americium

Americium, element 95, was first produced in 1944 at the Manhattan Project’s Metallurgical Laboratory (now Argonne National Lab), located at the University of Chicago, by a team led by chemist Glenn Seaborg. Announcement of the discovery was delayed due to wartime security, and the first published mention of the new element is in an 11 April 1946 New York Times article.1

Seaborg explains the name in a 1948 US Atomic Energy Commission report:

The name americium (after the Americas) and the symbol Am are suggested for the element on the basis of its position as the sixth member of an actinide rare-earth series, analogous to europium, Eu, of the lanthanide series.2


1Oxford English Dictionary, americium, 3rd Edition, June 2008, Oxford University Press, accessed 21 November 2009, http://dictionary.oed.com/cgi/entry/50007160.

2Seaborg, Glenn T., Ralph A. James, and Leon O. Morgan, The New Element Americium (Atomic Number 95), United States Atomic Energy Commission, AECD-2185, January 1948, http://www.osti.gov/cgi-bin/rd_accomplishments/display_biblio.cgi?id=ACC0046&numPages=43&fp=N.

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