Fermium Notable Characteristics History Isotopes References

Home > Fermium

einsteinium – fermium – mendelevium
Er Fm
	Full table

Known properties

Name, Symbol, Number

Fermium, Fm, 100

Chemical series

Actinides

Period, Block

7, f

Appearance

unknown; probably metallic,
silvery white or gray

Atomic weight

1 E-25 kg|[257] amu]]

Electron configurationElectron configuration is the arrangement of electrons in an atom, molecule or other body. Specifically, it is the placement of electrons into atomic, molecular, or other forms of electron orbitals. Orbitals, states, and wavefunctions Since electrons are

[ RnAstatine Radon Xe Rn Uuo Full table General Name, Symbol, NumberRadon, Rn, 86 Chemical series Noble gases Group, Period, Block 18 (VIIIA), 6 , p Density, Hardness 9. 73 kg/m3 (273 K), NA Appearance colorless Atomic properties Atomic weight [222] amu Atomi]5f¹² 7 s²

e^-The electron (also called negatron commonly represented as e&minus is a subatomic particle. In an atom the electrons surround the nucleus of protons and neutrons in an electron configuration. Electrons have the smallest electrical charge and when they mov's per energy levelAn energy level is a quantified stable energy, which a physical system can have; the term is most commonly used in reference to the electron configuration of electrons, in atoms or molecules. According to quantum theory, only certain energy levels are pos

2, 8, 18, 32, 30, 8, 2

State of matter

Presumably a solid

Most stable isotopes

isoIsotopes are atoms of a chemical element whose nuclei have the same atomic number, Z but different atomic weights, A''. The word isotope meaning at the same place comes from the fact that isotopes are located at the same place on the periodic table. The a	NANatural abundance refers to the prevalence of different isotopes of an element as found in nature. The weighted (by natural abundance) average mass of these isotopes is the atomic weight listed for the element in the periodic table. The abundance of an el	half-life	DM	DE M eV	DP
²⁵²Fm	{syn.}	25.39 h	SF α	7.153	²⁴⁸ Cf
²⁵³Fm	{syn.}	3 d	ε α	0.333 7.197	²⁵³ Es ²⁴⁹Cf
²⁵⁵Fm	{syn.}	20.07 h	SF α	7.241	²⁵¹Cf
²⁵⁷Fm	{syn.}	100.5 d	α SF	6.864	²⁵³Cf

Fermium is a synthetic element in the periodic table that has the symbol Fm and atomic number 100. A highly radioactive metallic transuranic element of the actinide series, fermium is made by bombarding plutonium with neutrons and is named after nuclear physicist Enrico Fermi.

1 Notable characteristics

Only small amounts of fermium have ever been produced or isolated. Thus relatively little is known about its chemical properties. Only the (III) oxidation state of the element appears to exist in aqueous solution. Fermium-254 and heavier isotopes can be synthesized by intense neutron bombardment of lighter elements (especially uranium and plutonium). During this, successive neutron capture s mixed with beta decays build the fermium isotope. The intense neutron bombardment conditions needed to create fermium exist in thermonuclear explosion s and can be replicated in the laboratory (such as in the High Flux Isotope Reactor at Oak Ridge National Laboratory). The synthesis of element 102 ( nobelium) was confirmed when fermium-250 was chemically identified. There are no known uses of fermium outside of basic research. Fermium is the eighth transuranic element.

2 History

Fermium (after Enrico Fermi) was first discovered by a team led by Albert Ghiorso in 1952. The team found fermium-255 in the debris of the first hydrogen-bomb explosion (see Operation Ivy). That isotope was created when uranium-238 combined with 17 neutrons in the intense temperature and pressure of the explosion (eight beta decays also occurred to create the element). The work was overseen by the University of California Radiation Laboratory, Argonne National Laboratory, and Los Alamos Scientific Laboratory.

All these findings were kept secret until 1955 due to Cold War tensions, however. In late 1953 and early 1954 a team from the Nobel Institute of Physics in Stockholm bombarded a uranium-238 target with oxygen-16 ions, producing an alpha-emitter with an atomic weight of ~250 and with 100 protons (in other words, element 100-250). The Noble team did not claim discovery but the isotope they produced was later positively identified as fermium-250.

3 Isotopes

17 radioisotopes of fermium have been characterized, with the most stable being Fm-257 with a half-life of 100.5 days, Fm-253 with a half-life of 3 days, Fm-252 with a half-life of 25.39 hours, and Fm-255 with a half-life of 20.07 hours. All of the remaining radioactive isotopes have half-lifes that are less than 5.4 hours, and the majority of these have half lifes that are less than 3 minutes. This element also has 1 meta state, Fm-250m (t_½ 1.8 seconds). The isotopes of fermium range in atomic weight from 242.073 amu (Fm-242) to 259.101 amu (Fm-259).

4 References

Los Alamos National Laboratory - Fermium
Guide to the Elements - Revised Edition, Albert Stwertka, (Oxford University Press; 1998) BooksEnthsiast.com
It's Elemental -Fermium

5 External links

Chemical elements Actinides

<Hide>