Why does it take so long to add new elements to the periodic table?

Previously published Slate articles made new.
April 7 2010 2:34 PM

Periodic Discussions

It's going to take a long time for element 117 to make it onto the periodic table. Why?

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That's where the "hard" science of nuclear chemistry gives way to a campaign of persuasion and appeals to trust and judgment. Given how ambiguous this research can be, new elements aren't made official until the scientists hand off their data to a committee of the International Union of Pure and Applied Chemistry. In the case of element 112, the claims of the Darmstadt team had to be weighed alongside claims from teams in Russia, Japan, and Israel—each with its own method of creating and detecting ununbium and its own software and hardware. (No team had been able to find more than a few atoms.)

To sort all this out, the international committee had to travel to each lab and pore over its data with Talmudic precision. Members reviewed the magnetic bits on computer drives that are the only traces left of ununbium. The committee also weighed each team's reputation for doing good science. The Israeli team, for example, was notorious for making premature "discoveries" of heavy elements that fell apart under closer scrutiny.

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Nuclear scientists have come to expect these long delays—they just move on to creating new elements—but the confirmation process for element 112 was especially grueling. The committee first considered ununbium in the late 1990s, but its members disagreed over what, if anything, could be gleaned from the computer data. Then things got even more complicated. In 1999, an investigation by the University of California at Berkeley concluded that one of its heavy-element scientists, Victor Ninov, had probably forged data. (Ninov denies this.) Berkeley had hired Ninov away from the Darmstadt lab, where he'd been a co-discoverer of element 112. In light of the new accusations, the German team scrambled to check its work. At a crucial moment, it was forced to retract its claim for one of the two ununbium atoms that it had supposedly created.

The committee finally ruled against all four claims for ununbium in 2001, saying in its final report that it "would not be much swayed by arguments that depend to a large extent on statistics of speculative interpretations." The Germans redid their experiments in 2002, and found one more atom, but it took another seven years before the world would agree that the original evidence was acceptable. The delay can partly be explained by the fact that the committee was also working through competing claims for elements 113 through 116 as well as element 118.

It's possible that we're nearing the end of these debates, as scientists approach what may be the absolute limit of the periodic table. It took an amazing 10 billion billion (1019) collisions of calcium atoms on a californium target to produce one alleged atom of element 118. Getting past 118 may require orders of magnitude more precision and energy (and patience). Then again, you could argue that the table has already surpassed any reasonable, natural limit. The 1s and 0s by which we can identify ununbium are far more durable than its bundle of protons and neutrons in the real world. The discovery of new elements today comes down to philosophical judgments of what counts as "existence" and why. Obviously, whatever happened on the subatomic level 13 years ago in Germany happened regardless of how we humans interpret it. But no human could observe it directly. Science is a human venture, and our standards of what counts as proof—what counts as the creation of a new element—are debatable.

When the victorious German team gives element 112 its official name this fall (ununbium was just a placeholder), textbooks will be reprinted and schools worldwide will order new periodic tables for their walls. Many of these tables already use color-coded boxes to distinguish different types of matter: For example, yellow boxes for noble gases, blue for semiconductors, peach for alkali metals, and so on. The ultraheavy metals in the bottom row tend to be colored the same as solid, stable transition metals like iron or zinc. But it might help students even more if these boxes were rendered in a faint, almost translucent white—the perfect color for these ghosts of atoms.

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Sam Kean is the best-selling author of The Disappearing Spoon and The Violinist’s Thumb. His new book, The Tale of the Dueling Neurosurgeons, comes out May 6.