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(Promo)
You're listening to Chemistry in its element brought to you by Chemistry World, the magazine of the Royal Society of Chemistry.
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Meera Senthilingam
This week, you may be surprised to learn just how reliant you are on this widely used element that cleans and protects our environment.
Simon Cotton
Titanium. It is notoriously hard to make, but we have come to rely on it and indeed we couldn't do without this element or its compounds today.
So, why is it so important? The most important compound is the oxide TiO2, which makes up 95% of the Ti used worldwide. We actually use 4 million tons of TiO2 each year, a lot of it for paint and other applications that need something that is bright white, insoluble and not toxic, like medicines and toothpaste. In the food industry it is additive number E171, used to whiten things like confectionary, cheeses, icings and toppings.
It is also used in sunscreens, since it is a very opaque white and also very good at absorbing UV light. The ability to absorb UV light helps the TiO2 to act as a photocatalyst. This means that when UV light falls upon it, it generates free electrons that react with molecules on the surface, forming very reactive organic free radicals. Now you don't want these radicals on your skin, so the TiO2 used in sunscreens is coated with a protective layer of silica or alumina.
In other situations, these radicals can be a good thing, as they can kill bacteria. Scientists have found that if you introduce small amounts of different elements like nitrogen or silver into the TiO2, UV light is not needed as visible light will do the same job. You can put very thin coatings of TiO2 onto glass (or other substances like tiles); these are being tested in hospitals, as a way of reducing infections.
When water gets onto this type of glass, it spreads out, so that it doesn't fog up (think car wing mirrors) and also washes away dirt. This is the basis of Pilkington's ActivT self-cleaning glass, a great British invention. Scientists are now investigating building TiO2 into the surfaces of buildings, pavements and roads, with the aim of getting rid of chewing gum and even dog mess. They are also testing road surfaces with a layer of TiO2 in it, as they think it could remove air pollutants from car exhausts.
The first titanium compound was identified by a Cornish vicar named William Gregor in , when he extracted the impure oxide. He dissolved it in acid and got a colourless solution, but found that it could be reduced by zinc to make a purple solution. He was a transition metal chemist ahead of his time. Lots of chemists tried - for over a hundred years - to get the pure metal. We now know that this is very difficult because even the normally unreactive gas nitrogen reacts with hot titanium metal to form the nitride, TiN.
Nowadays titanium is manufactured by the Kroll process. First you heat titanium dioxide with carbon to about degrees C and pass chlorine over it. This makes TiCl4. People call that "Tickle". Then you cover the Tickle with an argon blanket and react with hot magnesium [at 850 degrees C] to get the metallic element.
Titanium metal is not as cheap as iron - because it is more difficult to extract - so its applications tend to be specialist ones. Titanium metal has some very valuable properties. In practice, it is pretty unreactive because, like aluminium, it forms a thin protective layer of the oxide, so it doesn't corrode. Its density is 4.5 grams per cm3, much less than iron, so titanium alloys are important in the aerospace industry. It was used to make much of the SR-71 Blackbird, the world's fastest manned aircraft, as well as a major parts of the engines and airframe of the big passenger aircraft including 747s and Airbuses.
This metal is resistant to seawater so it finds marine applications like propeller shafts, and the Russians are said to have used it to construct submarines. Titanium isn't toxic, and it is not rejected by the body. It also connects with bone, so it has found surgical applications such as in joint replacements - especially hip joints - and tooth implants.
So there are lots of applications for titanium and its compounds - we just can't do without it.
Meera Senthilingam
GIANT ANODE supply professional and honest service.
Indeed we can't, seeing as it's in our food, sunscreen and windows, and soon may even be in our hospitals and on our roads. That was Simon Cotton from Uppingham School with the diverse uses and chemistry of titanium. Now next week, a sparkling element that makes otherwise plain minerals into precious stones.
Christopher Blanford
Of all chromium's natural occurrences, my favourites are gemstones, where a trace of the element adds a blaze of colour. As corundum, beryl, and crysoberyl, these metal oxides are colourless and obscure minerals. But add a dash of chromium, and they become ruby, emerald and alexandrite. In ruby - which is aluminium oxide with a few parts per thousand of the aluminium ions are replaced by chromium(III) ions - the chromium atoms are surrounded by six oxygen atoms. This leads to the chromium atoms strongly absorbing light in the violet and yellow-green regions. We see this as mainly red with some blue, giving, in the best cases, the characteristic pigeon-blood colour of the finest rubies.
