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discovered in the debris of a 1952 U.S. nuclear test in the Pacific, named 1955 for Italian-born U.S. physicist Enrico Fermi (1901-1954).
fermium fer·mi·um (fûr'mē-əm, fěr'-)
A synthetic radioactive metallic element whose most stable isotope is Fm 257 with a half-life of [approx] 100 days. Atomic number 100.
A synthetic, radioactive metallic element of the actinide series that is produced from plutonium or uranium. Its most stable isotope is Fm 257 with a half-life of approximately 100 days. Atomic number 100. See Periodic Table.
(Fm), synthetic chemical element of the actinoid series of the periodic table, atomic number 100. Fermium (as the isotope fermium-255) is produced by the intense neutron irradiation of uranium-238 and was first positively identified by Albert Ghiorso and coworkers at Berkeley, Calif., in debris taken from the first thermonuclear or hydrogen-bomb test explosion (November 1952), in the South Pacific. All fermium isotopes are radioactive. Mixtures of the isotopes fermium-254 (3.24-hour half-life), fermium-255 (20.1-hour half-life), fermium-256 (2.7-hour half-life), and fermium-257 (80-day half-life) can be produced by the intensive slow-neutron irradiation of elements of lower atomic number, such as plutonium.