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Meet 115, the Newest Element on the Periodic Table

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In case you forgot your high school chemistry, here's a quick refresher: An element's atomic number is the number of protons it contains in its nucleus.

The heaviest element in nature is uranium, which has 92 protons. But heavier elements-which have more protons in their nucleus-can be created through nuclear fusion. (Related: Learn how to make an element.)

The man-made 115 was first created by Russian scientists in Dubna about ten years ago. This week, chemists at Lund University in Sweden announced that they had replicated the Russian study at the GSI Helmholtz Center for Heavy Ion Research in Germany.

(See pictures of the labs where new elements are created.)

Element 115 will join its neighbors 114 and 116-flerovium and livermorium, respectively-on the periodic table just as soon as a committee from theInternational Union of Pure and Applied Chemistry (IUPAC) decides on an official name for 115.

We asked Paul Hooker, a chemistry professor at Westminster College in Salt Lake City, Utah, for his take on the latest addition to the periodic table.

So it sounds like 115 was actually created ten years ago, by a lab in Russia. Why are we just learning about its discovery?

When you find a new element, it has to be confirmed. You need two different labs to confirm it before [IUPAC] considers adding it to the periodic table.

This is the second lab coming in and repeating the same experiment, so now it's considered to be an official new element.

So what did the Russian and Swedish chemists actually do?

The way that you make new elements now is by shooting a beam of an element at another element and then seeing what happens when they collide.

In this case, the researchers used americium, which is kind of interesting because it's an unstable, radioactive element. They fired calcium atoms-which are much lighter than americium atoms-at the americium for weeks or even months. Most of the calcium atoms bounced off, but every now and then the atoms collided and instead of the calcium element bouncing off, it actually stuck to the americium element. When that happens, you get a short-lived atom with more protons in its nucleus, which is the center of the new element 115.

How did they know they created a new element if it happened so quickly? I think I read that it existed for less than a second before it decayed.

They look for the decay products. They look for telltale signs for when 115 disintegrates, by what's called alpha particle emission. When they see enough of those signals, they can say they probably formed a new element.

How do they know if a new element will be unstable or not?

There was an element 118 that was predicted to be much more stable; 115 wasn't predicted to be especially stable. We know what is stable. Certain ratios of protons to neutrons are stable. As the nucleus gets bigger and bigger, it's not stable-and then it can radioactively decay and spit out smaller particles-that means it's really not very stable.

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