Thursday, October 26

Newly Discovered Element 118 Helps Chart the Seas of Instability

Here's my latest article, on Seed's Web site:

Based on the briefest of glimpses, scientists are mapping out a shadowy "island of stability," a harbor of hope within a vast and deadly "sea of instability." These modern-day Magellans are nuclear physicists, and by colliding atoms at high speeds, they are creating the heaviest elements ever seen with the hope that they will find this island: the few precious isotopes that do not decay instantaneously.

Now they've discovered the largest element yet, number 118: In a paper published recently in the journal Physical Review C, a collaboration of Russian and American researchers presents evidence for the as-yet-unnamed element. They say they observed 118 three times over a three-year search.

Atoms have dense nuclei that are composed of neutrons and positively-charged protons. The higher an element is on the periodic table, the more protons and neutrons—and therefore the more mass—a nucleus in one of its atoms has.

Creating superheavy nuclei is a delicate balancing act. Within the nucleus, two forces fight for control. The protons' electric charges make them repel each other fiercely. But the strong nuclear force, which binds protons and neutrons alike, pulls them together. For each element, there are only a few combinations of protons and neutrons—each of which is called an isotope—that will stick together long enough to count as an actual atom.

"At some point, the forces that are holding the nucleus together are not going to let another proton be shoved in there," said Nancy Stoyer, co-author of the study and a scientist at the Lawrence Livermore National Laboratory. "You put [another proton] in there and it's going to immediately break apart. At some point, we're going to reach the end of the elements. Where that is, we don't know."

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