as a wave that transports ELECTROMAGNETIC RADIATION.

electromagnetic force One of the four known basic forces in the universe. Electromagnetism is responsible for interactions between charged particles that occur because of their charge, and for the emission and absorption of photons (electromagnetic radiation). The phenomena of electricity and magnetism are consequences of this force, and the relation¬ ships between them were first described by James Clerk Maxwell in the 1860s. The physical description of electromagnetism has since been com¬ bined with quantum mechanics into the theory of quantum electrodynamics. The electromagnetic force is about 10 36 times as strong as the gravita¬ tional force (see gravitation), but significantly weaker than both the weak force and the strong force.

electromagnetic induction Induction of an electromotive force in a circuit by varying the magnetic flux linked with the circuit. The phenom¬ enon was first investigated in 1830-31 by Joseph Henry and Michael Fara¬ day, who discovered that when the magnetic field around an electromagnet was increased or decreased, an electric current could be detected in a sepa¬ rate nearby conductor. A current can also be induced by constantly mov¬ ing a permanent magnet in and out of a coil of wire, or by constantly moving a conductor near a stationary permanent magnet. The induced electromotive force is proportional to the rate of change of the magnetic flux cutting across the circuit.

electromagnetic radiation Energy propagated through free space or through a material medium in the form of electromagnetic waves. Examples include radio waves, infrared radiation, visible light, ultraviolet radiation, X rays, and gamma rays. Electromagnetic radiation exhibits wavelike properties such as reflection, refraction, diffraction, and interfer¬ ence, but also exhibits particlelike properties in that its energy occurs in discrete packets, or quanta. Though all types of electromagnetic radiation travel at the same speed, they vary in frequency and wavelength, and inter¬ act with matter differently. A vacuum is the only perfectly transparent medium; all others absorb some frequencies of electromagnetic radiation.

electromagnetic spectrum Total range of frequencies or wavelengths of electromagnetic radiation. The spectrum ranges from waves of long wavelength (low frequency) to those of short wavelength (high fre¬ quency); it comprises, in order of increasing frequency (or decreasing wavelength): very-low-frequency to ultrahigh-frequency radio waves, MICROWAVES, INFRARED RADIATION, visible UGHT, ULTRAVIOLET RADIATION, X-RAYS, and gamma rays. In a vacuum, all waves of the electromagnetic spectrum travel at the same speed: 299,792,458 m/sec (186,282 mi/sec).

red orange yellow green blue violet

microwaves ultraviolet gamma rays

radio, TV waves infrared x-rays

The spectrum of electromagnetic waves ranges from low-frequency radio waves to high-frequency gamma rays. Only a small portion of the spectrum, representing wavelengths of roughly 400-700 nanometers, is visible to the human eye.

© MERRIAM-WEBSTER INC.

electromagnetism Branch of physics that deals with the relationship between electricity and magnetism. Their merger into one concept is tied to three historical events. Hans C. Orsted’s accidental discovery in 1820 that magnetic fields are produced by electric currents spurred efforts to prove that magnetic fields can induce currents. Michael Faraday showed in 1831 that a changing magnetic field can induce a current in a circuit, and James Clerk Maxwell predicted that a changing electric field has an associated

magnetic field. The technological revolution attributed to the development of electric power and modem communications can be traced to these three landmarks.

electromotive force Energy per unit electric charge that is imparted by an energy source, such as an electric generator or a battery. As the device does work on the electric charge being transferred within itself, energy is converted from one form to another. The work done on a unit of electric charge or the energy gained by the unit charge is the electro¬ motive force emf (or E ) and is characteristic of any energy source capable of driving electric charge around a circuit. A common unit of electromo¬ tive force is the volt V, a unit equal to the difference in electric potential between two points in a conductor carrying a current of one ampere and dissipating one watt of power between the two points.

