Discovery of Titanium
Titanium’s discovery was announced in 1791 by the amateur geologist Reverend William Gregor from Cornwall, England.
Gregor found a black, magnetic sand that looked like gunpowder in a stream in the parish of Mannacan in Cornwall, England. (We now call this sand ilmenite; it is a mixture consisting mainly of the oxides of iron and titanium.)
Gregor analyzed the sand, finding it was largely magnetite (Fe3O4) and the rather impure oxide of a new metal, which he described as ‘reddish brown calx.’
This calx turned yellow when dissolved in sulfuric acid and purple when reduced with iron, tin or zinc. Gregor concluded that he was dealing with a new metal, which he named manaccanite in honor of the parish of Mannacan.
Having discovered a new metal, Gregor returned to his pastoral duties.
Little more happens in our story until 1795, when the well-known German chemist Martin Klaproth experienced the thrill of discovering a new metallic element. Klaproth called the new metal titanium, after the Titans, the sons of the Earth goddess in Greek mythology.
Klaproth discovered titanium in the mineral rutile, from Boinik, Hungary. Just like Gregor’s calx, the rutile was a red color. In 1797 Klaproth read Gregor’s account from 1791 and realized that the red oxide in which he had found titanium and the red oxide in which Gregor had found manaccanite were in fact the same; titanium and maccanite were the same element and Gregor was the element’s true discoverer.
Gregor may have beaten Klaproth to the new metal, but scientists preferred Klaproth’s ‘titanium’ to Gregor’s ‘manaccanite.’
Obtaining a sample of pure titanium proved to be much harder than discovering it.
Many scientists tried, but it took 119 years from its discovery until 99.9% pure titanium was isolated in 1910 by metallurgist Matthew Hunter in Schenectady, New York, who heated titanium (IV) chloride with sodium to red-heat in a pressure cylinder.
In 1936, the Kroll Process (heating titanium (IV) chloride with magnesium) made the commercial production of titanium possible. By 1948 worldwide production had reached just 3 tons a year.
By 1956, however, scientists and engineers had realized titanium’s properties were highly desirable and worldwide production had exploded to 25,000 tons a year.
The 2011 forecast for worldwide production of titanium metal using the Kroll process was 223,000 metric tons.
Discovery of Magnesium
Magnesium and calcium were once thought to be the same substance. In 1755 Scottish chemist Joseph Black showed by experiment that the two were different. Black wrote:
“We have already shewn by experiment, that magnesia alba [magnesium carbonate] is a compound of a peculiar earth and fixed air.”
Magnesium was first isolated by Sir Humphrey Davy in 1808, in London, England. Davy had built a large battery and used it to pass electricity through salts. In doing so, he discovered or isolated for the first time several alkali and alkali earth metals.
In magnesium’s case, Davy’s method was similar to the one he used for barium, calcium and strontium.
Davy made a paste of moist magnesium oxide and red mercury oxide. )
He made a depression in the paste and placed about 3.5 grams of mercury metal there to act as the negative electrode. He used platinum as the positive electrode. Davy did the experiment under naphtha (a liquid hydrocarbon under which he had found he could safely store potassium and sodium).
When electricity was passed through the paste, a magnesium-mercury amalgam formed at the mercury electrode. (In later experiments Davy used moist magnesium sulfate instead of the oxide and obtained the amalgam much faster.)
The mercury was then removed from the amalgam by heating to leave magnesium metal.
In a lecture to the Royal Society in June 1808, Davy described how the magnesium he obtained was not pure because of difficulties in removing the mercury entirely from the magnesium. He was, however, able to observe that in air the metal turned into a white powder, gaining weight as it reacted with oxygen and returned to its oxide form.
Davy thought the logical name for the new metal was ‘magnesium’ but instead called it ‘magnium.’
He thought the name ‘magnium’ was, “objectionable, but magnesium has been already applied to metallic manganese…”
By 1812, Davy had changed his mind, following the “candid criticisms of some philosophical friends,” and the new metal became known as magnesium, while metallic manganese became known as… manganese.
