Thursday, August 14, 2008

The Elements

Hansisgreat features a regular column on the Periodic Table of Elements (shown right), which organizes the basic elements which combine to form all matter in the Universe. Many of these elements are familiar, the three I'm posting on today are extremely rare and almost completely unknown to non-scientists. In fact, I'd barely even heard of them before researching them for this post.

In spite of their obscurity, they seem to have some interesting uses. In fact, if you use a computer and drive a car, you use two of these three "unknown" elements every day.

Please enjoy...

Technetium:
Atomic Symbol: Tc
Atomic Number: 43
The longest-lived isotope of technetium (pronounced tek-nee-see-um) has a half-life of only 4 million years, which means any technetium present when the Earth formed 4.5 billion years ago would now be long gone. The discovery of this element on Earth proved that stars are the furnaces in which the chemicals elements are being manufactured. Since stars like the Sun can't produce elements heavier than iron, it is therefore supposed that very heavy elements like gold and uranium must have been formed by supernovas, which also have very high concentrations of technetium.
Technetium is rarely encountered outside nuclear facilities, is highly radioactive, and is adding to the planetary burden of unwanted nuclear waste.

Ruthenium:
Atomic Symbol: Ru
Atomic Number: 44
One of the rarest metals on Earth, demand for Ruthenium is rising. In electronics, it is used for electrical contacts and in microchips. It is also used in the chemical industry for the production of ammonia from natural gas.
One radioactive isotope (Ru-106) is produced by nuclear reactors and has thus contaminated the food chain. It is easily absorbed by algae and seaweed, with large amounts detected in the Irish Sea because of the nearby nuclear facility at Sellafield, UK.

Rhodium:
Atomic Symbol: Rh
Atomic Number: 45
Most rhodium produced commercially goes into catalytic converters for cars, because it is excellent at reducing emissions of poisonous nitric oxides. Demand for the metal is so high that it is reclaimed from exhausted converters, producing 2 tons of the metal per year. It is also used to coat electrical contacts and in spark plugs.
A rhodium compound, discovered by Nobel Prize winner Geoffrey Wilkinson, was found to be excellent at speeding up chemical reactions. It is now widely used in the chemical production industry, and is known as Wilkinson's catalyst.

For my posts on the previous elements, click here.

There's an outstanding book called Nature's Building Blocks: An A-Z Guide to the Elements, by John Emsley. It's been an invaluable resource during my research for this series, and has a place in the home of every chemistry enthusiast.

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