My Experiences with Radioactive Elements

I’ve recently been reading about the elements, and particularly about the rarer ones. Radioactive elements tend to be among the rarer ones on earth. In my life, not counting glow-in-the-dark radium dials/paint, radon emissions from e.g. granite, or other household traces of radioisotopes, I’ve had two interesting encounters with radioactive elements.

The first time I met a radioactive element was in high school, as part of my physics class. Of course we studied radioactivity, α-, β- and γ-decay; used a cloud chamber, etc. According to my teacher, the element we used was protactinium. I’m wondering now whether it really was. Protactinium is extremely rare, and as I understand it, basically occurs in uranium ore as a daughter product of a radioactive decay chain. Theodore Gray, well-known element collector and purveyor of fine posters, says:

“Astatine, francium, actinium, and protactinium are irritating to element collectors. … The problem is that astatine, francium, actinium, and protactinium are absolutely impossible to collect in any meaningful sense of the word. They are so fantastically radioactive and short-lived that if you had a visible quantity of any of them, you would be dead and then it would vanish before your body was cold.”

On the other hand, wikipedia says that 231-Pa has a half-life of 32760 years, and:

“In 1961, the United Kingdom Atomic Energy Authority was able to produce 125 g of 99.9% pure protactinium, processing 60 tons of waste material in a 12-stage process and spending 500,000 USD. For many years, this was the world’s only supply of the element. It is reported that the metal was sold to laboratories for a cost of 2,800 USD / g in the following years.”

It is therefore perhaps plausible that a fraction of a gram of 231-Pa made its way to my high school for use in physics class.

The next time I met a radioactive element was in first-year physics at university. I think the element this time was uranium 238, a relatively common element of the radioactive ones. And the application was a cool one: we repeated Ernest Rutherford’s experiment firing α-particles through gold foil and thus debunking the “plum-pudding” model of atomic structure.

The rest of my first year physics practicals were to do with gyroscopes and various kinds of electronics, and after the first year, physics was no longer on my syllabus – it was all computer science, all the time. So I haven’t played with any radioactive substances since then.

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