Magnesium’s name is derived from magnesia, which Davy used in his experiment. Magnesia is the district of Thessaly in Greece where magnesia alba [magnesium carbonate] was found.
In France, in 1830, Antoine Bussy published his work showing how pure magnesium metal could be obtained. Bussy had read Friedrich Wöhler’s 1828 publication of how he had produced pure aluminum by reacting aluminum chloride with potassium. By analogy, Bussy thought he could do something similar to produce pure magnesium from magnesium chloride; he was correct.
Under red heat he reacted magnesium chloride with potassium vapor and obtained pure magnesium. He wrote, “The metal is silvery white, very brilliant, very malleable, flattens into flakes under a hammer… dilute acids attack the metal, releasing hydrogen.”
Discovery of Calcium
People have used calcium’s compounds for thousands of years – in cement, for example.
Limestone [calcium carbonate] was called calx by the Romans. The Romans heated calx, driving off carbon dioxide to leave calcium oxide. To make cement, all you have to do is mix calcium oxide with water. The Romans built vast amphitheaters and aqueducts using calcium oxide cement to bond stones together.
Despite the long history of calcium’s compounds, the element itself was not discovered until electricity was available for use in experiments.
Calcium was first isolated by Sir Humphry Davy in 1808 in London. In a lecture to the Royal Society in June 1808, Davy described his experiments that year, which produced tiny amounts of metal, at best. He could not find any way to produce more calcium metal until a letter from Jöns Berzelius in Stockholm pointed him in the right direction.
Davy learned that Berzelius and Magnus Pontin had used a battery to decompose calcium oxide at a mercury electrode and they had obtained an amalgam of mercury and calcium. (Berzelius, the great Swedish chemist, exchanged a great deal of information with Davy. Berzelius had earlier learned from Davy that potassium could be dissolved in mercury to form an amalgam. Berzelius had extended the method.)
Davy made a paste of slaked lime [calcium oxide, slightly moistened to form calcium hydroxide] and red oxide ofmercury [mercury (II) oxide].
He made a depression in the paste and placed about 3.5 grams of mercury metal there to act as an electrode. Platinum was used as the counter electrode. Davy carried out the experiment under naptha (a liquid hydrocarbon under which he had found he could safely store potassium and sodium).
When electricity was passed through the paste, a calcium-mercury amalgam formed at the mercury electrode.
Davy removed the mercury by distillation to reveal a new element: calcium.
Davy used the same procedure to isolate strontium,barium, and magnesium.
He named the metal calcium because of its occurrence in calx.
Discovery of Potassium
In 1806 English chemist Sir Humphry Davy discovered that chemical bonding was electrical in nature and that he could use electricity to split substances into their basic building blocks – the chemical elements.
In 1807 he isolated potassium for the first time at the Royal Institution, London. He electrolyzed dried potassium hydroxide (potash) which he had very slightly moistened by exposing it to the moist air in his laboratory. The electrolysis was powered by the combined output of three large batteries he had built.
When he applied a voltage from his batteries to the potassium hydroxide, he found globules “having a high metallic lustre” collected at the negatively charged electrode.
Edmund Davy, who assisted in the experiment, described Sir Humphry Davy’s reaction to the production of potassium metal, his Eureka moment:
“… when the minute globules of potassium burst through the crust of potash, and take fire as they entered the atmosphere, he could not contain his joy – he actually danced about the room in ecstatic delight; some little time was required for him to compose himself sufficiently to continue the experiment.”
Potassium was the first metal to be isolated by electrolysis.
Davy was astonished at the new metal’s low density, observing that it floated on oil – something no other metal would do. He placed a piece of potassium in water and observed that the water, “decomposes it with great violence, an instantaneous explosion with brilliant flame. He also (bravely) added potassium to hydrochloric acid and saw it burn with a bright red flame.
The name potassium is from the English word ‘potash’, originally meaning an alkali extracted with water in a pot of ash of burned wood or tree leaves.
Potassium’s symbol K comes from ‘kalium’ the name of the element in Germany and Scandinavia.
Just a few days after isolating potassium, Davy isolatedsodium for the first time using the same method.
