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PROTACTINIUM

LINDA RABER, C&EN WASHINGTON

" Don't call it transmutation. They'll have our heads off as alchemists!"Ernest Rutherford warned his colleague Frederick Soddy in 1901. But transmutation it was--and transmutation would be the theme during Soddy's life (1877–1956).

Soddy was one of the discoverers of protactinium, but this was a minor accomplishment, considering that it was Soddy who elucidated the concept of isotopes--the existence of elements of identical chemical properties yet different atomic masses--for which he received the 1921 Nobel Prize in Chemistry. Soddy also theorized and then proved that radioactivity is accompanied by a chemical "transmutation" of the elements--that is, one element changing into another element by nuclear decay. Hence Rutherford's warning.

Protactinium was first identified by Kasimir Fajans and O. H. Göhring in 1913 while they were studying uranium's decay. They found protactinium-234, which, because of its short half-life (1.17 minutes), they called "brevium." The element's existence was confirmed in 1918 when protactinium-231 was independently discovered by Otto Hahn and Lise Meitner in Germany and Soddy and John Cranston in Scotland. Its name was changed from brevium to protoactinium and then shortened to protactinium in 1949.

Soddy
SCIENCE PHOTO LIBRARY
Soddy was not a traditional alchemist; his work was not about turning base metals into gold--far from it. "Energy, not gold, will be the quest of the modern scientific alchemist," Soddy wrote. He envisioned nuclear scientists contributing to the good of humanity. By the discovery of the immense stores of energy in the atomic nucleus, he wrote, "it, for the first time, transpires that the hard struggle for existence on the bare leavings of natural energy in which the race has evolved is no longer the only possible or enduring lot of Man. It is a legitimate aspiration to believe that one day he will attain the power to regulate for his own purposes the primary fountains of energy which Nature now so jealously conserves for the future."

He envisioned a future Eden-like Earth with clean air and water and untold energy that could never be used up--and an end to poverty and suffering. And scientists had the privilege and the responsibility to bring this wealth to humanity. According to biographer Linda Merricks, during lectures Soddy gave in Aberdeen, Scotland, in 1914, he "pointed out that the potential energy contained in radium, which was a million times greater than the same weight of coal, would, if it could only be harnessed, provide a cheap and clean source of energy which could be turned into work."

But Soddy had seen that science applied to world needs could also be applied to destructive purposes. One example, particularly striking at the time, was that the 1909 development by Fritz Haber and Carl Bosch of a high-pressure synthesis of ammonia on a large scale for the production of fertilizers could also be used in armaments. If a productive process like making fertilizers to feed a hungry world could be transmuted in such a way, then the problems for atomic power were going to be enormous. These thoughts weighed heavily on Soddy, who was thankful that no method of controlling the release of atomic energy had been developed. He hoped "that we should not discover it until Man was living at peace with his neighbors." It wasn't to be.

Soddy left science and refrained from performing any work that might further the achievement of controlled atomic energy. He changed his research focus to economics, particularly to monetary theory. This transmutation didn't go over well. According to Thaddeus J. Trenn, a physicist and historian of science and religion at the University of Toronto: "It has often been said of Soddy that he went 'off the rails' about 1919. ... His ensuing excommunication from the scientific community was conducted with the same righteous vigor as was his exclusion from the esoteric circle of economists. He was loved by neither and despised by all."

All the while, artistic, political, and scientific minds responded to the atom's potential. Soddy's lectures, published in 1909 as "The Interpretation of Radium" were used by H. G. Wells in his novel "The World Set Free," which he dedicated to Soddy. The book was published weeks before the outbreak of World War I.

In the novel, prescient Wells describes the first splitting of the atom and a war in Europe in which cities are destroyed by atom bombs dropped from aircraft. Later in the book, Wells describes the bomb sites as remaining poisonous. In the mid-1930s, Wells's book, imbued with Soddy's ideas, set Leo Szilard thinking about the possibility of chain reactions and how they might be used to create such a bomb. Or at least that's how the story goes.

In 1953, having seen the realization of his worst fears in Hiroshima and Nagasaki, Soddy wrote, "We have to find out how it comes about that science, which, without economic exhaustion, provided the sinews of war for the most colossal and destructive conflict in history, with the manpower of the nations engaged in military service, has not yet abolished poverty and degrading conditions of living from our midst in the piping times of peace." We still ask.


Linda Raber heads the ACS News & Special Features department of C&EN. She had the happy task of finding writers for most of these essays.

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PROTACTINIUM AT A GLANCE
Name: From the Greek protos, first, and actinium, element 89. Protactinium forms actinium when it decays.
Atomic mass: 231.04.
History: Discovered in 1913 by Kasimir Fajans and O. H. Göhring while studying uranium decay.
Occurrence: Naturally occurring, short-lived member of the uranium-238 decay series. It can be isolated in small amounts from some uranium ores, such as pitchblende.
Appearance: Silvery metal.
Behavior: Toxic and extremely radioactive.
Uses: No commercial uses. Pa

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