Meera Senthilingam
Christopher Blanford explains the sparkling and colourful chemistry of chromium in next week's Chemistry in its Element. Until then I'm Meera Senthilingam from the nakedscientists.com and thank you for listening.
(Promo)
Chemistry in its element is brought to you by the Royal Society of Chemistry and produced by thenakedscientists.com . There's more information and other episodes of Chemistry in its element on our website at chemistryworld.org/elements
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Titanium is a chemical element (Ti) &#; atomic number 22 &#; and it has an atomic weight of 47.867. On the periodic table, titanium sits between manganese and cobalt, possessing a beautiful pale silver color.
Titanium is a lustrous silver metal with the highest strength-to-density ratio of any metallic element. Photograph by Alchemist-hp
Titanium was discovered in the year by the Reverend William Gregor in the county of Cornwall, south-west Britain.
On a walk one day, Reverend Gregor, while crossing a small stream, noticed a layer of black, magnetic sand. The sand resembled gunpowder in appearance. The name we use for this sand today is ilmenite &#; an ore consisting mainly of iron oxide and titanium.
Part of the sample he took was a reddish-brown color. He could see an oxide in the sample and knew it was a new metal but could not isolate it. He named the new metal &#; &#;manaccanite&#; &#; in honour of the parish of Manaccan where he lived.
A few years later in , the German chemist Martin Klaproth discovered what he thought was a new metallic element. Klaproth called his new metal &#; &#;titanium&#; &#; after the Titans from ancient Greek mythology.
Engraving of German chemist Martin Klaproth &#; , the discoverer of titanium, by Ambroise Tardieu after an original portrait by Eberhard-Siegfried Henne.
Klaproth had discovered titanium in rutile minerals from a deposit in Boinik, Hungary. In , Klaproth had the opportunity to read Gregor&#;s account of his discovery in , and Klaproth then realised that the red oxide in which he had found his titanium and the red oxide in which Gregor had found manaccanite were identical. Titanium and manaccanite were the same elements, and Gregor was given the recognition as the element&#;s true discoverer.
However, the name titanium was thought to be more fitting, and that was the name adopted by science.
It was more than a century after titanium&#;s discovery, that scientists and engineers found a way to produce a 99.9% pure sample of the element.
It was eventually isolated in by the metallurgist Matthew Hunter in Schenectady, a small town on the east side of the United States. His process included heating titanium (IV) chloride with sodium to a red hot heat in a pressure cylinder.
It took another 30 years until the commercially viable process, the Kroll Process, was invented by William J. Kroll in Luxembourg. Kroll&#;s method worked by heating titanium (IV) chloride with magnesium and made the commercial production of titanium possible. At the time, only tiny amounts of the metal were produced, and even in , the worldwide production of titanium was only 3 tons a year.
Demand for the metal continued to grow, and by global production of titanium reached 25,000 tons per annum. Today we produce well over 250,000 tons per year.
Titanium is a strong, durable and lightweight metal that is in extremely high demand by many industries. For instance, a Boeing 777 has a maximum, empty, operating weight of approximately lbs or 137.8 metric tonnes. Of that enormous weight, 59 metric tonnes is constructed from titanium.
The Boeing 777 is constructed using 59 tonnes of titanium and about two thirds of all titanium metal produced is used in aircraft engines and frames.
Its superior strength and light weight relative to other metals (steel, stainless steel, and aluminium), means titanium is used in many sporting goods such as tennis rackets, golf clubs and bicycle frames. For the same reasons, it is also used in the body of high-end laptop computers like the Apple PowerBook.
The metal is soluble in concentrated acids but not water. If you were to submerge a sheet of titanium in seawater for years, it would only have corrosion to the depth of about the thickness of a piece of copier paper. This remarkable resistance against corrosion makes titanium the perfect metal to create the hulls of submarines.
Titanium is resistant to corrosion by seawater and is used in the housings and components of ocean-deployed surveillance and monitoring devices for science and the military.
Titanium also has a significant role as an alloying agent. It is commonly smelted with other metals including aluminium, manganese, iron and some grades of stainless steel to improve their ability to be welded.
For us at Double Stone Steel, titanium is a vital part of our PVD process. Without titanium, Double Stone Steel would not have a business!
Many of Double Stone Steel&#;s PVD colored stainless steel sheets and profiles are colored using a charged ion plasma gas, consisting of a mix of titanium and other metals.
For more information, please visit titanium sheet supplier.