Excerpts from Exploring the Chemical Elements ...

Excerpts from:

Exploring the Chemical Elements and their Compounds by David L. Heiserman

From the Introduction
Introduction

As a junior-high school science student contemplating a science fair project, I came across a book in our public library that described chemical elements and their compounds. The book was very technical and very, very thick as I remember it. I understood very little of the material it contained, but I was quite taken with descriptions of colors, textures and especially the endless variety of chemical reactions. That mental snapshot of the past turned out to be the seed for writing a book on the same topic, but one that is less technical, not quite as thick and much easier to understand.

Element 1
Hydrogen

The hydrogen atom is the simplest atom that can possibly exist. Its most common isotope is composed of a single proton and an electron; and if you take away either of these parts, you no longer have an atom at all.

Element 2
Helium

Helium was discovered in the sun before it was found on earth. It is a harmless gas which, when inhaled, makes you talk like Donald Duck.

Element 3
Lithium

Lithium is the lightest of all metals. Solid metallic lithium weighs about the same as a piece of ordinary dry wood of the same volume, and this metal does in fact float on water. It is not recommended that you try floating your only sample of metallic lithium on water, though. Lithium reacts rather vigorously with water to form hydrogen gas and lithium hydroxide.

Element 4
Beryllium

Beryllium is also known as glucinum, or "sweet." The reason is that beryllium metal and many of its compounds have a sugary taste. It is not a good idea to go around tasting beryllium, however, because it is a deadly poison. Exposure to its dust particles has been identified as the source of a painful disease known as berylliosis.

Element 5
Boron

Few people through the history of the chemical elements regarded borax as an element, even though no one could figure out what its essential components were.

Element 6
Carbon

There is more of the less-familiar element, titanium, in the earth than carbon. The earth is indeed a strange place, then, because carbon is the sixth most-abundant atom in the cosmos

Element 7
Nitrogen

Nitrogen is by far the most abundant gas in the earth's atmosphere. Every breath you take is nearly 80 percent nitrogen.

Element 8
Oxygen

The most important application of oxygen comes to all of us free of charge--as free as the air we breathe, so to speak. Commercially speaking, the U.S. annually produces some 15-million tons of liquid oxygen for applications in industry, aerospace, the military and medicine. Oxygen is important to life, and it is big business.

Element 9
Fluorine

Fluorine is an element of extremes. On one hand, it is an extremely active, gassy element that combines spontaneously and explosively with hydrogen to produce hydrogen fluoride--an acid commonly used for etching glass. But on the other hand, fluorine mixed in a proportion of about 1 part-per-million of water helps prevent cavities in teeth. Compounds of fluorine are also added to toothpastes to aid in the reduction of cavities.

Element 10
Neon

Sir William Ramsay and Morris W. Travers were still rejoicing over their discovery of krypton gas in May of 1898 when they unveiled yet another one, neon. Ramsay believed he had unlocked a pattern of elements on the periodic table. Once a pattern is suggested, one knows what to look for; and when one knows what to look for, one certainly has a better chance of finding it.

Element 11
Sodium

By 1758, chemists were getting close to isolating sodium metal. Considering the explosive manner in which sodium reacts to oxygen and moisture in the air, early experiments aimed at isolating the metal usually included some thinly disguised excitement about how the substances detonated, flashed, cumbusted and otherwise made life a bit more interesting around the old laboratory.

Element 12
Magnesium

The history of magnesium begins in 1618 when a farmer's cows refused to drink water from a certain mineral well in Epsom, England. Once the farmer tasted the bitterness of the water, he couldn't blame the cows for not drinking it; but he found that the water had some positive healing effects on scratches and rashes on his skin. There was no TV, radio nor U.S.A. Today in those days, so ad campaigns got off to a slow start. Nevertheless, the well at Epsom eventually became a world-wide commercial success. The well at Epsom could not supply the demand, so entrepreneurs began working the "bitter salts" out of wells in Limington and Portsea Island. Then, as now, the product was called Epsom salt, regardless of its origin.

Element 13
Aluminum

Aluminum is the most abundant metal on the surface of the earth, exceeded only by the non- metals, oxygen and silicon. Even so, its existence remained a secret until the late 1700s.

