Science: Nervous Elements

At the Manhattan meeting of the American Chemical Society last week, two novel elements made radioactive bows. One was man-made curium, No. 96 in the periodic table and the heaviest element known. The creation of curium was announced in 1945 (TIME, Nov. 26, 1945). But the element was not “isolated” (purified chemically) until recently. The world’s total supply, prepared by Drs. Isadore Perlman and L. B. Werner of the University of California, is barely big enough to be seen with the naked eye.

No. 96. Like all the four known artificial elements,† curium is unstable. Each millionth of a gram shoots out 70 billion alpha particles (helium nuclei) per minute, 3,000 times as many as the same amount of radium. This activity makes a solution of curium hydroxide glow strongly enough to take its own photograph. Its “half-life” (the period during which one half disintegrates) is only five months.

Curium can be made by bombarding plutonium with alpha particles, or americium with neutrons. Now that it has been isolated, the scientists working under the Atomic Energy Commission (the only ones privileged to play around with plutonium and its relatives) can try to build up an Element 97.

No. 61. Other element-hunters polished off some unfinished business. Two young nuclear chemists, J. A. Marinsky and L. E. Glendenin of M.I.T., announced that while working at Oak Ridge, Tenn. they had synthesized and isolated Element 61, thus filling the last gap in the periodic table. They had extracted the missing element from the miscellaneous “fission products” formed by uranium atoms splitting in the Oak Ridge pile, and had also built it up by bombarding Element No. 60 (neodymium) with neutrons.

As a chemical element, No. 61 is not good for much; it is almost as unstable as curium. The longest-lasting of its two isotopes has a half-life of 3.7 years.

At the chemists’ meeting last week, Dr. B. Smith Hopkins, 74, retired professor at the University of Illinois, rose to defend his priority on No. 61. In 1926, he insisted, he had found the element by observing its spectrum. Other experts testified that he must have made a mistake. Chief count against Dr. Hopkins’ claim: Element 61 is so short-lived that it could hardly have existed in nature.

Until the question of priority is settled, Element 61 will have no official name. Dr. Hopkins has called it illinium. Mr. Glendenin wants to call it prometheum after the Greek god Prometheus, giver of fire. One convention wag suggested grovesium, after loud-mouthed Major General Leslie R. Groves, military chief of the atom bomb project. Chemical symbol: Grr.

† The others: neptunium, No. 93; plutonium, No. 94; americium, No. 95.