F
- PDF / 2,965,822 Bytes
- 12 Pages / 595.276 x 841.89 pts (A4) Page_size
- 57 Downloads / 147 Views
Cross-references
FERMIUM Fermium (Fm), atomic number (Z) 100, is the eleventh member of the actinide series. Eighteen isotopes (mass = 242-259) have been synthesized and observed. Fermium has no natural abundance; the half-lives range from 0.37 ms to 100.5 days. The electron configurations of the several ionic forms of this element have been determined from atomic beam experiments: M 0 (g) [Rn] 5f 12 7s 2 ; M+(g) [Rn] (5f 12 7s 1 ); M+ 2 (g) [Rn] (5f1 2 ); M+ 3 (g) [Rn] (5f 11 ); M+ 4 (g) [Rn] (5f 10 ). Predicted configurations are shown in parentheses. The crystal structure ionic radius for the + 3 ion with a coordination number of six is 0.0922 nm. Fermium was discovered in 1953 by A. Ghiorso, S.G. Thompson, G.H. Higgins, G.T. Seaborg, M.H. Studier, P.R. Fields, S.M. Fried, H. Diamond, J.F. Mech, G.L. Pyle, J.R. Huizenga, A. Hirsch, W.M. Manning, C.I. Browne, H.L. Smith, and R.W. Spence. Twenty hour 255 Fm activity emitting 7.1 MeV alpha particles was discovered in the debris from the test of a large thermonuclear device. The element is named in honor of the father of the atomic age, Enrico Fermi. Only very small quantities of elements fermium (pg) through lawrencmm (tens of atoms) are available. This is because of their_ sh~rt half-lives and difficulty in synthesizing the isotopes (ava1lab1hty of target material and facility availability). Consequently, even in nuclear waste or fallout these elements have no (and will have no) geologic ramifications. Cynthia E.A. Palmer Bibliography Firestone, R.B. ( 1996) Table of Isotopes, Volume II: A= 151-272. New York: Wiley-Interscience, 2877 pp. Ghiorso, A., Thompson, S.G.,_ Higgins, G.H. et al. (1955) New elements emstemmm and fermmm, atomic numbers 99 and 100. Phys. Rev., 99, 1048. Seaborg, G.T. and Loveland, W.D. (1990) The Elements Beyond Uranium. New York: Wiley-Interscience, 359 pp.
Elements: actinide series Radioactivity
FICK'S lAW Adolph Fick (born September 3, 1829 in Germany; died August 21, 1901 in Belgium), originator of the law, had an academic career in anatomy and physiology. Fick's talent for elucidating physiological processes in mathematical terms led him to study the role of electricity, optics and hydrodynamics in organisms. Fick's law states that the rate of transfer of molecules or atoms by diffusion through a unit area is proportional to concentration gradient. Theory Development
In the broadest sense the term diffusion refers to the process or state of dissemination and mixing. In geology the term is applied to the process by which small particles such as atoms and molecules move in gases, liquids and solids under the influence of a chemical potential gradient. The process is random (i.e. the final location of a specific particle cannot be predicted) and movement is a response to the uneven distribution of heat and pressure around the particles. In studying the random mixing produced by diffusion in gases and liquids, Fick drew an analogy to the Fourier (1822) equations for heat transfer, which involve fluxes and gradients. Fick's first law has
Data Loading...