Element 14
Silicon

Daydreaming about silicon might bring up two thoughts: warm sandy beaches and electronic semiconductors ... or maybe the cooler beaches of Northern California and nearby Silicon Valley. Perhaps some people think of window glass--that's made of silicon, too. On the average, 282- thousand out of 1- million atoms of the earth's crust are silicon atoms. That's better than one out of four; and silicon dioxide, or common beach sand, accounts for nearly half of that share.

Element 15
Phosphorus

The following account of Brand's procedure for producing phosphorus is taken from W. Derham's 1726 edition of Philosophical Experiments and Observations of the Late Eminient Dr. Robert Hookes, F.R.S. and Geom Prof. Gresh and Other Eminent Viruoso's in His Time and as presented in Weeks and Leicester's Discovery of the Elements (1968).

"Take a quantity of Urine (not less for one Experiment than 50 or 60 Pails full); let it lie steeping in one or more Tubs, ...til it putrify and breed Worms, as it will do in 13 or 14 days. Then, in a large Kettle, set some of it to boil on a strong Fire, and, as it consumes and evaporates, pour in more, and so on, till, at last, the whole Quantity be reduced to a Paste...then evaporate all in warm Sand, and there will remain a red, or reddish, Salt. Take this Salt, put it into a Retort, and, for the first Hour, begin with a small Fire; more the next, a greater the 3d, and more the 4th; and then continue it, as high as you can, for 24 Hours. Sometimes, by the Force of the Fire, 24 Hours proves enough; for when you see the Recipient white, and shining with Fire, and that there are no more Flashes, or, as it were, Blasts of Wind, coming from Time to Time from the Retort, then the Work is finished. And you may, with Feather, gather the Fire together, or scrape it off with a Knife, where it sticks."

Durham later describes how, "...he had once wrapp'd up a Knob [of white phosphorus] in Wax, at Hanover, and it being in his Pocket, and he busy near the Fire, the very Heat set it in Flame, and burn'd all his Cloaths, and his Fingers also, for through he rubbed them in the Dirt, nothing would quench it, unless he had Water; he was ill for 15 Days, and the Skin came off ."

Element 16
Sulfur

Sulfur, even in its pure elemental form, is a rather common substance. It is generally characterized as a pale yellow, brittle solid that has no taste. It isn't supposed to have an odor, either; but common experience suggests otherwise. Actually pure sulfur has no odor--the distinctive, biting aroma is actually that of sulfur dioxide which forms in small amounts when sulfur comes into contact with oxygen and moisture in the air.

Element 17
Chlorine

Chlorine exists as a greenish-yellow, highly corrosive gas at room temperature. It is essential that you avoid inhaling even the smallest dose of concentrated chlorine gas. If you want to get some appreciation for its suffocating odor, you can xperience it at safe concentrations around large swimming pools and in areas where someone is using chlorine bleach.

Element 18
Argon

Argon is a member of the Group-0 elements. Until the late 1960s, this group was often called the inert gasses because it was believed they could not possibly combine with any other element to form compounds. Today we know that the so-called inert gasses can indeed combine with other elements. Admittedly, it is difficult to create these compounds; most of them are highly unstable, some barely qualify as being compounds at all, and none of them has any practical application. In the world of theoretical chemistry where truth and knowledge is more important that an improved shoe polish, the notion that the noble gasses can combine with other elements is one of the most satisfying discoveries of this generation.

Element 19
Potassium

Pure potassium metal is so soft that many who have worked with it refer to it as a "waxy" substance. Few people have had such an opportunity, however, because potassium is highly unstable in the normal human environment. It reacts with the oxygen in dry air to produce the potassium superoxide, KO₂. If there is any moisture in that air, or if the sample of potassium comes into direct contact with water, you get potassium hydroxide, (KOH) and hydrogen gas.

2K + 2H₂O --> 2KOH + H₂
(potassium + water potassium hydroxide + hydrogen gas)
This reaction is exothermic. That is, it generates heat ... enough heat in this case to ignite the hydrogen gas.

Element 20
Calcium

Calcium was virtually unknown as a chemical element until the 19th century. However, limestone and gypsum, the principal minerals of calcium, have been applied, studied and understood from ancient times. For example, some ancient Egyptian tombs are lined with a form of gypsum plaster which is essentially the same as the drywall product developed for modern-day building construction.

