Titanium (22)

Titanium is a lustrous, white metal when pure. Titanium minerals are quite common. The metal has a low density, good strength, is easily fabricated, and has excellent corrosion resistance. The metal burns in air and is the only element that burns in nitrogen. It is marvelous in fireworks.

Titanium is resistant to dilute sulphuric and hydrochloric acid, most organic acids, damp chlorine gas, and chloride solutions. Titanium metal is considered to be physiologically inert.

Titanium is present in meteorites and in the sun. Some lunar rocks contain high concentrations of the dioxide, TiO2. Titanium oxide bands are prominent in the spectra of M-type stars.

•Name: Titanium
•Symbol: Ti
•Atomic number: 22
•Atomic weight: 47.867
•Standard state: solid at 298 K
•CAS Registry ID: 7440-32-6
•Group in periodic table: 4
•Period in periodic table: 4
•Block in periodic table: d-block
•Color: silvery metallic
•Classification: Metallic

Historical information

Titanium was discovered by William Gregor at 1791 in England, who was interested in minerals.  It was named after the "Titans", (the sons of the Earth goddess in Greek mythology).  He recognized the presence of a new element, now known as titanium, in menachanite, a mineral named after Menaccan in Cornwall (England). Several years later, the element was rediscovered in the ore rutile by a German chemist, Klaproth.

The pure elemental metal was not made until 1910 by Matthew A. Hunter, who heated TiCl4 (titanium tetrachloride) together with sodium in a steel bomb at 700-800°Celsius.

Physical properties

•Melting point: 1941 [or 1668 °C (3034 °F)] K
•Boiling point: 3560 [or 3287 °C (5949 °F)] K
•Density of solid: 4507 kg m-3

Orbital properties

•Ground state electron configuration: [Ar].3d2.4s2
•Shell structure: 2.8.10.2
•Term symbol: 3F2

Isolation

Titanium is readily available from commercial sources so preparation in the laboratory is not normally required. In industry, reduction of ores with carbon is not a useful option as intractable carbides are produced. The Kroll method is used on large scales and involves the action of chlorine and carbon upon ilmenite (TiFeO3) or rutile (TiO2). The resultant titanium tetrachloride, TiCl4, is separated from the iron trichloride, FeCl3, by fractional distillation. Finally TiCl4 is reduced to metallic titanium by reduction with
magnesium, Mg. Air is excluded so as to prevent contamination of the product with oxygen or nitrogen.

2TiFeO3 + 7Cl2 + 6C (900°C) → 2TiCl4 + 2FeCl3 + 6CO

TiCl4 + 2Mg (1100°C) → 2MgCl2 + Ti

Excess magnesium and magnesium dichloride is removed from the product by treatment with water and hydrochloric acid to leave a titanium "sponge". This can be melted under a helium or argon atmosphere to allow casting as bars.

Interesting facts:

Titanium is used in alloys with aluminum, molybdenum, manganese, and iron. Most of these alloys are used in the aerospace industry such as airframes and engines. It is used because it is strong, lightweight, and has the ability to withstand extreme temperatures.

Titanium is as strong as steel and much lighter. It is twice as strong as aluminum and nearly as resistant to corrosion as platinum.

Titanium is also used in joint replacement parts such as hip, ball and joint sockets.

Titanium has excellent resistance to sea water so it is used for propeller shafts, rigging, and other parts of a ship exposed to salt water. Titanium anodes coated with platinum provides cathodic protection from corrosion.

Titanium paint reflects infrared radiation so it is extensively used in solar observatories where heat could cause poor viewing conditions.

Titanium dioxide has an optical dispersion higher than a diamond.

Titanium dioxide is also used in paint because it has good covering power