Traduzione e analisi delle parole tramite l'intelligenza artificiale ChatGPT
In questa pagina puoi ottenere un'analisi dettagliata di una parola o frase, prodotta utilizzando la migliore tecnologia di intelligenza artificiale fino ad oggi:
- come viene usata la parola
- frequenza di utilizzo
- è usato più spesso nel discorso orale o scritto
- opzioni di traduzione delle parole
- esempi di utilizzo (varie frasi con traduzione)
- etimologia
Cosa (chi) è neptunium$52190$ - definizione
![[[Dmitri Mendeleev]]'s table of 1871, with an empty space at the position after uranium.](https://commons.wikimedia.org/wiki/Special:FilePath/Mendelejevs periodiska system 1871.png?width=200 "[[Dmitri Mendeleev]]'s table of 1871, with an empty space at the position after uranium.")
![[[Flowchart]], showing the Purex process and the likely oxidation state of neptunium in the process solution.<ref name="Yoshida710" />](https://commons.wikimedia.org/wiki/Special:FilePath/Neptunium Purex process.png?width=200 "[[Flowchart]], showing the Purex process and the likely oxidation state of neptunium in the process solution.<ref name=\"Yoshida710\" />")
.png?width=200 "Phase diagram of neptunium")
Wikipedia
Neptunium (93Np) is usually considered an artificial element, although trace quantities are found in nature, so a standard atomic weight cannot be given. Like all trace or artificial elements, it has no stable isotopes. The first isotope to be synthesized and identified was 239Np in 1940, produced by bombarding 238
U
with neutrons to produce 239
U
, which then underwent beta decay to 239
Np
.
Trace quantities are found in nature from neutron capture reactions by uranium atoms, a fact not discovered until 1951.
Twenty-five neptunium radioisotopes have been characterized, with the most stable being 237
Np
with a half-life of 2.14 million years, 236
Np
with a half-life of 154,000 years, and 235
Np
with a half-life of 396.1 days. All of the remaining radioactive isotopes have half-lives that are less than 4.5 days, and the majority of these have half-lives that are less than 50 minutes. This element also has five meta states, with the most stable being 236m
Np
(t1/2 22.5 hours).
The isotopes of neptunium range from 219
Np
to 244
Np
, though the intermediate isotope 221
Np
has not yet been observed. The primary decay mode before the most stable isotope, 237
Np
, is electron capture (with a good deal of alpha emission), and the primary mode after is beta emission. The primary decay products before 237
Np
are isotopes of uranium and protactinium, and the primary products after are isotopes of plutonium. Uranium-237 and neptunium-239 are regarded as the leading hazardous radioisotopes in the first hour-to-week period following nuclear fallout from a nuclear detonation, with 239Np dominating "the spectrum for several days."