Element 21
Scandium

The existence of scandium was predicted theoretically by Mendeleyev in 1871. He suggested it would resemble boron, so he gave the undiscovered metal the name ekaboron and suggested the chemical symbol, Eb. Furthermore, Mendeleyev predicted Eb would have an atomic weight of 44 (atomic weight of Sc is 44.9), its oxide would have a specific gravity of 3.5 (the scandium oxide has a specific gravity of 3.86), the carbonate would be insoluble in water (the Sc carbonate is indeed insoluble), and the element would not be discovered spectroscopically (and it wasn't). Mendeleyev did not have to consult a crystal ball nor get some mystical peek into the future in order to suggest the existence of a new chemical element and predict its properties. He did something that is rarely regarded as expedient these days--hard work and serious creative thinking.

Element 22
Titanium

Titanium is closely associated with strong, corrosion- resistant metals that find esoteric applications in the military and aerospace industries. Although it is indeed a valuable metal, it is neither esoteric nor particularly hard to find. Titanium dioxide (TiO2) is an intensely white powder that is often used as a paint pigment called titanium white. Titanium tetrachloride (TiCl4) generates a dense white vapor when it reacts with moist air. It is used as a liquid smoke-producing product for skywriting and military smoke-screen devices.

Element 23
Vanadium

In 1801, Andrs Manuel del Rio, a professor of mineralology in Mexico City found traces of a heretofore unknown element in samples of brown lead from a mine near Hidalgo in northern Mexico. Circumstances, personalities and human error, however, combined to shake del Rio's confidence in his discovery. Things began to turn sour when the parcel post system of the time failed him. His samples of brown lead ore were sent to the Institut de France in Paris for analysis and confirmation. A brief explanation accompanying the samples was ambiguous, pointing out the similarity between the new element and chromium. A complete analysis and description of his laboratory were lost in a shipwreck. So the Institut saw nothing but a jar of brown lead and a brief note explaining how much the new stuff resembled chromium. The unfortunate professor gave up his fight, and the academic world readily accepted his apology for being so silly and unprofessional. Thirty years later, de Rio was give proper credit for his discovery, but one has to wonder how many brilliant discoveries have been lost because of discouragement in the face of adverse circumstances, and because one concedes to the opinions of his peers and those to imagine themselves to be peers.

Element 24
Chromium

A chromium ore, sometimes called Siberian red lead, was a popular pigment for brilliant red oil paints in the 18th century. Other compounds produce pigments of other popular colors, including chrome oxide green and lead chromate yellow.

Element 25
Manganese

The suggestion that manganese might be a basic chemical element was part of a most remarkable dissertation presented to the Stockholm Academy by Carl Wilhelm Scheele in 1774. The dissertation not only spelled out the chemical nature of manganese for the first time, but suggested the existence of chlorine, oxygen and barium. That's four new elements described in a single paper!

Element 26
Iron

Iron is of ancient origin. The oldest iron artifacts, a few bits of smelted iron, have been dated at 3000 years B.C. The Egyptians knew how to mine, refine and work iron. There are numerous reference to iron mines, furnaces and iron objects in the Old Testament. Unfortunately, iron objects, themselves, corrode rather readily. So evidence for ancient applications of iron is written, rather than direct, evidence.

Element 27

Cobalt

By the middle of the 16th century, chemists and mineralogists were referring to the mineral that produced blue glass and pigments as zaffer. German miners who had to cull the stuff out of the ground called it "kobald," referring to their mythological imp that caused the day-to- day difficulties of the mining profession. (The thinking is not unlike the "bugs" we say get into our modern high-tech equipment and computer software). By the 18th century, the mineral was being called cobalt instead of zaffer.

Element 28
Nickel

Nickel is a hard, malleable and ductile metal. It has a silvery white appearance, and it can be polished to a lustrous finish. Corrosion under normal environmental conditions is practically non-existent, making nickel a natural choice for a coinage material.

Element 29
Copper

The American slang expression for a policeman, cop or copper, probably has its origin in the fact that U.S. policemen once wore uniform buttons made of copper.

Element 30
Zinc

Zinc is relatively resistant to corrosion due to reactions with oxygen and moisture in the atmosphere. A thin layer of zinc applied to iron or steel products tends to extend their useful life by protecting them (at least for a reasonable period of time) from corrosion. When the zinc coating is applied by an electrolytic process, the product said to be galvanized.