electromyography U-.lek-tro-ml-'ag-ro-feN Process of graphically recording the electrical activity of muscle, which normally generates an electric current only when contracting or when its nerve is stimulated. Electrical impulses are shown as wavelike tracings on an oscilloscope and recorded as an electromyogram (EMG), usually along with audible sig¬ nals. The EMG can show whether muscle weakness or wasting is due to nerve impairment (as in amyotrophic lateral sclerosis and poliomyelitis) or muscle impairment or disease (myopathy).

electron Lightest electrically charged subatomic particle known. It car¬ ries a negative charge (see electric charge), the basic charge of electricity. An electron has a small mass, less than 0.1% the mass of an atom. Under normal circumstances, electrons move about the nucleus of an atom in orbitals that form an electron cloud bound in varying strengths to the posi¬ tively charged nucleus. Electrons closer to the nucleus are held more tightly. The first subatomic particle discovered, the electron was identi¬ fied in 1897 by J. J. Thomson.

electron microscopy \ml-'kras-k3-pe\ Technique that allows exami¬ nation of samples too small to be seen with a light microscope. Electron beams have much smaller wavelengths than visible light and hence higher resolving power. To make them more observable, samples may be coated with metal atoms. Because electrons cannot travel very far in air, the elec¬ tron beam and the sample must be kept in a vacuum. Two different instru¬ ments are used. In the scanning electron microscope, a moving beam of electrons is scanned across a sample; electrons scattered by the object are focused by magnetic “lenses” to produce an image of the object’s surface similar to an image on a television screen. The images appear three- dimensional; they may be of small organisms or their parts, of molecules such as DNA, or even of large individual atoms (e.g., uranium, thorium). In the transmission electron microscope, the electron beam passes through a very thin, carefully prepared sample and is focused onto a screen or photographic plate to visualize the interior structure of such specimens as cells and tissues.

electron paramagnetic resonance See electron spin resonance

electron spin resonance (ESR) or electron paramagnetic resonance (ERR) Technique of spectroscopic analysis (see spectros¬ copy) used to identify paramagnetic substances (see paramagnetism) and investigate the nature of the bonding within molecules by identifying unpaired electrons and their interaction with their immediate surround¬ ings. Unpaired electrons, because of their spin, behave like tiny magnets and can be lined up in an applied magnetic field; energy applied by alter¬ nating microwave radiation is absorbed when its frequency coincides with that of precession of the electron magnets in the sample. The graph or spectrum of radiation absorbed as the field changes gives information valuable in chemistry, biology, and medicine.

electronic banking Use of computers and telecommunications to enable banking transactions to be done by telephone or computer rather than through human interaction. Its features include electronic funds transfer for retail purchases, automatic teller machines (ATMs), and auto¬ matic payroll deposits and bill payments. Some banks offer home bank¬ ing, whereby a person with a personal computer can make transactions, either via a direct connection or by accessing a Web site. Electronic bank¬ ing has vastly reduced the physical transfer of paper money and coinage from one place to another or even from one person to another.

electronic mail See E-mail

electronic music Any music involving electronic processing (e.g., recording and editing on tape) and whose reproduction involves the use

© 2006 Encyclopaedia Britannica, Inc.

610 I electronics ► elephant bird

of loudspeakers. In the late 1940s, magnetic tape began to be used, espe¬ cially in France, to modify natural sounds (playing them backward, at dif¬ ferent speeds, etc.), creating the genre known as musique concrete. By the early 1950s, composers in Germany and the U.S. were employing assembled conglomerations of oscillators, filters, and other equipment to produce entirely new sounds. The development of voltage-controlled oscillators and filters led, in the 1950s, to the first synthesizers, which effectively standardized the assemblages and made them more flexible. No longer relying on tape editing, electronic music could now be created in real time. Since their advent in the late 1970s, personal computers have been used to control the synthesizers. Digital sampling—composing with music and sounds electronically extracted from other recordings—has largely replaced the use of oscillators as a sound source.

