My Science School

In the year 1898, Marie and Pierre Curie made their first elemental discovery and that was polonium. They discovered polonium and then radium in the same year in Paris while studying the radioactivity in pitchblende (uranium oxide). Polonium is named after Poland, where Marie Curie was born and raised.

The Curies were not aware of the dangers of working with radioactive elements when they made their discoveries. Polonium is harmful because of its chemical toxicity and radioactivity. Exposure to polonium puts people at the risk of getting various cancers.

Radium was discovered in 1898 by the Curies. To extract 1 gram of radium, about eight tons of pitchblende which has up to 50 percent uranium is needed. The element radium gets its name from the Latin word ‘radius’ which means ray. This is based on the rays emitted by this radioactive element. Metallic radium was first isolated by Marie Curie and Andre Debierne in 1910 by the electrolysis of pure radium chloride solution.

Radium is highly radioactive and causes cancer.

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Sir William Crookes discovered Thallium in 1861 in London. In 1850, Crookes received a deposit from a sulphuric acid factory in Tilkerode, Germany which contained selenium. He extracted the selenium, but he was left with residues that seemed to contain tellurium in it. Eleven years later, when Crookes needed some tellurium, he tried to do the experiment again.

However, this time, he was unable to isolate any tellurium. Wondering what happened, he decided to analyze the residues using a spectroscope and noticed a bright green line in the spectrum, which did not match with any known element. After many experiments, Crookes concluded that the line was due to a new element. He announced his discovery in March 1861.

Claude-Auguste Lamy had independently discovered and isolated pure thallium in 1862 in France.

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Bismuth had been known as early as 1400, but it was often confused with lead due to their similar properties. French chemist Claude Geoffroy the Younger, in 1753, was the first to prove that bismuth was a separate element and not lead. The word “bismuth” is the Latinized form of the Old German word “weissmuth”, which means “white substance”. It is possible that this name evolved due to the element’s white oxide.

This element is used in medicine, in cosmetic products, in low-melting alloys, fire detection/extinguishing systems, and as a replacement for lead in shot and bullets (bismuth-tin alloy).

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In 1779 Peter Woulfe, an Irish chemist, claimed the existence of a new element tungsten. He declared it from his analysis of the mineral wolframite (an iron manganese tungstate mineral). At that time, there was no suitable furnace to reduce the oxide, so pure tungsten was not obtained.

Tungsten was finally isolated by Fausto and Juan Jose de Elhuyar in 1783. They were two brothers based in Spain. They obtained tungsten by reducing acidified wolframite with charcoal. Its chemical symbol, W, comes from the original name of the element, that is, Wolfram. Tungsten is one among the five major refractory metals, which have very high resistance to heat and damage.

This element is one of the toughest materials found in nature. It is highly dense and almost impossible to melt.

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Osmium was discovered by English chemist Smithson Tennant in London in the year 1803. His discovery of osmium took shape when he dissolved a sample of crude platinum in aqua regia, a mixture of hydrochloric acid and nitric acid. The process resulted in a metallic, black powder.

Older chemists were of the opinion that this powder was graphite, but Tennant thought differently. He treated the powder with sodium hydroxide and heated the solution. He then removed an alkali from the residue by mixing it with water. Tennant then added hydrochloric acid to the remaining residue to form an acidic solution. He observed that the alkaline solution contained osmium, whereas the acidic solution contained iridium. Osmium tetroxide, OsO4, which was formed in this reaction was highly toxic and had a bad odour. Because of this, Tennant named the element after the Greek word for smell, osme.

Osmium-platinum alloys are used in the manufacturing of pacemaker electrodes as they are highly resistant to corrosion.

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Platinum was first used by people in South America, who produced artefacts of a white gold-platinum alloy. The first written document that speaks of platinum was written by Julius C Scaliger in 1557.

But he was proved wrong by Francois Chabaneaus, a French chemist, in 1783. Chabaneaus discovered and patented a method of producing workable platinum, though the quality of the metal was still very inconsistent.

