Element of the Month: Radon!

September's Element of the Month:

The Thinker, probably the best-known work of Auguste Radon,
actually exists in many... what? It isn't? Well, never mind.

Radon!
Rn
86

Atomic Mass: 222ish amu
Melting Point: -71 °C
Boiling Point: -61.7 °C

Mining is surely one of the most dangerous things a human can do in the course of a career. One of the many, many, many dangers involved is something that they used to call the mala metallorum. This “metal disease” was lung cancer – a much rarer thing in the Western medical tradition before Spanish adventurers in the Caribbean discovered the joys of nicotine – and the reason that miners were vulnerable is because they were breathing in Radon.

In a way, Radon is fairly insidious stuff. It’s a colorless and odorless gas, and therefore basically undetectable. It is also heavy as Lead (heavier, actually: Lead is element 82), so even though it is a gas it doesn’t exactly swirl and billow. It tends to sink and, if it’s in an enclosed space, to stay where it is. Does this mean that Renaissance miners were descending into vast enclosed underground pools of Radon? No, it doesn’t. Radon is produced very, very gradually by the breakdown of Thorium and Uranium, neither of which are especially predominant in bedrock, or even in their own ores. Also, Radon’s half-life is less than four days. So it’s not that there is a ton of Radon about, just that in certain enclosed spaces – a mine, or an overzealously weather-tight basement – a tiny amount of Radon can go a long, long way.

The Centerfold!

This ordinary household glass might be 1/3 filled
with Radon.  But probably not.  You could tell
for sure by picking it up, but I wouldn't recommend that.

So, let’s say there is an atom of Radon pushed up into your basement along with other gasses released from minerals in the soil and rocks underneath your house. If it is a perfectly average atom, it will decay in a well-mannered fashion just as its half-life comes around, at 3.8 days. “Whew!” you think, “it’s gone.” But no, now you’ve got a hot little atom of radioactive Polonium, which will hang around for a median of three minutes before itself decaying into a radioactive isotope of lead for a half hour. Bismuth, for 20 minutes! Another form of Polonium, for a tiny tiny fraction of a second! Another form of radioactive lead, for… 22 years. After which there are still a few steps, through another form of Bismuth and another form of Polonium, before you’ve finally got a nice, innocent form of lead. But in the meantime, if any of those little solid radioactive particles adhered to basement dust, and you breathed in that dust particle, then you would have a tiny tiny chance that that little atom could have nasty consequences. The more such dust particles inhaled, of course, the worse the danger.

Radon in the basement is a well-known issue these days, but it’s an example of how sneaky this element is that the problem was only discovered around 1980, when somebody noticed that some nuclear power plant employees were more radioactive showing up for work than they were when they left for home. If you poke around, you can find figures showing what the danger threshold is for Radon content in your basement or your mine, and also estimates of how many people die each year of the mala metallorum. There is a great deal of guesswork involved in all this, however, because the leading cause of lung cancer (see “joys of nicotine,” above) is so very, very prevalent that it makes it difficult to put together a good methodology for studying all the other causes of lung cancer. Radon exposure is apparently a strong candidate for cause #2.

Brainy German Friedrich Ernst Dorn is generally given credit for discovering Radon, in 1900. He called it “Radium Emanation,” though, and later scientists made fun of him for coming up with such a clunky name. Ten years later, Radon was isolated by brainy British guys Sir William Ramsay and Robert Whytlaw-Gray. Sir Ramsey also discovered Neon, Krypton, and Xenon, and was the first person to isolate Helium.  Dude won the Nobel Prize for discovering the Noble Gasses!  No, really, he did! Aside from his work on Radon, Whytlaw-Gray is best remembered for ending up in the hospital after blowing up his lab in an experiment, thus making an important contribution to our modern stereotype of the book-brilliant but comically inept experimental scientist.