As we close out the year, Bill Langer acknowledges some of the elements on the Periodic Table, which was first formulated 150 years ago.
You may have noticed that over the past few months that I have discussed some of the elements on the Periodic Table, which this year is 150 years old.
This article describes some special elements with properties or their uses that might surprise you:
• Sulfur (or sulphur, S – Atomic Number 16), infamous for a smell comparable to rotten eggs, is actually a tasteless, odourless non-metal. The smell associated with sulfur is actually characteristic of hydrogen sulfide (H2S). While sulfur may not seem odd to most people, it has a curious property – it changes colour. In its native form sulfur is a yellow crystalline solid. But if you melt sulfur, it becomes a blood red liquid, and if you burn sulfur, a neon blue flame is produced. You might say it is the “chameleon” of the elements.
• Gallium (Ga – Atomic Number 31) is a soft metal that doesn’t occur in pure form in nature but can readily be smelted from minerals. It is used in semi-conductor production, mainly for light-emitting diodes (LEDs), laser diodes, and solar panels. It is also used to create brilliant mirrors. What’s amazing is that gallium does something that metals aren’t supposed to do – it melts in a human hand, then re-solidifies once it cools down below its 29oC (or 85oF) melting point. That property made it the basis for chemist pranks involving gallium utensils at meals.
• Antimony (Sb – Atomic number 51) is a rare element occasionally found in its pure form but mostly in the mineral stibnite. Antimony has a number of industrial uses, but perhaps its most notorious property is that, along with arsenic and mercury, it is among the deadliest elements on the Periodic Table. However, that didn’t stop people from ingesting it. In the 18th century, pills of antimony were popular as a laxative. It worked so well that some people would root through their excrement to retrieve the pill and reuse it later. About that same time, tartar emetic, an efflorescent crystalline salt with a sweetish metallic taste, was a popular hangover cure. Wolfgang Amadeus Mozart, a heavy drinker, was known to overindulge in the cure. Unfortunately, tarter emeric contains antimony, which some speculate led to his death.
• Iridium (Ir – Atomic number 77) is the most corrosive-resistant element and can’t be affected by water, chemicals or acids. Iridium also is the second most dense element. Consequently, it is rare on earth because it sank into the centre of the planet as the planet was formed. But iridium can be found in large concentrations in asteroids and likely comprised part of the meteorite that wiped out the dinosaurs 65 million years ago. Scientists have found that geologic rocks at the Cretaceous Tertiary boundary, which marks the extinction of the dinosaurs, contain more than 100 times the quantities of iridium than normally expected.
• Bismuth (Bi – Atomic Number 83) – Bismuth is the heaviest non-radioactive metal, which lends its name and pink colour to a famous over the counter medicine in the US – Pepto-Bismol (known as peptosyl in Australia). But its most curious property is that it is diamagnetic. That means if you place a magnet between two pieces of bismuth, it will levitate indefinitely.
The Periodic Table is one of the most important, influential scientific achievements. It reflects the essence not only of chemistry, but also of physics, biology, geology, and other basic sciences disciplines. So, on its 150th anniversary, I say …
Bill Langer is a consultant geologist.