electronics Branch of physics that deals with the emission, behaviour, and effects of electrons and with electronic devices. The beginnings of electronics can be traced to experiments with electricity. In the 1880s Tho¬ mas Alva Edison and others observed the flow of current between elements in an evacuated glass tube. A two-electrode vacuum tube constructed by John A. Fleming (1849-1945) produced a useful output current. The Audion, invented by Lee De Forest (1907), was followed by further improvements. The invention of the transistor at Bell Labs (1947) initi¬ ated a progressive miniaturization of electronic components that by the mid 1980s resulted in high-density microprocessors, which in turn led to tremendous advances in computer technology and computer-based auto¬ mated systems. See also semiconductor.

electrophile Atom or molecule that in a chemical reaction seeks an atom or molecule containing an electron pair available for bonding or the nega¬ tive end of a polar molecule (see covalent bond; electric dipole). In the Lewis electron theory (see acid-base theory) advanced by the U.S. chem¬ ist Gilbert Lewis (1875-1946) in 1923, electrophiles are by definition Lewis acids. Examples include the hydronium ion (H 3 0 + ), boron triflu¬ oride (BF 3 ), and the halogens fluorine, chlorine, bromine, and iodine in molecular form. See also acid; nucleophile.

electrophoresis Ni-.lek-tro-fo-'re-sosX Movement of electrically charged particles in a fluid under the influence of an electric field. The par¬ ticles migrate toward the electrode of the opposite electric charge, often on a gel-coated slab or plate, sometimes in a fluid flowing down a paper. Originated about 1930 by Arne Tiselius (1902-1971) as a technique for analysis, electrophoresis is used to analyze and separate colloids (e.g., pro¬ teins) or deposit coatings.

electroplating Process of coating with metal by means of an electric current. Plating metal may be transferred to conductive surfaces (e.g., metals) or to nonconductive surfaces (e.g., plastics, wood, leather) if a conductive coating has been applied. Usually the current deposits a given amount of metal on the cathode (workpiece) and the anode (source of metal) dissolves to the same extent, maintaining a fairly uniform solution. Silver plating is used on tableware, electrical contacts, and engine bear¬ ings. The most extensive use of gold plating is on jewelry and watch cases. Zinc coatings prevent the corrosion of steel articles, and nickel and chro¬ mium plate are used on automobiles and household appliances. See also TERNEPLATE, SHEFFIELD PLATE.

electrostatic induction Modification in the distribution of electric charge on one material under the influence of an electric charge on a nearby object. It occurs whenever any object is placed in an electric field. When a negatively charged object is brought near a neutral object, it induces a positive charge on the near side of the object and a negative charge on the far side. If the negative side of the original object is momen¬ tarily grounded, the negative charge may escape, so that the object becomes positively charged by induction.

electroweak theory Theory that describes both the electromagnetic force and the weak force. Though the forces appeal' to be different, they are actually different facets of a more fundamental force. This theory, for¬ mulated in the 1960s by Sheldon Glashow (bom 1932), Steven Weinberg (born 1933), and Abdus Salam (born 1926), represents a 20th-century sci¬ entific landmark and won its authors a 1979 Nobel Prize. It was validated in the 1980s with the discovery of the W particle and Z particle, which it had predicted. See also fundamental interaction, unified field theory.

electrum Natural or artificial alloy of gold with at least 20% silver, used to make the first known coins in the Western world. Most natural elec- trum also contains copper, iron, palladium, bismuth, and perhaps other

metals. The colour varies from white-gold to brassy, depending on the percentages of the major constituents and copper. The first Western coin¬ age, possibly begun by King Gyges of Lydia (7th century bc), consisted of irregular ingots of electrum bearing his stamp as a guarantee of nego¬ tiability at a predetermined value. See also coinage.

