Saturday, March 29, 2008

The Elements

Tonight is a special night for fans of these chemistry posts. These are three of the most important and interesting elements, and some of the earliest discovered and used by man. They have biological uses for all plants and animals, in fact life couldn't exist without them. We also use them in our culture for electricity, machinery, our money, and thousands of other things.

Let's give it up for...

Nickel:
Atomic Symbol: Ni
Atomic Number: 28
Much of the nickel that is mined here on Earth arrived here in the form of giant meteorites, hundreds of millions of years ago. One example is in Ontario, Canada. It is estimated to weigh 200 million tons, and supplies about 30% of the world's demand for nickel. Annual production exceeds 500,000 tons and it will last for at least 150 more years.
One remarkable alloy of the metal is nickel aluminide (Ni3Al), which has a unique property at high temperatures. It is six times stronger than stainless steel, and it gets stronger as it gets hotter. At 500oC it is twice as strong as it is at room temperature.
Another curious alloy is nitinol (55% nickel, 45% titanium), which has the ability to "remember" a previous shape that it had. Eyeglass frames made from nitinol can be bent and jump back into shape when released.

Copper:
Atomic Symbol: Cu
Atomic Number: 29
Copper beads have been excavated in Northern Iraq that were more than 10,000 years old. It was by far the earliest metal worked by man because of its low melting point.
Bronze is nine parts copper and one part tin. Adding a small amount of tin makes the alloy harder and also makes it possible to give it a sharp edge. Cultures who made this discovery moved out of the Stone Age into the so-called Bronze Age, beginning around 3000 BC.
Some of the ancient uses of bronze were spectacular. The Colossus at Rhodes was a bronze statue that was 35 meters high, but was destroyed in an earthquake only 50 years after being completed.
The blood of the octopus is blue because it relies on a blue copper compound to carry its oxygen, whereas most creatures rely on the deep red iron compound hemoglobin. Both seem to do the job equally well.

Zinc:
Atomic Symbol: Zn
Atomic Number: 30
The German Chemist Andreas Marggraf was the first to identify it as an element in 1746, but zinc had been known and used for centuries before that date. Strabo (66 BC - AD 24) mentions an ore from Cyprus that, when refined, resembled "mock silver", and that could be mixed with copper to produce brass.
Zinc oxide is mixed with plant oils in calamine lotion, and as a sun-blocker against damaging UV rays which can cause skin cancer.
Zinc sheets have often used in roofing, most famously in Paris where they created the attractive roofscapes which inspired many paintings. Zinc roofing has a long life, and may function for over 100 years without maintenance.

My posts on the previous elements are available here.

An exceptional book of reference on the subject is Nature's Building Blocks: An A-Z Guide to the Elements, by John Emsley. This and other fine volumes available through the Hansisgreat Store.

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