Titanium
Titanium is a transition metal element denoted by the atomic symbol Ti. It has an atomic number of 22 and the average atomic weight of its five natural isotopes is 47.88. It has a melting point of 3,020 ± 50°F (1,660 ± 10°C) and a boiling point of 5,948.6°F (3,287°C). The element occurs as a bright, lustrous, brittle metal or a dark gray powder. It is the ninth most common element with an abundance of 0.63% by weight in the earth's crust. Titanium has also been found in meteorites, in moon rocks, and in the sun and other stars.
The first mention of titanium appears in the writings of an English clergyman and amateur scientist, William Gregor (1761-1817). In 1791, Gregor described his analysis of a mineral obtained from a valley in the Menachan region of Cornwall. He reported that the mineral contained a "reddish brown calx" that he could not identify and that he thought might include "a new metallic substance." Gregor's report was printed in a European journal, Crell's Annalen; it was largely ignored, and his discovery was soon forgotten.
In 1795, however, Martin Heinrich Klaproth decided to re-study the menchanite analyzed by Gregor. Klaproth concluded that Gregor had been correct in his analysis and that he had, indeed, found a new element. Klaproth suggested the name titanium for the new substance identified in the mineral. Klaproth had recently found the same substance in a sample of rutile from Hungary that he had been asked to analyze. He proposed naming the new metal after the Titans, the first sons of the earth according to mythology.
The production of pure titanium metal proved to be a major challenge for chemists. Samples of 95 percent purity and 98 percent purity were prepared, respectively, by Lars Nilson (1840-1899) and Sven Otto Pettersson (1848-1941) in 1887, and by Ferdinand Moissan (1852-1907) in 1895. Finally, in 1910, M. A. Hunter prepared a sample of the element that was 99.9 percent pure.
Titanium has a variety of uses. The most important use of titanium is in alloys. Titanium alloys are very strong for their weight and can withstand large changes in temperature. These properties make them valuable in the manufacture of parts for airplanes and space craft. Titanium's resistance to salt water has made it useful in alloys used in propeller blades and shafts and other ship parts. The same property suggests that it may find application in desalinizing plants. Titanium dioxide, TiO2, is the most widely use compound of the element. Since the use of lead compounds have been discontinued in paints, it has become the most popular pigment in white paint. The oxide is also used as a coloring in foods, ceramics, plastics, inks, and enamels, and as a filler and coater in paper. Titanium tetrachloride is a liquid that reacts with ammonia to produce large volumes of smoke, such as are used in sky-writing.
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