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 plutonium began as a different element entirely, neptunium, which scientists irradiated with neutrons in a nuclear reactor for nearly two months to convert it to the plutonium form needed for the MMRTG.

From Scientific American

The DOE reported in 2017 that trace amounts of radioactive neptunium were detected on school grounds.

From Washington Times

According to their letter, both enriched uranium and neptunium are "contaminants of concern" at the nearby Portsmouth Gaseous Diffusion Plant.

From BBC

A recent independent study conducted by Northern Arizona University found enriched uranium inside the property as well as plutonium, uranium and neptunium in water and dust samples collected from the surrounding community.

From Fox News

The DOE reported in 2017 that trace amounts of radioactive neptunium were detected in an air monitoring station on school grounds.

From Washington Post