elegy Ve-l9-je\ Meditative lyric poem. The classical elegy was any poem written in elegiac metre (alternating lines of dactylic hexameter and pen¬ tameter). Today the term may refer to this metre rather than to content, but in English literature since the 16th century it has meant a lament in any metre. A distinct variety with a formal pattern is the pastoral elegy, such as John Milton’s “Lycidas” (1638). Poets of the 18th-century Grave¬ yard School reflected on death and immortality in elegies, most famously Thomas Gray’s “An Elegy Written in a Country Church Yard” (1751).

element, chemical One of the more than 110 presently known kinds of substances that constitute all matter at and above the level of atoms (the smallest units of any element). All atoms of an element are identical in nuclear charge (number of protons) and number of electrons (see atomic number), but their mass (atomic weight) may differ if they have different numbers of neutrons (see isotope). Each permanently named element has a one- or two-letter chemical symbol. Elements combine to form a wide variety of compounds. All elements with atomic numbers greater than 83 (bismuth), and some isotopes of lighter elements, are unstable and radio¬ active (see radioactivity). The transuranium elements, with atomic numbers greater than 92 (see uranium), artificially created by bombardment of other elements with neutrons or other particles, were discovered beginning in 1940. The most common elements (by weight) in Earth’s crust are oxy¬ gen, 49%; silicon, 26%; aluminum, 8%; and iron, 5%. Of the known ele¬ ments, 11 (hydrogen, nitrogen, oxygen, fluorine, chlorine, and the six noble gases) are GASes under ordinary conditions, two (bromine and mer¬ cury) are liquids (two more, cesium and gallium, melt at about or just above room temperature), and the rest are solids. See also periodic table. See illustration and table on following pages.

elementary education or primary education Traditionally, the first stage of formal education, beginning at age 5-7 and ending at age 11-13. Often preceded by some form of preschool, it usually includes middle school, or junior high school (ages 11-13), though this is some¬ times regarded as part of secondary education. Nearly all nations are com¬ mitted to some form of elementary education, though in many developing countries many children are unable to continue full-time studies past the age of 10 or 11. The elementary curriculum usually emphasizes reading and writing, arithmetic, social studies, and science. A basic teaching strat¬ egy involves moving the student from the immediate and familiar to the distant and unfamiliar, an approach first formulated by Johann Heinrich Pestalozzi.

elementary particle See subatomic particle

elephant Any of three ungulate species in the order Proboscidea (fam¬ ily Elephantidae), characterized by their large size, long trunk, tusks, massive legs, large ears, and huge head. All species are grayish to brown, with sparse, coarse body hair.

The trunk is used for breathing, drinking, and reaching for food.

Elephants eat grasses, leaves, and fruit. The African savanna, or bush elephant (Loxodonta africana ), of sub-Saharan Africa, is the largest liv¬ ing land animal, weighing up to 16,500 lbs (7,500 kg) and standing Asian elephant [Elephas maximus).

10-13 ft (3-4 m) tall at the shoulder. ES ROSS _

The African forest elephant (L.

cyclotis) is smaller. The Indian elephant (Elephas maximus ), of South and Southeast Asia, weighs about 12,000 lbs (5,500 kg) and stands about 10 ft (3 m) tall. Elephants live in habitats ranging from thick jungle to savanna, in small family groups led by old cows. Most bulls live in bach¬ elor herds. Elephants migrate seasonally. They may eat more than 500 lbs (225 kg) of vegetation daily. All species are considered endangered by the International Union for Conservation of Nature and Natural Resources (IUCN).

elephant bird See aepyornis

© 2006 Encyclopaedia Britannica, Inc.

