There’s a new heavy in town. Element 112, a “superheavy” element with an atomic mass of 278, has been officially named copernicium, the International Union of Pure and Applied Chemistry announced February 19. It is the heaviest named element to date.
Scientists hope the new element is a stepping stone toward the predicted “island of stability,” a region of the periodic table where researchers expect to find new superheavy elements. These new elements may last longer than a few seconds—most heavy elements are unstable—and might be exploited for purposes still unknown.
“One of the exciting things is, how far can we keep going?” says nuclear chemist Paul Karol of Carnegie Mellon University in Pittsburgh. “We might find something that is stable and has unusual applications.”
A team led by Sigurd Hofmann of the Center for Heavy Ion Research, or GSI, in Darmstadt, Germany, created copernicium, symbol Cn, in 1996 by bombarding a lead target (each lead atom has 82 protons) with zinc isotopes (with 30 protons). It took a week to create one atom of the stuff, Hofmann notes in a commentary in the February Nature Chemistry. And it took 14 years of follow-up research for Hofmann’s team and other researchers to validate the feat to the satisfaction of the IUPAC.
Forcing two nuclei together is no small task, says John W. Jost, former director of IUPAC, which is headquartered in Research Triangle Park, N.C. It requires breaking through the barrier of electrostatic repulsive forces that act at larger scales in the atom to get to the attractive forces binding the nucleus, and using those forces to lasso two nuclei together. Even once such fusion has occurred, the product decays almost instantaneously. Researchers then must piece together this “decay chain” to figure out what element they created. The whole process is akin to “shooting a piston from outside a barn at an engine inside,” says Jost. “Once in a while it goes in the right spot and you’ve got a piston inside a cylinder, but then the engine falls apart.”
Uranium, with 92 protons, is the heaviest element that appears naturally in significant quantities. Scientists have synthesized all of the heavier, or “transuranic,” elements in the lab. Hofmann and his colleagues, who had previously made elements 107 to 111, used the Universal Linear Accelerator in Darmstadt to make copernicium. The 120-meter-long accelerator shoots ions at about 10 percent the speed of light.
Sitting below zinc, cadmium and mercury in the periodic table, copernicium may behave similarly to these transition metals, which are known for being comfortable with more than one configuration of electrons. Copernicium might be more volatile than mercury but still be liquid at room temperature, Hofmann speculates.
Copernicium is named for the Renaissance astronomer Copernicus, who is best known for turning the earth-centered view of the universe inside out by presenting the first fully conceived theory of a planetary system centered on the sun rather than the Earth. The beauty of the name, Hofmann notes, is that Copernicus’ concept of an attractive central object holding smaller ones in orbit around it is much like an atom writ large.