Element 31
Gallium

Gallium was an obscure metal that was known only to chemistry professors and people interested in science trivia. But that all changed in the early 1970 when gallium arsenide (GaAs) light-emitting diodes, or LEDs, exploded onto the electronics scene.

Element 32
Germanium

The existence of germanium was predicted theoretically by Mendeleyev in 1871. He suggested it would resemble silicon, so he gave the undiscovered metal the name ekasilicon and suggested the chemical symbol, Es. Furthermore, Mendeleyev predicted Es would have an atomic weight of 72 (atomic weight of Ge is 72.59), the specific gravity would be 5.5 (germanium has a specific gravity of 5.32). There were other predictions about Mendeleyev's ekasilicon that fit the specifications for germanium when it was finally found.

Element 33
Arsenic

Some compounds of arsenic, called arsenides, are used in the manufacture paints, wallpapers and ceramics. Arsenic is also used as a weed killer and rat poison; and, of course, there are the more sinister applications described in the histories of crime. At one time, arsenic (actually arsenious oxide) was once a popular poison for the homicidially inclined. Injesting arsenic in small doses over a period of time, the victim would develop symptoms similar to those of pneumonia, then die without a trace of any known poison in his body. Intentional arsenic poisoning is rare these days, however, because coroners have found techniques for detecting its presence during an autopsy.

Element 34
Selenium

The conductivity of pure selenium can increase as much as a 1000-fold when a sample is taken from darkness into bright sunlight. This property accounts for selenium being found in all kinds of light- sensitive devices, from robotic sensors to xerography machines.

Element 35
Bromine

In 1825, a freshman chemistry student at Heidelberg walked up to his professor and showed him a container of a red, chlorine-smelling liquid. Freshmen these days bring small refrigerators, portable TVs, teddy bears and poor posture from home. Young Carl Lwig brought a new chemical element he had concocted at home during his summer break. His professor, Leopold Gmelin didn't know what the smelly liquid was, but he knew it didn't belong to the world of common chemicals.

Element 36
Krypton

Any resemblance between the element krypton and Superman's strength-sapping nemesis, kryptonite, is purely coincidental. Or maybe the people who thought of the names were thinking of the Greek word for "hidden." Nevertheless, krypton, the element, is a very real atmospheric gas.

Element 37
Rubidium

Rubidium is one of the few metals that can exist in its liquid form in a natural environment (if you happen to consider 39C, or 102F, a natural environment). You can melt rubidium metal in your hand if you happen to have a fever; and if you are technically inclined, you can substitute the expression, "It's hot enough to fry an egg on the sidewalk," with "It's hot enough to melt rubidium on the sidewalk."

Element 38
Strontium

Strontium has two faces: a good face and a bad one. On the positive side, the salts of strontium produce brilliant red flames that are at the heart of many kind sof pyrotechnic device. On the negative side, the strontium-90 isotope is a deadly and long-lived fallout product of atomic-bomb explosions.

Element 39
Yttrium

Yttrium is a rare-earth metal that is no longer regarded as a rarity. It is one of the most abundant rare-earth elements; and the supply meets the commercial demand for its oxide: more than 15 tons per year. The best-known application is as phosphor that produces the brilliant red color available with today's color televsion tubes.

Element 40
Zirconium

Zirconium minerals have been known since ancient times, but more so by their older names, jargon, jacinth and hyacinth. Jacinth, for example, is mentioned three times in the Bible. No one suspected that these minerals might contain an undiscovered chemical element until Martin Heinrich Klaproth (1743-1817) took a good look at the mineral during the closing years of the 1700s.

Element 41
Niobium

Not many people have heard of niobium, and some prefer to call it columbium. It was discovered in a museum and mistaken for a compound of chromium. Later it was determined to be tantalum, and not an element at all. If niobium were a person, we might say he or she would suffer from a serious problem with personal identity.

Element 42
Molybdenum

During WWII, the German army constructed a giant piece of artillery that was moved about as desired on a railroad car. The Allies called the gun Big Bertha, and sood discovered that the special formulation for the gun steel included molybdenuma metal that previously had no practical application. Now we know that "moly steel" was another important technological advance brought about by modern warfare.

Element 43
Technetium

Technetium is unusual in a couple of respects. First, it is one of the very few artifically produced elements that has a practical industrial application. Second, technitium is unusual insasmuch as portions as small as 55 parts-per-million can transform ordinary iron into a corrosion-resistant alloy.