Elephant Man ► elevator I 611

T3

O

a3

Q.

group

1 *

la**

PERIODIC TABLE OF THE ELEMENTS

18

0

1

2

□

alkali metals

[” | other nonmetals 0 noble gases

13

14

15

16

17

2

H

1 la

■

alkaline earth metals

0 halogens

| actinide elements

Ilia

IVa

Va

Via

Vila

He

3

4

□

transition metals Q rare earth elements (21,39, 57-71)

5

6

7

8

9

10

Li

Be

B

other metals

lanthanide elements (57-71 only)

B

C

N

O

F

Ne

11

12

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

Na

Mg

nib

IVb

Vb

Vlb

Vllb

-Vlllb-

lb

lib

Al

Si

P

S

Cl

Ar

19

20

21

22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

K

Ca

Sc

Ti

V

Cr

Mn

Fe

Co

Ni

Cu

Zn

Ga

Ge

As

Se

Br

Kr

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

Rb

Sr

Y

Zr

Nb

Mo

Tc

Ru

Rh

Pd

Ag

Cd

In

Sn

Sb

Te

1

Xe

55

56

57

72

73

74

75

76

77

78

79

80

81

82

83

85

86

Cs

Ba

La

Hf

Ta

W

Re

Os

Ir

Pt

Au

Hg

TI

Pb

Bi

Po

At

Rn

87

88

89

104

105

106

107

108

109

110

111

112

113

114

115

116

Fr

Ra

Ac

Rf

Db

sg

Bh

Hs

Mt

Ds

Rg

(Uub)

(Uut)

(Uuq)

(Uup)

(Uuh)

lanthanide series

6

actinide series

7

Numbering system adopted by the International Union of Pure and Applied Chemistry (IUPAC).

** Numbering system widely used, especially in the U.S., from the mid-20th century.

*** Discoveries of elements 112-116 are claimed but not confirmed. Symbols in parentheses are temporarily assigned by IUPAC.

58

59

60

61

62

63

64

65

66

67

68

69

70

71

Ce

Pr

Nd

Pm

Sm

Eu

Gd

Tb

Dy

Ho

Er

Tm

Yb

Lu

90

91

92

93

94

95

96

97

98

99

100

101

102

103

Th

Pa

U

Np

Pu

Am

Cm

Bk

Cf

Es

Fm

Md

No

Lr

The periodic table arranges the elements into groups (vertically) of elements sharing common physical and chemical characteristics, and into periods (horizontally) of sequentially increasing atomic number and electron-shell configuration. Elements 112-116 are reported to have been created experimentally but have not yet received per¬

manent names.

© MERRIAM-WEBSTER INC.

Elephant Man orig. Joseph (Carey) Merrick (b. Aug. 5, 1862, Leicester, Leicestershire, Eng.—d. April 11, 1890, London) Englishman disfigured by a disease that caused growths over his skin and bone sur¬ faces. His head was 3 ft (.9 m) around, with large bags of skin hanging from it, the jaw so deformed he could not speak clearly. One arm ended in a 12-in. (.3-m) wrist and a finlike hand. His legs were similarly deformed, and a defective hip made him lame. He escaped from a work- house at 21 to join a freak show, where a London physician, Frederick Treves, discovered him and admitted him to London Hospital. He died in his sleep at 27 of accidental suffoca¬ tion. His disease was probably the very rare Proteus syndrome. A suc¬ cessful play and film were based on Merrick’s life.

elephant seal Either of the two largest pinniped species: the northern elephant seal (Mirounga angustiros- tris), of coastal islands off California and Baja California, or the southern elephant seal (M leonina ), of sub- Antarctic regions. Both are gregari¬ ous earless seals. The male has an inflatable, trunklike snout. The northern species is yellowish or gray-brown, the southern species blue-gray. Males of both species reach a length of about 21 ft (6.5 m) and a weight of about 7,780 lbs

(3,530 kg) and are much larger than the females. Elephant seals feed on fish and squid or other cephalopods. During the breeding season, bulls fight to establish territories along beaches and to acquire harems of up to 40 cows.