Later, in the early 19th century, an English chemist named William H Wollaston developed a commercial process for producing pure platinum. The element gets its name from the Spanish word platina, which means ‘little silver’.

Platinum is highly valued and desired. It has a wide range of uses, which includes making jewellery, catalytic converters, electrical contacts, pacemakers, medication, and magnets. It is a rare metal and makes up only about 5 parts per billion by weight of the Earth’s crust. This scarcity makes it very costly.

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Ytterbium was discovered in the year 1878 by Jean Charles Galissard de Marignac in Geneva, Switzerland. To obtain it, he heated erbium nitrate until it was decomposed, and then he extracted the residue, which contained an unknown white powder. He named it ytterbium oxide (ytterbia).

In 1907, in Paris, George Urbain separated ytterbia into two constituents-two rare earth oxides. One is ytterbium, the other is called lutetium. Ytterbium metal was first made in 1937.

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The presence of hafnium was originally predicted by Dmitri Mendeleev in 1869. In 1921, Neils Bohr asked Georg von Hevesy, a Hungarian chemist, to look for the missing element in zirconium ores. Hevesy and Dirk Coster, a Dutch physicist, discovered hafnium in 1923 using x-ray spectroscopy while they analyzed the zirconium ores. Later, in 1925, Anton Eduard van Arkel and Jan Hendrik de Boer discovered a method for producing high purity hafnium.

The process of isolating hafnium included the decomposition of hafnium tetraiodide (HfI4) on a white-hot tungsten filament. It is known as the crystal bar process as it creates a crystal bar of pure hafnium.

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Jean Charles Galissard de Marignac, a Swiss chemist, was the first to record the existence of gadolinium, atomic number 64, in 1880. He recorded unknown spectroscopic lines in an oxide preparation taken from the mineral samarskite.

In 1886, Paul Emile Lecoq de Boisbaudran, a French chemist, confirmed Marignac’s discovery and suggested the name gadolinium for the new element. This element was named after the 18th century chemist and mineralogist Johan Gadolin and was accepted by Marignac. 99.3 percent pure gadolinium was first prepared by Felix Trombe, a French chemist in 1935.

Gadolinium is obtained from the mineral gadolinite. It is also found in several other minerals such as monazite and bastnasite that have commercial implications.

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The elements erbium and terbium were discovered by Carl Gustaf Mosander, a Swedish chemist, in 1843. He had discovered lanthanum four years earlier. His former supervisor, Jacob Berzelius, had discovered the new element cerium in cerite, so Mosander continued to study cerite and discovered lanthanum. Later, in 1843, he began studying the mineral gadolinite. Johan Gadolin had discovered yttrium from gadolinite in 1794.

Mosander began studying gadolinite in the hope of finding another element. He made studies on a sample of yttria (that is, yttrium oxide) obtained from this mineral, and found that it actually contained two other, previously unknown, metal oxides. He called them erbia and terbia. They contained the two new rare earth metals called erbium and terbium. What is interesting is that Mosander had now discovered three new elements, (lanthanum, erbium, and terbium) all rare earths, in minerals that other scientists had discarded after making their discoveries.

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Dysprosium, atomic number 66, was discovered in 1886. French chemist Paul Emile Lecoq de Boisbaudran found the element when he separated dysprosium oxide from holmium oxide. Boisbaudran had also discovered gallium in 1875. He was also the first person to isolate samarium in 1879 using fractional separation.

Boisbaudran devised a very complicated and time-consuming procedure for the separation of dysprosium. The process had 32 precipitations of the hydroxide using ammonia, which was followed by 26 precipitations of the insoluble oxalate salt.

In this context, he named this new element dysprosium, which means ‘hard to obtain’ in Greek. The element lived up to its name for another eighty years until pure metallic dysprosium was isolated using ion-exchange chromatography in the 1950s.

One of the most important uses of dysprosium is in the manufacturing of data storage devices such as compact discs and hard discs. It is also used in medium source rare-earth lamps (MSRs), which produce an intense white light in the film industry.