Discovery of Lithium
Lithium was discovered by Johan Arfvedson in 1817 in Stockholm, Sweden, during an analysis of petalite (LiAlSi4O10).
He found the petalite contained “silica, alumina and an alkali.” (1)
The new alkali metal in the petalite had unique properties.
It required more acid to neutralize it than sodium and its carbonate was only sparingly soluble in water – unlike sodium carbonate.
The new alkali differed from potassium because it did not give a precipitate with tartaric acid.
Arfvedson tried to produce a pure sample of the new metal by electrolysis, but he was unsuccessful; the battery he used was not powerful enough. (2)
The pure metal was isolated the following year by both Swedish chemist William Brande and English chemist Humphry Davy working independently.
Davy obtained a small quantity of lithium metal by electrolysis of lithium carbonate. (3)
He noted the new element had a red flame color somewhat like strontium and produced an alkali solution when dissolved in water.
In days less safety-conscious than the present, Brande said of lithium, “its solution tastes acrid like the other fixed alkalies.” (4)
By 1855 Robert Bunsen and Augustus Matthiessen were independently producing the metal in large quantities by electrolysis of molten lithium chloride.
Lithium’s name is derived from the Greek word ‘lithos’ meaning, ‘stone.’
Discovery of Carbon
Carbon has been known since ancient times in the form of soot, charcoal, graphite and diamonds. Ancient cultures did not realize, of course, that these substances were different forms of the same element
French scientist Antoine Lavoisier named carbon and he carried out a variety of experiments to reveal its nature.
In 1772 he pooled resources with other chemists to buy a diamond, which they placed in a closed glass jar. They focused the sun’s rays on the diamond with a remarkable giant magnifying glass and saw the diamond burn and disappear.
Lavoisier noted the overall weight of the jar was unchanged and that when it burned, the diamond had combined with oxygen to form carbon dioxide. He concluded that diamond and charcoal were made of the same element – carbon.
In 1779, Swedish scientist Carl Scheele showed that graphite burned to form carbon dioxide and so must be another form of carbon.
In 1796, English chemist Smithson Tennant established that diamond was pure carbon and not a compound of carbon; it burned to form only carbon dioxide.
Tennant also proved that when equal weights of charcoal and diamonds were burned, they produced the same amount of carbon dioxide.
In 1855, English chemist Benjamin Brodie produced pure graphite from carbon, proving graphite was a form of carbon
Although it had been previously attempted without success, in 1955 American scientist Francis Bundy and coworkers at General Electric finally demonstrated that graphite could be transformed into diamond at high temperature and high pressure.
In 1985, Robert Curl, Harry Kroto and Richard Smalley discovered fullerenes, a new form of carbon in which the atoms are arranged in soccer-ball shapes. The best known fullerene is buckminsterfullerene, also known as C60, consisting of 60 carbon atoms. A large family of fullerenes exists, starting at C20 and reaching up to C540.
The most recently discovered allotrope of carbon is graphene, which consists of a single layer of carbon atoms arranged in hexagons. If these layers were stacked upon one other, graphite would be the result. Graphene has a thickness of just one atom.
Graphene’s discovery was announced in 2004 by Kostya Novoselov and Andre Geim, who used adhesive tape to detach a single layer of atoms from graphite to produce the new allotrope.
Discovery of Oxygen
Oxygen was discovered in 1774 by Joseph Priestley in England and two years earlier, but unpublished, by Carl W. Scheele in Sweden.
Scheele heated several compounds including potassium nitrate, manganese oxide, and mercury oxide and found they released a gas which enhanced combustion.
Priestley heated mercury oxide, focusing sunlight using a 12-inch ‘burning lens’ – a very large magnifying glass – to bring the oxide to a high temperature. Priestley’s lens was smaller than the enormous one used by Antoine Lavoisier in his investigation of carbon. (Shown on Chemicool’s carbon page.)
Totally unexpectedly, the hot mercury oxide yielded a gas that made a candle burn five times faster than normal. Priestley wrote: “But what surprised me more than I can well express was that a candle burned in this air with a remarkably vigorous flame. I was utterly at a loss how to account for it.” )
In addition to noticing the effect of oxygen on combustion, Priestley later noted the new gas’s biological role. He placed a mouse in a jar of oxygen, expecting it would survive for 15 minutes maximum before it suffocated. Instead, the mouse survived for a whole hour and was none the worse for it.)