Eleusinian Mysteries \,el-yu-'si-ne-3n\ Most famous mystery reugion of ancient Greece. It was based on the story of Demeter, whose daughter Persephone was kidnapped by Hades. While searching for her daughter, Demeter stopped at Eleusis, revealed her identity to the royal family, and taught the natives her rites. The Greater Mysteries were celebrated in autumn, beginning with a procession from Athens to the temple at Eleu¬ sis. This was followed by a ritual bath in the sea, three days of fasting, and completion of secret rites. Initiates were promised personal salvation and benefits in the afterlife.

Eleusis \i-'lu-s3s\ Greek Elevsis \,e-lef-'ses\ Town, with ruins of an ancient city, eastern Greece. Famous as the site of the Eleusinian Myster¬ ies, it is about 14 mi (23 km) west of Athens. It was independent until the 7th century bc, when Athens annexed the city and made the Eleusinian Mysteries a major Athenian religious festival. The Gothic leader Alaric destroyed Eleusis in ad 395. Deserted until the 18th century, it was revived as the modern town of Eleusis (Greek Lepsina), now a suburb of Athens. Some of the ruins have been excavated, including the Hall of Initiation, which dates back some 3,000 years to late Mycenaean times.

elevator Car that moves in a vertical shaft to carry passengers or freight between the levels of a multistory building. The use of mechanical lift¬ ing platforms dates to Roman times. Steam and hydraulic elevators came into use in the 19th century; electric elevators had been introduced by the end of the century. Most modem elevators are electrically propelled through a system of cables and pulleys with the aid of a counterweight, though hydraulic elevators are still used in low buildings. The introduc-

© 2006 Encyclopaedia Britannica, Inc.

612 I Elgar ► Elgin

Element

Symbol

Atomic no.

Atomic weight*

Element

Symbol

Atomic no.

Atomic weight*

Actinium

Ac

89

227.028

Molybdenum

Mo

42

95.94

Aluminum

Al

13

26.9815

Neodymium

Nd

60

144.24

Americium

Am

95

(243)

Neon

Ne

10

20.180

Antimony

Sb

51

121.75

Neptunium

Np

93

237.0482

Argon

Ar

18

39.948

Nickel

Ni

28

58.69

Arsenic

As

33

74.9216

Niobium

Nb

41

92.9064

Astatine

At

85

(210)

Nitrogen

N

7

14.0067

Barium

Ba

56

137.33

Nobelium

No

102

(259)

Berkelium

Bk

97

(247)

Osmium

Os

76

190.2

Beryllium

Be

4

9.01218

Oxygen

O

8

15.9994

Bismuth

Bi

83

208.9804

Palladium

Pd

46

106.42

Bohrium

Bh

107

(264)

Phosphorus

P

15

30.97376

Boron

B

5

10.81

Platinum

Pt

78

195.08

Bromine

Br

35

79.904

Plutonium

Pu

94

(244)

Cadmium

Cd

48

112.41

Polonium

Po

84

(209)

Calcium

Ca

20

40.08

Potassium

K

19

39.0983

Californium

cf

98

(251)

Praseodymium

Pr

59

140.9077

Carbon

C

6

12.011

Promethium

Pm

61

(145)

Cerium

Ce

58

140.12

Protactinium

Pa

91

231.0359

Cesium

Cs

55

132.9054

Radium

Ra

88

226.0254

Chlorine

Cl

17

35.453

Radon

Rn

86

(222)

Chromium

Cr

24

51.996

Rhenium

Re

75

186.207

Cobalt

Co

27

58.9332

Rhodium

Rh

45

102.9055

Copper

Cu

29

63.546

Roentgen ium

R g

111

(272)

Curium

Cm

96

(247)

Rubidium

Rb

37

85.4678

Darmstadtium

Ds

110

(271)

Ruthenium

Ru

44

101.07

Dubnium

Db

105

(262)

Rutherfordium

Rf

104

(261)

Dysprosium

Dy

66

162.50

Samarium

Sm

62

150.36

Einsteinium

Es

99

(252)

Scandium

Sc

21

44.9559