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Californium

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Californium
Californium
General Info
Atomic Symbol Atomic symbol::Cf
Atomic Number Atomic number::98
Atomic Weight Atomic weight::251.0 g/mol
Chemical series Actinide
Appearance silvery metal
Californium 2.jpg
Group, Period, Block none, 7, f-block
Electron configuration [Rn] 5f10 7s2
Electrons per shell 2,8,18,32,28,8,2
Electron shell californium.png
CAS number CAS number::7440-71-3
Physical properties
Phase Solid Metal
Density Density::15.1 g/ml
Melting point Melting point::1173 K
Boiling point Boiling point::1745 K
Isotopes of Californium
iso NA half-life DT DE (MeV) DP
is stable with neutrons.
All properties are for STP unless otherwise stated.

Californium is an artificially made chemical element that is classified as a transitional metal and an actinide. There are only a few uses due to the fact that it is radioactive. There are a few lethal military uses that correlates with the health risks if exposed to Californium without medical supervision and is only produced by the government and sold by the government. The name Californium is originated from where the element was created, the State of California at University of California, Berkeley.

Properties

Californium (symbol Cf) is a silvery white Actinide [1] rare earth [2] metal that is artificially made and radioactive [1]. It is malleable and can be easily cut with a razor blade. It has an atomic weight of 251.0 [3], atomic number 98 [2] , melting point 1173 K (900 oC), and a boiling point 1745 K (1472 oC). Californium is chemically reactive and exists in three different crystalline modifications. Its properties are similar to lanthanum's. The half lives of Californium's twenty isotopes range anywhere from forty seconds (Californium-239) to 900 years (Californium-251) [3]. Californium-252 is a very strong neutron emitter, for example, just one microgram emits 170 million neutrons per minute [1]. Californium slowly tarnishes when exposed to air at room temperature and even faster when moisture is added [3].


Occurrences

The 60-inch-diameter (1,500 mm) cyclotron used to first synthesize californium

Californium is artificially made [1] thus it is not found in the Earth's crust [4]. The way to identify the presence of californium, along with other elements, is an ion-exchange chromatography [3]. Chromatography is a range of methods used to separate and analyze complex mixtures. The elements to be separated can be distributed through two phases, stationary phase and mobile phase [5].

Compounds that Californium can form and their colors are; CfBr2-yellow, CfI2-dark violet, Cf2O3-yellowish green, CfF3-bright green, CfCl3-emerald green, CfI3-lemon yellow, CfO2-black brown, and CfF4-green [3]. Other compounds that Californium is in are; Californium trifluoride, Californium tetrafluoride, Californium dichloride, Californium trichloride, Californium tribromide, Californium diiodide, Californium triiodide, Californium dioxide, Dicalifornium trioxide [2], and californium oxychloride [6]

Uses

This is only an illustration, not californium itself. The strong α and neutron emitter produces a considerable heat.

Californium can be used in neutron moisture gauges, which are used to find water and oil bearing layers in oil wells [7] and also in soil. Knowing the amount of moisture in the soil has a great impact on construction companies and road builders [8]. It can also be used for providing neutrons for the start up of nuclear reactors, a neutron emitter. Californium-252 is used to help treat cervical cancer [4].Californium can be used as a neutron source for neutron activation. Neutron activation is where it is used to identify silver and gold ores [7]. Californium-252 (the easiest isotope to produce with a half life of 2.6 years) is obtained in gram quantities in nuclear reactors. It decays a little by spontaneous fission. This has been very useful for the study of fission, influence on the development of counters, electronic systems, and in medical research [3]. An example for electronic systems would be, the fact that Californium-252 is able to be used to inspect airline luggage without needing to be opened. For medical research, Californium may be injected into the body where then it is deposited into the bones. The radiation given off determines the health of the bone. Californium can also be used to treat ovarian and cervical cancer [8].

There are also potential military uses. "The isotope 251Cf is well-known for its small critical mass, high lethality, and short period of toxic environmental irradiation relative to other radioactive elements used for radiation explosive weaponry." These properties brought up the idea of the possible use of californium in pocket nukes. This is unlikely because it would be very difficult to make a 251Cf bomb weighing less than 2 kilograms. Not to mention the cost of such a bomb would be prohibitive. "Other weaponry uses, such as showering an area with californium, are not impossible but are considered inhumane and are subject to conditions such as inclement weather and porous terrain" [6].

Today, Californium is made only in milligrams amounts. It is produced by the government in the High Flux Isotope Radiator at the Oak Ridge National Laboratory in Tennessee and is sold by the government for $10 per millionth of a gram [8].

History

The element Californium was not only named after the State of California, but also the University of California. The element was first produced by Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street Jr., and Albert Ghiorso. While working at the University of California in 1950[7], by bombarding curium-242 with alpha particles in a 60 inch cyclotron. This created nuclear reactions that produced californium-245 (half-life 44 minutes) and a neutron. There were enough atoms to make a cube with sides about 27 nanometers long and chemical analysis proved that a new element had been made. It "was the sixth synthetic transuranium element of the actinide series to be discovered". It was not until 1958 that Burris Cunningham and Stanley Thomson isolated Californium in macro quantities for the first time [4].

Health Risks

Since Californium is so radioactive, if exposed, one can acquire cancer [1]. As the atoms of Californium decay, "they throw off energy and particles that damage or kill the cell. The damaged cells rapidly divide, producing masses called tumors. Cancerous cells can crowd out healthy cells, reduce or stop organ function, and break free to spread through the body" [8].

References

  1. 1.0 1.1 1.2 1.3 1.4 Author unknown. Californium Human Health Fact Sheet, August 2005 Web. 2005.
  2. 2.0 2.1 2.2 Author unknown. Californium Web Elements Web. Date accessed 1 November 2011.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 Author unknown.Californium Answers.com. Web. Accessed 30 October 2011.
  4. 4.0 4.1 4.2 Author-last, First. Californium Element Facts. Chemicool. Accessed 1 November 2011.
  5. Author unknown. Chromatography Chromatography. Web. 1994.
  6. 6.0 6.1 Author unknown. Californium New World Encyclopedia. Web. Date accessed 17 November 2011.
  7. 7.0 7.1 7.2 Author Unknown. It's Elemental. Jefferson Lab. Web. Accessed 30 October 2011.
  8. 8.0 8.1 8.2 8.3 Californium Chemistry Explained. Web. Date accessed 17 November 2011. Author unknown.