neptunium

American  

[nep-too-nee-uhm, -tyoo-] / nɛpˈtu ni əm, -ˈtyu- /

noun

Chemistry, Physics.

1. a transuranic element produced in nuclear reactors by the neutron bombardment of U-238: decays rapidly to plutonium and then to U-235. Np; 93.

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neptunium British  

/ nɛpˈtjuːnɪəm /

noun

1. a silvery metallic transuranic element synthesized in the production of plutonium and occurring in trace amounts in uranium ores. Symbol: Np; atomic no: 93; half-life of most stable isotope, ²³⁷ Np: 2.14 × 10 ⁶ years; valency: 3, 4, 5, or 6; relative density: 20.25; melting pt: 639±1°C; boiling pt: 3902°C (est)

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neptunium Scientific  

/ nĕp-to̅o̅′nē-əm /

1. A silvery, radioactive metallic element of the actinide series. It occurs naturally in minute amounts in uranium ores and is produced artificially as a byproduct of plutonium production. Its longest-lived isotope is Np 237 with a half-life of 2.1 million years. Atomic number 93.

2. See Periodic Table

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Etymology

Origin of neptunium

First recorded in 1940–45; Neptune + -ium

Example Sentences

The neptunium series, previously thought to terminate with bismuth-209, terminates with thallium-205.

From Textbooks • Feb. 14, 2019

The neptunium series is a fourth series, which is no longer significant on the earth because of the short half-lives of the species involved.

From Textbooks • Feb. 14, 2019

Once the neptunium pellets are made there, some will be sent to the Idaho lab, whose Advanced Test Reactor will help out by doing some of the irradiation.

From Nature • Nov. 24, 2014

The next planet out is Neptune, hence element 93 became neptunium - and logically element 94 became plutonium, after what was then believed to be the final planet in the solar system.

From BBC • Sep. 19, 2014

The California scientists called the newly discovered element neptunium, because it lies beyond the element uranium just as the planet Neptune lies beyond Uranus.

From A Brief History of Element Discovery, Synthesis, and Analysis by Watson, Glen W.