Antoine Lavoisier carried out similar experiments to Priestley’s and added to our knowledge enormously by discovering that air contains about 20 percent oxygen and that when any substance burns, it actually combines chemically with oxygen.
Lavoisier also found that the weight of the gas released by heating mercury oxide was identical to the weight lost by the mercury oxide, and that when other elements react with oxygen their weight gain is identical to the weight lost from the air.
This enabled Lavoisier to state a new fundamental law: the law of the conservation of matter; “matter is conserved in chemical reactions” or, alternatively, “the total mass of a chemical reaction’s products is identical to the total mass of the starting materials.”
In addition to these achievements, it was Lavoisier who first gave the element its name oxygen.
The word oxygen is derived from the Greek words ‘oxys’ meaning acid and ‘genes’ meaning forming.
Before it was discovered and isolated, a number of scientists had recognized the existence of a substance with the properties of oxygen:
In the early 1500s Leonardo da Vinci observed that a fraction of air is consumed in respiration and combustion.
In 1665 Robert Hooke noted that air contains a substance which is present in potassium nitrate [potassium nitrate releases oxygen when heated,] and a larger quantity of an unreactive substance [which we call nitrogen].
In 1668 John Mayow wrote that air contains the gas oxygen [he called it nitroarial spirit], which is consumed in respiration and burning.
Mayow observed that: substances do not burn in air from which oxygen is absent; oxygen is present in the acid part of potassium nitrate [i.e., in the nitrate - he was right!]; animals absorb oxygen into their blood when they breathe; air breathed out by animals has less oxygen in it than fresh air.
Discovery of Hydrogen
A favorite school chemistry experiment is to add a metal such as magnesium to an acid. The metal reacts with the acid, forming a salt and releases hydrogen from the acid. The hydrogen gas bubbles up from the liquid and students collect it in small quantities for further experiments, such as the ‘pop-test.’
The first recorded instance of hydrogen made by human action was in the first half of the 1500s, by a similar method to that used in schools now. Theophrastus Paracelsus, a physician, dissolved iron in sulfuric acid and observed the release of a gas. He is reported to have said of the experiment, “Air arises and breaks forth like a wind.” He did not, however, discover any of hydrogen’s properties.
Turquet De Mayerne repeated Paracelsus’s experiment in 1650 and found that the gas was flammable. Neither Paracelsus nor De Mayerne proposed that hydrogen could be a new element. Indeed, Paracelsus believed there were only three elements – the tria prima – salt, sulfur, and mercury – and that all other substances were made of different combinations of these three. (Chemistry still had a long way to go!)
In 1670, English scientist Robert Boyle added iron to sulfuric acid. He showed the resulting (hydrogen) gas only burned if air was present and that a fraction of the air (we would now call it oxygen) was consumed by the burning.
Hydrogen was first recognized as a distinct element in 1766 by English scientist Henry Cavendish, when he prepared it by reacting hydrochloric acid with zinc. He described hydrogen as “inflammable air from metals” and established that it was the same material (by its reactions and its density) regardless of which metal and which acid he used to produce it.(1) Cavendish also observed that when the substance was burned, it produced water.
French scientist Antoine Lavoisier later named the element hydrogen (1783). The name comes from the Greek ‘hydro’ meaning water and ‘genes’ meaning forming – hydrogen is one of the two water forming elements.
In 1806, with hydrogen well-established as an element, English chemist Humphry Davy pushed a strong electric current through purified water.
He found hydrogen and oxygen were formed. The experiment demonstrated that electricity could pull substances apart into their constituent elements. Davy realized that substances were bound together by an electrical phenomenon; he had discovered the true nature of chemical bonding.
حال ساده:Simple present tense
الگوی ساخت: مصدر بدون to+فاعل
(usage):
1- بین كار های عادی و تكراری
مثال: . I usually get up at 9.00 every da -
- موارد كاربرد زمان حال ساده
تبادل
لینک هوشمند
