My Science School

Atomic number 54, xenon, was discovered by William Ramsay and Morris Travers at the University College, London. The duo had already discovered argon, neon, and krypton from liquid air. In 1898, Ludwig Mond a wealthy industrialist gifted the team a new liquid-air machine which led to this discovery. With the new machine, Ramsay and Travers extracted more krypton from liquid air, and they distilled it to isolate a heavier gas. Ramsay and Travers examined this heavier gas in a vacuum tube and found that this element emitted a beautiful blue glow. The duo categorized this new gas as inert and called it xenon. “Xenos” in Greek means stranger.

Xenon in itself is not toxic but many of its compounds are toxic in nature. It is used in photographic flashes, in high pressure arc lamps for motion picture projection, and to produce ultraviolet light.

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Vincentius Casciorolus was a shoemaker, who had great interest in alchemy. In the early 1600s, he learned about a heavy, silvery-white mineral with remarkable properties in the mountains near Bologna, Italy. He was very excited at the news and thought that it was the ‘Philosopher’s Stone’, which alchemists thought could be the substance that could make gold.

When this mineral was heated and combusted, its product gave out a phosphorescent red glow. In addition, if sunlight was introduced to the combusted material, it would glow in the dark for an hour afterwards. Now we know that this mineral, which excited Casciorolus and many others, was baryte, BaSO4.

Though the discovery was a profound moment in science, it was quite useless for the discoverers who were trying to make gold from other metals. This stone, rather than being the ‘Philosopher’s Stone’, became the ‘Bologna Stone’.

About 170 years later, Carl Scheele, a scientist in Sweden, discovered a new earth metal. Because it was very heavy, he called it terra ponderosa, which means ‘heavy earth’ in Latin. Additional research showed that this heavy metal was the same as the Bologna stones.

A little more than 25 years after that, Sir Humphrey Davy was finally able to figure out how to obtain a pure sample of this mineral, which he called barium (BAR-ee-um), based on the Greek Word barys, which means ‘heavy’. The Bologna stones were found to be baryte, which is a combination of the elements barium, sulfur, and oxygen.

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German chemist Friedrich Stromeyer discovered cadmium (atomic number 48) in 1817. It was discovered as an impurity in zinc oxide. Stromeyer was also an inspector of apothecaries, and in this capacity, he inspected various pharmacies. Zinc oxides were used to treat skin diseases during that time but many pharmacies used zinc carbonate instead of zinc oxide.

Stromeyer began heating these samples of zinc carbonate in his laboratory and observed that they were becoming discolored at high temperatures. Knowing that pure zinc carbonate does not discolor, Stromeyer reasoned that some impurity must have caused the reaction. He created an experimental procedure to identify the impurity and was able to isolate cadmium, a silver-blue metal.

Cadmium was also discovered by German Chemist Karl Hermann in 1818 independently.

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Atomic number 49, indium was discovered by Ferdinand Reich in 1863 in Germany. His intention was to examine whether zinc sulphide ore (sphalerite) contained thallium. But his research led to the discovery of a new element after his detailed observations. He roasted the ore to remove most of the sulphur and decomposed the remaining with hydrochloric acid. A straw- coloured solid appeared which he suspected to be the sulphide of a new element. He further studied it by getting an emission spectrum for the sample. But unfortunately, he was colour blind and was not able to accurately analyze this. He asked for help from a fellow German chemist named Hieronymus T Richter, who found an indigo line. This line was a new one and did not match any known element.

This information helped them to understand that a new element was present in the sample. Thus they discovered indium.

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Tellurium, atomic number 52, was discovered in the year 1782 by Muller von Reichenstein. But it got its name only in 1798 when German chemist Martin Heinrich Klaproth officially called it ‘tellurium’. We have discovered thirty isotopes of tellurium although natural tellurium has only eight isotopes. The element and its compounds are considered toxic for humans.

This element is usually found as calaverite, which is the telluride of gold. It is found combined with other metals as well. Occasionally, tellurium is also found in its natural state. One can obtain amorphous tellurium by precipitating it from a solution of telluric acid.

Tellurium is a semiconductor. It is also used to improve the properties of copper and stainless steel. When tellurium is added to lead, it improves the strength and hardness of the metal. It also decreases the corrosion in lead.

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Iodine was discovered by accident during the Napoleonic Wars by Bernard Courtois, a French chemist, in 1811. He was helping his father to manufacture saltpetre, which is an important component in gunpowder. This compound was in heavy demand at the time. Initially, he had been using wood ash as the source of potassium nitrate that was needed to make saltpetre. But due to the shortage in wood ash, Courtois began using seaweed in its place. To isolate the sodium and potassium extracts from the seaweed, he used to burn the seaweed and wash its ash with water. Later, sulfuric acid was added and the leftover waste was removed. But once when Courtois added a little too much sulfuric acid, he noticed a cloud of violet gas. With further analysis, he discovered that this vapour would form deep violet crystals on cold surfaces when condensed.