Element 44
Ruthenium

Element 44 was first isolated by Jedrzej Sniadecki (1768- 1838) in 1807. He authored several papers and a book about his new element and his procedures for isolating it. Being relatively unknown in the scientific community, his claims were not immediately accepted by the Paris commission. The members of that commission, in fact, were unable to find the new element among ores of platinum as Sniadecki described. Rather than suggesting the panel of big shots in Paris weren't doing their job right, this undistinguished Polish professor quietly withdrew his claims. And in big-time science, withdrawing a claim is tantamount to saying nothing had ever happened. Other, better-known scientists will later get credit for finding and isolating the element; but it can be shown today that Sniadecki had done the complete job much earlier. Which just goes to show you that you can't win a race you quit.

Element 45
Rhodium

The entire world production of rhodium is on the order of 10 tons per year. Some is used in the manufacture of special high-temperature crucibles for laboratory applications; most, however, is used as a hardener for platinum and palladium.

Element 46
Palladium

Palladium is not a very familiar element, but it has some applications to familiar objects. This soft, corrosion- resistant metal is frequently used as a substitute for silver in dental items and jewlry; but it stands on its own as the delicate mainsprings in mechanical wristwatches.

Element 47
Silver

Silver is of ancient origin, with products and refining methods described in the Bible and early Egyptian writings. There was a period in early history when silver was regarded more highly than gold, probably because gold was easier to locate and refine at the time. We now know that silver is ten times more abundant in the earth's crust than gold.

Element 48
Cadmium

Cadmium is a rather scarce for a metal that has everyday industrial applications. People don't have to go out looking for cadmium ore, however, because the element turns up in every truckload of common zinc ore. So a company that refines ordinary zinc can recover significant amounts of cadmium as a by-product.

Element 49
Indium

In 1863, Ferdinand Reich (1799-1882) was seaching for traces of the newly discovered element, Thallium, in zinc ores from the nearby Himmelsfrst mine. Some chemical treatments convinced Reich he had accidentally produced the yellowish sulfide of a new element. The situation required a spectroscopic examination of the samples in order to confirm the presence of a new element. Spectroscopic work was routine in those days, and the bands of colors, fingerprints as it were, provided conclusive qualitative analysis. Reich was on the verge of success, but he suffered from a particularly annoying handicap: he was totally colorblind. So Reich had to entrust the spectrographic analysis to an assistant named Hieronymous Theodor Richter. Using a simple spectrographic setup, Richter was the first to see the bright indigo lines of the new element. Co-discoverers, Reich and Richter, thus named it indium.

Element 50
Tin

Tin is perhaps best known for its use in the manufacture of "tin cans." A very thin coating of tin on steel food containers prevents corrosion that would otherwise spoil the contents. Tin is an ideal metal for this application because it is non-toxic, non-corrosive and can be easily applied to the surface of other metals. Tin cans are no longer as widely used as they once were, however, being replaced in many instances by containers made from less expensive materials such as plastic and paper.

Element 51
Antimony

Antimony is one of the few elements that was studied, mined and applied during the opening centuries of recorded history. It is unusual that an element having such a long history is so little known today. Few people can name a single application nor a common item that uses antimony.

Element 52
Tellurium

In the latter part of the 1770s, Franz Joseph M�ller von Reichenstein was appointed chief inspector of all mines, smelters and saltworks in the tiny province of Transylvania. Possessing something more than a bureaucrat's passing interest in the subject of his work, M�ller began experimenting with the ores from his mines. An ore of gold, known as the time as aurum album, caught his attention when he extracted a different metal from it. He and other chemists working on similar samples assumed it to be antimony. By 1783, M�ller was beginning to think the metal was not antimony at all, but a new metal later to be called tellurium.

Element 54
Xenon

Most people never get around to discovering a new element, few have discovered three of them, and even fewer have discovered three new elements in as many consecutive months; but Sir William Ramsay (1852-1916) and Morris William Travers (1872-1961) pulled off the hat trick in May, June and July of 1898. The elements they added to the periodic table were krypton (May 30), neon (sometime in June) and xenon (July 12, 1898).

Element 55
Cesium

Its name is taken from the Latin csius, "sky blue"; named for the characteristic blue lines of its spectrum.

