Fermium
| Fermium | |||||||||||||||||||||||||||||||||||||||
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| Pronunciation | /ˈfɜːrmiəm/ ⓘ | ||||||||||||||||||||||||||||||||||||||
| Mass number | [257] | ||||||||||||||||||||||||||||||||||||||
| Fermium in the periodic table | |||||||||||||||||||||||||||||||||||||||
| Atomic number (Z) | 100 | ||||||||||||||||||||||||||||||||||||||
| Group | f-block groups (no number) | ||||||||||||||||||||||||||||||||||||||
| Period | period 7 | ||||||||||||||||||||||||||||||||||||||
| Block | f-block | ||||||||||||||||||||||||||||||||||||||
| Electron configuration | [Rn] 5f12 7s2 | ||||||||||||||||||||||||||||||||||||||
| Electrons per shell | 2, 8, 18, 32, 30, 8, 2 | ||||||||||||||||||||||||||||||||||||||
| Physical properties | |||||||||||||||||||||||||||||||||||||||
| Phase at STP | solid (predicted) | ||||||||||||||||||||||||||||||||||||||
| Melting point | 1800 K (1500 °C, 2800 °F) (predicted) | ||||||||||||||||||||||||||||||||||||||
| Density (near r.t.) | 9.7(1) g/cm3 (predicted)[1][a] | ||||||||||||||||||||||||||||||||||||||
| Atomic properties | |||||||||||||||||||||||||||||||||||||||
| Oxidation states | common: +3 +2[2] | ||||||||||||||||||||||||||||||||||||||
| Electronegativity | Pauling scale: 1.3 | ||||||||||||||||||||||||||||||||||||||
| Ionization energies |
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| Other properties | |||||||||||||||||||||||||||||||||||||||
| Natural occurrence | synthetic | ||||||||||||||||||||||||||||||||||||||
| Crystal structure | face-centered cubic (fcc) (predicted)[1] | ||||||||||||||||||||||||||||||||||||||
| CAS Number | 7440-72-4 | ||||||||||||||||||||||||||||||||||||||
| History | |||||||||||||||||||||||||||||||||||||||
| Naming | after Enrico Fermi | ||||||||||||||||||||||||||||||||||||||
| Discovery | Lawrence Berkeley National Laboratory (1953) | ||||||||||||||||||||||||||||||||||||||
| Isotopes of fermium | |||||||||||||||||||||||||||||||||||||||
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Fermium is a synthetic chemical element; it has symbol Fm and atomic number 100. It is an actinide and the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not been prepared yet.[5] A total of 20 isotopes are known, with 257Fm being the longest-lived with a half-life of 100.5 days.
Fermium was discovered in the debris of the first hydrogen bomb explosion in 1952, and named after Enrico Fermi, one of the pioneers of nuclear physics. Its chemistry is typical for the late actinides, with a preponderance of the +3 oxidation state but also an accessible +2 oxidation state. Owing to the small amounts of produced fermium and all of its isotopes having relatively short half-lives, there are currently no uses for it outside basic scientific research.
- ^ a b Fournier, Jean-Marc (1976). "Bonding and the electronic structure of the actinide metals". Journal of Physics and Chemistry of Solids. 37 (2): 235–244. Bibcode:1976JPCS...37..235F. doi:10.1016/0022-3697(76)90167-0.
- ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 28. doi:10.1016/C2009-0-30414-6. ISBN 978-0-08-037941-8.
- ^ Sato, Tetsuya K.; Asai, Masato; Borschevsky, Anastasia; Beerwerth, Randolf; Kaneya, Yusuke; Makii, Hiroyuki; Mitsukai, Akina; Nagame, Yuichiro; Osa, Akihiko; Toyoshima, Atsushi; Tsukada, Kazuki; Sakama, Minoru; Takeda, Shinsaku; Ooe, Kazuhiro; Sato, Daisuke; Shigekawa, Yudai; Ichikawa, Shin-ichi; Düllmann, Christoph E.; Grund, Jessica; Renisch, Dennis; Kratz, Jens V.; Schädel, Matthias; Eliav, Ephraim; Kaldor, Uzi; Fritzsche, Stephan; Stora, Thierry (25 October 2018). "First Ionization Potentials of Fm, Md, No, and Lr: Verification of Filling-Up of 5f Electrons and Confirmation of the Actinide Series". Journal of the American Chemical Society. 140 (44): 14609–14613. doi:10.1021/jacs.8b09068.
- ^ Kondev, F. G.; Wang, M.; Huang, W. J.; Naimi, S.; Audi, G. (2021). "The NUBASE2020 evaluation of nuclear properties" (PDF). Chinese Physics C. 45 (3) 030001. doi:10.1088/1674-1137/abddae.
- ^ Cite error: The named reference
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