At that time, Courtois knew that he had discovered a new element, but he did not know that it was iodine. He shared some samples with other scientists to continue the research. These scientists later confirmed that it was a new element.

Although Courtois did not name the element, he was later acknowledged as the first person to isolate iodine. He received the Montyon Prize from the Royal Academy of Sciences in 1831 for his work.

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William H. Wollaston discovered Palladium in 1803. He experimented on the residues left after dissolving platinum in aqua regia. He successfully isolated palladium by heating palladium cyanide to produce palladium metal. But Wollaston decided to announce his discovery in an unconventional manner. He gave a quantity of the metal for sale to a mineral dealer in London, and posted handbills describing the property of the new metal, anonymously.

Many doubts came up with this peculiar way of announcement, and Richard Chenevix, a renowned chemist of the time stated that palladium was just an alloy of platinum and mercury. In response to that, Wollaston announced a reward of twenty guineas to anyone who could produce the metal artificially. Nobody claimed the money. In 1805, Wollaston made a speech before the Royal Society of London about the properties of palladium and how to isolate it. He revealed he was the discoverer of the metal at the end of the speech. He explained that he remained anonymous to use the time to study and reveal more properties of the metal.

Palladium is named after an asteroid called ‘Pallas’, which refers to the Greek goddess of wisdom.

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English chemist William H. Wollaston discovered rhodium in 1803 while he was experimenting on a platinum ore in Peru. Hippolyte- Victor Collet- Descotils alerted Wollaston about the chance of a new element as he believed that the red colour of some platinum salts was due to the presence of an unidentified metal.

To find out this new metal, Wollaston, dissolved crude platinum in aqua regia, which is a concentrated solution of hydrochloric and nitric acids. After that he precipitated platinum by dissolving the solution in ammonium chloride. But there was no new element.

Further experiments produced a deep red powder, sodium rhodium chloride. When this compound was treated with zinc, it gave a black and flaky precipitate of rhodium. Wollaston named the element rhodium based on the Greek word ‘rhodon’, which means rose.

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Technetium is the first artificially produced element. Dmitri Mendeleev, the Russian chemist who created the periodic table, is the first person to predict the existence of technetium, atomic number 43. But he called it eka-manganese. Three scientists: lda Take, Walter Noddack, and Otto Berg examined some platinum ores and columbite minerals in hopes of discovering eka-manganese and rhenium, atomic number 75.

They published the X-ray analysis of their experiment and claimed that they found 2 new elements. Element 43 was named as masurium by them. But their findings were disregarded by the scientific community then. After three years, their finding of rhenium, element 75, was approved but masurium was not.

Carlo Perrier and Emilio Segre were credited with the discovery of technetium at the University of Palermo in Italy in 1937.

It is the first element that was created synthetically. Technetium was derived from the Greek word ‘technetos’, which means artificial. Technetium is a silver grey metal that is rare. It gets damaged slowly in moist air.

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The mineral molybdenite (molybdenum sulphide) was often mistaken for graphite or lead ore until 1778. This soft black mineral was analyzed by German chemist Carl Scheele, who discovered that it was neither of these substances, and that it was a totally new element. But Scheele did not have a suitable furnace to reduce the mineral to a metal. As a result, it took a few more years until it was actually identified. Although Scheele made a number of chemical discoveries such as oxygen, the credit was always given to someone else because he couldn’t come to a final analysis. As a result, he later became known as “hard luck Scheele”.

For many years, scientists continued to assume that molybdenite had a new element, but they could not reduce the mineral to the metal and isolate it. Later, Peter Jacob Hjelm, a Swedish chemist, ground molybdic acid with carbon in linseed oil to form a paste. Then he allowed this paste to be in close contact with carbon and the molybdenite. This mixture was then heated in a closed crucible to produce the metal. He named it molybdenum (atomic number 42) after the Greek word “molybdos”, which means lead. According to the Royal Society of Chemistry, this new element was announced in the autumn of 1781.

Molybdenum has silvery-white appearance and it is ductile and highly resistant to corrosion. It also has one of the highest melting points of all pure elements. Only tantalum and tungsten have higher melting points than molybdenum. This element is also a micronutrient that is essential for life.

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Niobium, atomic number 41, was discovered by Charles Hatchett, an English scientist in 1801. It was recognised in an ore sent to England from the American colonies, more than a century earlier by John Winthrop the Younger, who was the first governor of the state of Connecticut. The ore was called columbite and Hatchett named this element columbium (symbol Cb).