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Eugene-Anatole Demarcay discovered europium by using a new spectroscope, which he developed to study rare earth elements. His spectroscope had an induction coil that could produce a very high spark temperature and used platinum electrodes to remove all other spectral lines. His spectral results were not approved by many and he made it a point to find more proof. He got his proof in 1901, when he was able to isolate europium through repeated crystallization of samarium magnesium nitrate and earned the title of being its discoverer. What is striking is, had samarium not been found, Demarcay would not have found europium. The element gets its name from the continent of Europe.

In 1904, French chemist Georges Urbain separated europium from impure gadolinium using bismuth magnesium nitrate. He discovered that bismuth nitrate will crystallise between two fractions of rare earth in most conditions, which makes it easy to separate them.

Europium is used as control rods in nuclear reactors because of their effectiveness in absorbing neutrons. Europium oxide is also used as a phosphor activator. Europium doped plastics are used as laser materials and for producing superconducting alloys. It also helps in anti-forgery measures of the euro currency.

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Czech chemist Bohuslav Brauner first predicted the existence of an element between neodymium (No.60) and samarium (No. 62) in 1902. Later in 1926, American chemist B. Smith Hopkins at the University of Illinois claimed that the element was found in rare-earth residues of monazite and he named it illinium, a name derived from the name of his university and State.

Italian chemist Luigi Rolla at the Royal University in Florence also claimed to have discovered the element in 1924 and he named it florentium (his work was not published until 1926). Finally, in 1945, strong evidence that element 61 had been isolated was formulated by Jacob. A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell at Oak Ridge, Tennessee.  They created it from fission products of uranium.

The element was named promethium, and it was accepted in 1949 by the International Union of Pure and Applied Chemistry. The name was derived from the Greek Titan Prometheus, who stole fire from Mount Olympus to give it to mankind according to mythology.

Promethium is mostly used for research purposes. Another commercial use for promethium is that it is a power source for medical devices. Promethium is also useful as   a beta source for thickness gauges.

Promethium is often produced as a product of uranium fission.

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Praseodymium was first identified in 1885 in Vienna by Carl Auer von Welsbach, an Austrian Scientist. It was discovered in ‘didymium’, a substance that was incorrectly identified by Carl Mosander to be a new element in 1841. What is interesting is that this non-existent element ‘didymium’ was given a place and the symbol Di in Mendeleev’s first periodic table in 1869.

Later, in 1879 a French chemist, Lecoq de Boisbaudran identified and separated samarium from what was called ‘didymium’. Once samarium was discovered, it was observed that the absorption spectrum of ‘didymium’ gave different results depending on the mineral from which it had been sourced.

In 1882, Bohuslav Brauner from Prague published a paper on the atomic weight determinations for rare earth elements. But in his data, ‘didymium’ had variable atomic weights. This convinced Brauner that ‘didymium’ was a mixture of elements. Though he attempted to separate them, he was not successful.

Later in 1885, Carl Welsbach, who had originally discovered ‘didymium’, realized it was a mixture of two new elements and named them praseodymium and neodymium.

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Cerium was discovered by Jacob Berzelius and Wilhelm von Hisinger in Sweden, and independently in the same year by Martin Klaproth in Germany. Atomic number 58, its discovery dates back to 1803.

Berzelius and Hisinger discovered cerium from a rare reddish-brown mineral known as cerite. The scientist duo prepared cerium salts from cerite and investigated its chemical reactions. They were not successful in isolating the pure metal, but they found that cerium had two oxidation states. They discovered that one state yields colourless salts and the other yields yellow-red ones. They named the new element cerium after the asteroid Ceres.

Klaproth also analyzed the mineral, and indicated that it contains the oxide of a new element, which he named ockroite. But Berzelius and Hisinger had published their results before Klaproth, and the name cerium was accepted rather than ockroite.

India and Brazil have large deposits of cerium. It is a component of mischmetal, which is used in the manufacture of alloys for cigarette lighters. Cerium oxide is used in incandescent gas mantles as a glass polishing agent.

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