Neptunium . It is a synthetic element of the periodic table whose symbol is Np and its atomic number is 93. Fourth of the actinide family or second internal transition period of the periodic system of elements. Its name comes from the planet Neptune .
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- 1 Discovery
- 2 Physical and Chemical Properties
- 3 Obtaining
- 4 Effects of Neptunium on Health
- 5 External links
- 6 Sources
It was first discovered in 1940 by McMillan and Abelson bombarding uranium with high-speed deuterons. Isotope 237 has been found, in very small quantities, in uranium mines . It is obtained most abundantly as a by-product in the manufacture of plutonium 239. Metallic neptunium is obtained from neptunium trifluoride by reduction with barium vapor at 1.20 ° C.
Physical and chemical properties
It is obtained artificially. It is a silvery white metal, chemically similar to uranium. There are several crystalline varieties. Neptunium is a reactive element that is miscible with most elements. It occurs in various degrees of oxidation: +3, +4, +5, +6, and +7, with +5 being the one with the greatest stability.
Neptunium was the first transuranic artificial element (after uranium) of the actinide series. It was discovered by McMillan and Abelson in Berkeley, California , bombarding uranium with neutrons produced in a cyclotron.
Effects of Neptunium on Health
Possible health effects: Bone cancer.
Organ that receives the main dose: The gastrointestinal tract.
Most of the neptunium that is retained in the body is deposited in the bones. Something is also retained in the liver. A few studies report “relatively high concentrations” of neptunium in the glands of laboratory animals. No specific health effects from exposure to neptunium have been observed in humans. Roy C. Thompson, department of biology at the Battelle Pacific Northwest laboratory in Richland, USA, conducted an extensive summary of the studies related to neptunium.
This summary included Russian studies that found an increase in bone tumors in animals that received bone doses of only a few rad. Thompson concluded that “there can be little doubt” that neptunium causes bone cancer.
In 1984 , a team of German scientists reported preliminary results from a mouse experiment designed to measure the combined effect of neptunium 239 deposition in bone and decay to plutonium 239. These initial results found evidence that increased plutonium 239 (as neptunium decayed) increased the number of bone tumors compared to those expected due to exposure to neptunium alone.