Later, in 1846, a German chemist named Henrich Rose independently discovered the element and named it niobium. This metal was first isolated by Christian Blomstrand, a Swedish scientist, in 1864.

Internationally, the name niobium was adopted in 1950. Niobium is a shiny, white, ductile metal. Due to its many properties, niobium is used in many areas of research and in creating magnets. One of the strongest superconducting magnets in the world makes use of niobium alloy wires such as niobium-tin and niobium-titanium.

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The discovery of yttrium (atomic number 39) began in 1787 when Carl Arrhenius found a mineral that resembled coal in a quartz mine near Ytterby of Sweden. Arrhenius named this black mineral ‘ytterbite’ based on Ytterby, where it was found.

In Finland, Johan Gadolin received a sample of ytterbite from Arrhenius. He carried out a detailed analysis of it in 1794 and found that it contained an unknown earth metal. The new metal was named yttrium. His results were confirmed by Anders Ekeberg, a Swedish chemist in 1797.

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Strontium, atomic number 38, was recognized as a new element in 1790. A mineral sample from a lead mine near Strontian in Scotland (after which the element is named) was analysed by Adair Crawford, leading to this discovery. Until then, the scientific community thought that strontium and barium were the same element. Scientists had only discovered barium’s existence by then. It was initially called strontianite (strontium carbonate). Strontium was first isolated by Sir Humphry Davy in 1808 while working in London. He used electrolysis to isolate it.

Strontium is very common in nature and is the 15th most abundant element in the planet’s crust. Physically, strontium is a soft, silvery metal. It is used to block X-rays emitted by TV picture tubes. It causes paint to glow in the dark and is responsible for the bright red colours in fireworks. Strontium is also vital in understanding the origin of the species as anthropologists study the levels of strontium ions in fossils to determine the geographic origins of ancient humans and animals. The compound strontium chloride is used in toothpaste to help people with sensitive teeth. Strontium oxide also improves the quality of pottery glazes.

Natural strontium is harmless, but one of its isotopes, Sr-90, is a very dangerous by-product of nuclear fallout. The world’s most accurate atomic clock is based on strontium atoms.

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Rubidium, atomic number 37, was discovered in 1861. It was discovered in Heidelberg in Germany by Robert Bunsen and Gustav Kirchhoff using spectroscopy. This method was invented and developed by the pair in the previous two years. At the heart of the spectroscope there is a glass prism, which splits the light coming from a flame into a spectrum. This is very similar to how raindrops can split sunlight into a rainbow.

When different salts were placed in the flame of the recently invented Bunsen burner, Bunsen and Kirchhoff saw coloured lines in all the spectra they saw. What was more exciting was that they discovered that these coloured lines were unique to the substance that was burnt. They concluded that the lines in a spectrum were a way of finger-printing an element.

In 1861, the duo began studying the mineral lepidolite (a lithium, potassium and aluminium silicate). This mineral was found in Saxony, Germany. Bunsen and Kirchoff used hydrochloroplatanic acid to isolate potassium chloroplatinate from the mineral. In potassium chloroplatinate that was isolated, they found another salt. This salt produced a spectrum containing many new lines when it was placed in the Bunsen burner. Two of the lines that were produced were particularly outstanding. It was a new element. They named this new element rubidium (and the symbol Rb) from the Latin word rubidius, which refers to the darkest red colour.

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In 1825, a salt maker sent a sample of salt spring waters from Bad Kreuznach, a German town, asking chemist Justus von Liebig for an analysis. This sample had a very high amount of bromine in it, and Liebig had isolated it too. But he considered the substance as a compound of iodine and chlorine. Had he not taken it lightly, Liebig would have been the discoverer of bromine.

The next person in the story of bromine’s discovery is Carl Loewig, who discovered it while he was still a chemistry student at Heidelberg University in Germany. Loewig’s hometown was Bad Kreuznach, the same place from where Liebig had received the sample. Loewig took water from a salt spring in his hometown and added chlorine to it. He then shook the solution with ether and found that a red-brown substance dissolved in the ether. Loewig evaporated the ether to find bromine, a red-brown liquid.

Loewig’s professor at Heidelberg University asked him to prepare more of this substance for testing. But this took him a year, and by that time, in 1826, another person named Antoine Balard had discovered bromine and took the credit. Balard took brine (evaporated sea water in which salts have been concentrated) and crystallized salt from it. After that, he took the remaining liquid and mixed it with chlorine. Later, this solution was distilled, which left behind a dark red liquid-bromine.

Balard published his results in 1826, which provided evidence to the discovery. Since he was the first to publish, he came to be known as bromine’s discoverer.

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