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Copyright (c) 2006-2014 MindTouch Inc.
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Discovered independently by William Gregor and Martin Klaproth in 1795, titanium (named for the mythological Greek Titans) was first isolated in 1910. It is a highly corrosion-resistant metal with great tensile strength. It is ninth in abundance for elements in the earth's crust.
Titanium is used for strengthening structural materials but is also useful in strengthening bones in the human body where it is used to make durable repairs since it does not react with tissue.
Most titanium metal is refined from a mineral known as rutile, \(TiO_2\). This is an intensely white powder that is also used as a high-hide paint pigment.
Named for the mineral zircon in which it can be found, zirconium was discovered in 1789 by Klaproth and eventually isolated in 1824 by Berzelius. The metal reacts with oxygen and nitrogen in the atmosphere to form a protective coating that inhibits further corrosion. It is resistant to weak acids and even forms a low-temperature superconductor when alloyed with niobium.
Zirconium finds applications in industry which suit its high corrosion resistance and strength. It is very similar to the less plentiful Hafnium (see below) and the two are very difficult to separate. Most samples of either are contaminated with small amounts of the other element.
More abundant than better known metals such as silver and gold, hafnium (from the Latin Hafnia, a name for Copenhagen) was not discovered until 1923 by Coster and de Hevesy. The reason is the similarity of hafnium to zirconium. Mendeleev had predicted the existence of element 72 but had wrongly suggested it might be found along with titanium ores. Instead it lay hidden with "pure" samples of zirconium. Later Niels Bohr predicted the arrangement of outer electrons for element 72 and it was using X-ray techniques to study this very thing that led to the identification of hafnium as a separate element (thus the connection to Copenhagen in the name for the metal: Bohr's hometown).
Hafnium metal is used in the manufacture of control rods for nuclear reactors because of its ability to absorb neutrons.
In 1964 researchers in the Soviet Union at Dubna announced their discovery of element 104. A similar claim was made by researchers at the University of California at Berkeley. The Soviet scientists claimed to have bombarded a target of Pu-242 with Ne-22, resulting in a nucleus with 104 protons and a mass number of 260. The Berkeley team used a Cf-249 target and isotopes of carbon for projectiles, resulting in isotopes of 104 with mass numbers of 257 and 259. Several other isotopes were also prepared by the American team.
The naming and priority of discovery controversy has raged ever since and Rutherfordium is the approved name selected by the IUPAC in August 1997.
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