Element 56

Barium

The historical background for barium is just about as varied and colorful as its modern-day applications--from the eerie, glowing Bologna stone of sixteenth-century alchemists to the modern day technology of ultrasonics.

Element 57
Lanthanum

Today we know that all sixteen of the naturally occurring rare earths are found mixed together in their oxide forms, but that was not known in the last decades of the 1800s. At that time, there were just two rare-earth oxides, yttria and ceria. Carl Gustav Mosander and others saw the possibility that their samples of yttria and ceria were not absolutely pure, so they set out to look for the impurities. In 1839, for example, Mosander obtained some cerium nitrate and treated it with dilute nitric acid. The reaction yielded a new oxide which Mosander called lanthana. So the cerium was indeed contaminated with a new element--one we now call lanthanum.

Element 58
Cerium

Cerium is a shiny gray, malleable, soft and ductile metal. It readily oxidizes in moist air and decomposes rapidly in hot water. The heat of friction caused by scratching a sample of the pure metal can ignite it.

Element 59
Praseodymium

The most critical application of praseodymium is as a high- strength alloying agent in the magnesium used in parts of modern aircraft engines. Misch metal, an important alloying agent in steel and a "flint" for creating sparks, contains about 5% praseodymium metal. The yellow didymium glass used in welder's goggles contains a mixture of praseodymium and neodymium.

Element 60
Neodymium

The technical skills of one Baron Auer von Welsbach (1858-1929) paid off in June, 1885, when he announced to the Vienna Academy of Sciences that he had split a relatively common earth called didymium into two new earths. He called the two new elements praseodymia (green didymia) and neodymia (new didymia), which are now known as praseodymium and neodymium, respectively.

Element 61
Promethium

The spectral lines of promethium have been observed in the light from some stars, but it is a well established fact that this element does not occur naturally on the earth. So as provincial as it might seem, earthling chemists regard prometheium as a synthetic element.

Element 62
Samarium

Samarium is easily magnetized and, as far as anyone knows at this time, no other material is more difficult to demagnetize. This property suggests important applications in solid-state and superconductor technologies.

Element 64
Gadolinium

Gadolinium has the capacity for absorbing larger concentrations of thermal neutrons than any other naturally occurring element. This makes it an ideal material for control rods in nuclear power generators.

Element 65
Terbium

Terbium is definitely not a household word. It's a safe bet that most students in high school and first-year college chemistry classes would not recall hearing anything about it. It ranks 14th in abundance among the seventeen rare earths in the earth's crust ... where you can expect to find one teaspoon of the element for every 63 tons of earth.

Element 66
Dysprosium

The name is taken from the Greek word dysprositos, "hard to get at."

Element 67
Holmium

For a short time prior to its acceptance as an element, holmium was known in some circles as Element X.

Element 68
Erbium

Erbium ranks eleventh out of seventeen on the abundance chart of rare earths in the earth's crust. Having an average concentration of 2.5 parts-per million, you might expect to find 2.5 pounds of erbium in every million pounds (500 tons) of dirt, mud and clay. These are average estimates, however; erbium, like all of the other rare earths, are found in much higher concentrations in a few scattered localities. So if you dig in the wrong place, you won't find any erbium in 500 tons of earth. Dig in the right place, though, and you might find nearly a ton of it.

Element 69
Thulium

Thulium is the least abundant of the naturally occurring rare earths. It is found in average portions of 0.2 parts per million of the earth's crust. This means you have to dig through 5000 tons of earth to find just 2 pounds of thulium. The only rare earth that is any rarer is promethium, and that one doesn't exist on earth at all.

Element 70
Ytterbium

Finally, the is a confusion of names for ytterbium. It is also known by two other names, aldebaranium and cassiopeium; and the proper name is easily confused with the name of a other rare-earth element, yttrium (atomic number 39).

Element 71
Lutetium

Lutetium is an element that has had a lot of different names: neoytterbium, lutecium, cassiopeium and lutetium. Of those four names, the last two are still in use today. And having so many names, one might suspect that an element that has so many different names must certainly be important. But it isn't. In fact Lutetium is one of the few natural elements that has no practical application.

