Sciency Words: Island of Stability

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:

ISLAND OF STABILITY

According to Star Trek: Voyager, in the 24th Century there will be 246 elements on the periodic table. In one episode, the Voyager crew discovers element 247, and to their astonishment that element is stable.

Here in the 21st Century, on modern day Earth, there are only 91 naturally occurring elements. Element 43, technetium, and everything above element 92, uranium, have to be produced artificially. And these artificial elements are all unstable. Some of them, especially the really, really high numbered ones, are so unstable that they’re effectively useless.

When an atomic nucleus gets too big, the so-called strong nuclear force is no longer strong enough to hold the whole thing together. You can also run into problems if you don’t have a comfortable balance of protons and neutrons. At that point, when atoms are too big or improperly balanced, they start shedding nuclear particles until they can stabilize themselves. This process is called radioactive decay.

If you want, you can draw a chart with the number of protons in an atom along one axis and the number of neutrons along the other. But charts are boring, so let’s draw a map instead.

Physicist Glenn Seaborg (for whom element 106, seaborgium, is named) was apparently a big fan of maps. I imagine he and J.R.R. Tolkein would have gotten along well. In the 1960’s, Seaborg started referring to groups of atomic isotopes by “geographical” names, and these names have stuck.

On the map above, the landmass stretching up from the bottom left corner represents all the stable and semi-stable isotopes. This “Peninsula of Stability” is surrounded by a “Sea of Instability.” But somewhere out in that sea, according to Seaborg and others, certain very large atoms might theoretically become stable. These atoms would have just the right balance of protons and neutrons to hold themselves together despite their extreme size. These “magically” stable isotopes are represented by the Island of Stability.

Physicists have been trying to find the Island of Stability for decades now, but it seems to be perpetually just over the horizon. It was once predicted that elements 110 and 114 might be stable. They’re not. I remember reading that element 118 might turn out to be stable. It didn’t. Now there’s a prediction about element 120. We’ll have to wait and see about that one.

Also there’s a possibility that we’ve been skirting along the island’s coast, so to speak. Maybe if we just add a few more neutrons to some of the unstable elements we’ve already found, they’ll stabilize. Maybe. More on that in next week’s Molecular Monday post.

Personally, I think Star Trek: Voyager was on to something. My prediction is that the Island of Stability will be found all the way out at element 247, and I recommend the IUPAC name it Janewayium.

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