Element 72
Hafnium

The existence of hafnium was suspected in the latter part of the 1800s. A researcher studying zirconium sulfate during that era remarked, "Zirconium is not simple; there is another element concealed in it, and when I have leisure I shall endeavor to isolate it." Unfortunately, there is usually a wide gulf between one who first perceives a truth and one who reaps the fruit of it. This particular perceiver of truth, one F.A. Genth, apparently never found the necessary leisure because he died some thirty years before anyone found a way to separate the hidden element from zirconium.

Element 73
Tantalum

Tantalum comprises only 0.0002% of the earth's crust, and most of it is concentrated in ores from South America, Africa, and Spain. The United States has very little native tantalum ore, but is the world's leading consumer.

Element 74
Tungsten

Tungsten was originally called wolfram. This was back in the late 1700s when it was discovered. In fact a few conservative German journals prefer to call element 74 by its original name. Wolfram is an appropriate name because the mineral, wolframite, played an important role in the discovery of this element.

Element 75
Rhenium

Rhenium is also noted for being one of rarest of the naturally occurring elements. You have to dig up 1000-million pounds of the earth's crust in order to get one pound of rhenium out of it. The total U.S. annual production of rhenium is almost a half ton, and the total world reserves is on the order of 400 tons.

Element 76
Osmium

The oxides of osmium emit highly toxic gasses; and since these oxides form readily when the metal is exposed to air, there are few commercial applications of the element, itself.

Element 77
Iridium

Its name is taken from the Latin, iris, "rainbow."

Element 78
Platinum

Platinum is commonly classified as a precious metal, belonging to a distinctive group of metals that also includes gold (Au), silver (Ag), iridium (Ir) and palladium (Pd). There are metals on the periodic table of elements that are far more rare than any of these; but scarcity is not the sole measuring stick of value. Tradition and commercial demand combine with availability to define a precious metal.

Element 79
Gold

Gold is a relatively rare element in the earth's crust. On the average, a million tons of earth contains just ten pounds of pure gold. Fortunately, gold is not evenly distributed through the earth's crust; rather, it is found in a few fairly rich deposits. It is estimated that there is enough gold in the world to make a cube of the metal that measured 60 feet on a side.

Element 80
Mercury

You can appreciate the enduring nature of mercury's commercial products by considering that one of the world's best-known mercury mines (the Almadn mine in Spain) has been in continuous operation since 400 BC!

Element 81
Thallium

Thallium was discovered accidentally by Sir William Crookes (1832-1919) in 1861. It was a purely serendipitous discovery--no one suspected its existence, so no one was looking for it. As far as Sir William was concerned, his contribution to the table of elements was simply a matter of doing the right thing with the right equipment at the right time.

Element 82
Lead

The alchemists--those who lived in a strange world between science and fantasy-- believed every element eventually changes, or transmutes, into lead. (And if a little gold happened turned up in the mixture somewhere along the way, so much the better.)

Element 84
Polonium

It is named for Poland, Mme. Curie's native country.

Element 85
Astatine

All the isotopes of astatine are radioactive and have short half-lives. It is believed that traces of astatine-215, -218 and -219 might exist naturally in the earth's crust; but if they do, the total amount weighs less than an ounce.

Element 86
Radon

Radioactive gas! It sounds like something from a B-grade science-fiction movie of the 1930s and '40s. It really exists, though, as the element radon. It was discovered by accident during the first year of the 20th century, and it is now regarded as a potential health hazard in the air of basements in countless American homes.

Element 87
Francium

The scientific literature of the era shows people giving element 87 names such as russium, virginium and moldavium. None of these claims of discovery passed the final tests ... until 1939. Marguerite Catherine Perey (1909-1975) was a an assistant to the most successful and respected female scientist, Marie Curie at the Radium Institute in Paris. Perey continued her work after Marie Curie died in 1934, unravelling the sequence of events we now know as the actinium radioactive decay series.

Element 88
Radium

Radium is an active metal. It not only glows in the dark with an eerie bluish light, but also combines violently with water to produce the hydroxide. And it is intensely radioactive. The handwritten laboratory notes of the discoverers, M. and Mme. Curie, are still too radioactive today for safe handling.

Element 89
Actinium

Actinium is a rare, extremely radioactive metal that glows in the dark with an eerie blue light. It was discovered twice, first by Andr-Louis Debierne in 1899, then again by Friedrich Otto Giesel in 1902. Giesel chose to name the new element emanium. Unfortunately, Debierne's paperwork was running a couple years ahead of Giesel's, so Debiern's chosen name, actinium, took priority.

Element 90
Thorium

The discovery of thorium begins with a curious mineral found by a skilled and enthusiastic amateur mineralologist, one Reverend Has Morten Thrane Esmark (1801-1882).

Element 91
Protactinium

Incidentally, the scarcity of protactinium supports the observation that heavy elements having odd atomic numbers are far more rare than those having even atomic numbers. Ninety-one is an odd number, and protactinium is indeed a rare element.

Element 92
Uranium

Uranium is no longer considered a rare element. The proportion of uranium is now reckoned to be 2 parts-per- million, making it more common in the earth's crust than tungsten, molybdenum and beryllium.

Element 94
Plutonium

The element plutonium is a key player in the roller-coaster history of the Atomic Age. In the earliest years, it was an important ingredient in the development and production of the first atomic bombs. And, in later years, it became known as an environmentally hazardous radioactive waste from nuclear power plants, thus playing an important role in dimming the future of domestic atomic energy.

Element 95
Americium

What was so simple at the initial discovery stage turned out to be a long and tedious procedure through the necessary identification stages. For a time, at least one of the workers suggested appropriate names for the two new element, "pandemonium" and "delirium." The name americium was chosen for element 95 because it turned out to be similar to the rare earth element, europium. And since the rare-earth analogue was named according to its continent of discovery, Europe, the new element should be likewise named.

Element 96
Curium

The Berkeley cyclotron had barely cooled down after Glenn T. Seaborg and his co-workers announced their discovery of plutonium (element 94) when they put it to work in search of elements 95 and 96.

Element 97
Berkelium

The fourth new element in a decade was ready by 1950, and it was about time someone thought about naming an element in honor of the Berkeley laboratory and the city of the same name.

Element 98
Californium

The problem with naming element 98 was that the origin of the name of its rare-earth analogue, Dysprosium (element 66) has no special significance. It wasn't named after a specific person, place or thing. Dysprosium literally means "hard to get at." The Berkeley group decided to ignore precedence altogether in this instance and name element 98 after the state of California. (Someone later suggested that californium was indeed an appropriate name because America's ninteenth-century settlers found California "hard to get at.")

Element 99
Einsteinium

Naturally it is not feasible to blow up an island every time you want a new sample of einsteinium; so researchers worked out a somewhat more time-consuming, but less calamitous, alternative.

Element 100
Fermium

Albert Ghiorso and his co-workers at the Berkeley (University of California) detected fermium in the residue of the first thermonuclear, or hydrogen bomb, explosion in November, 1952 ... and so did researchers at the Argonne Laboratories in Idaho. There was a need to straighten out the priority of discovery in order to give the earlier discoverer the proper recognition, including the right to name the element. The only problem was that a veil of secrecy surrounding the first thermonuclear explosions made it impossible for the groups to publish their results and thereby fix the official dates of their findings.

Element 101
Mendelevium

Named in honor of Dmitri Mendeleyev.

Element 102
Nobelium

The Berkeley group could not reproduce the findings of the Nobel group, however. Furthermore, a Russian team at Dubna could reproduce the Berkeley results, but not the Nobel results. So the highly respected International Union of Pure and Applied Chemistry finally found itself with some egg on its face--it has been too hasty in accepting the claim of the group from the Nobel Institute.

Element 104
Unnilquadium

Not only did the American group produce a wider variety of isotopes of element 104, but it produced larger quantities--thousands of atoms of each, instead of the Soviet's two or three. The Soviet group is thus challenged to produce more convincing evidence than they have done thus far.

Element 105
Hahnium

There is no longer any question that the element has been found; the only problem is one of placing the priority of discovery.

Element 106
Unnilhexium

The Soviet Joint Institute for Nuclear Research announced their disovery of element 106 in June, 1974. Three months later, the U.S. group at Berkeley claimed positive discovery of the same element. The claims have not been fully evaluated to establish priority, so the element is sitting in limbo for the time being.

Element 107
Unnilseptium

Soviet scientists reported they had produced an isotope of element 107 in 1976. Their claim has since been substantiated by German researchers. But for reasons that are difficult to understand, the Soviets were slow to suggest names for their elements--even where there seems to be positive evidence of priority of discovery.