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Neptunium is a chemical element; it has symbol Np and atomic number 93. A radioactive actinide metal, neptunium is the first transuranic element. It is named after Neptune, the planet beyond Uranus in the Solar System, which uranium is named after. A neptunium atom has 93 protons and 93 electrons, of which seven are valence electrons.
Neptunium-237 and some isotopes of americium might be usable, but it is not clear that this has ever been implemented. The latter substances are part of the minor actinides in spent nuclear fuel . [ 6 ]
Francium was the last element to be discovered in nature, rather than synthesized in the lab, although four of the "synthetic" elements that were discovered later (plutonium, neptunium, astatine, and promethium) were eventually found in trace amounts in nature as well. [178]
In 1941, Glenn T. Seaborg named the newly created element plutonium after Pluto, in keeping with the tradition of naming elements after newly discovered planets, following uranium, which was named after Uranus, and neptunium, which was named after Neptune. [40] Most languages use the name "Pluto" in various transliterations.
The pits of the first nuclear weapons were solid, with an urchin neutron initiator in their center. The Gadget and Fat Man used pits made of 6.2 kg of solid hot pressed plutonium-gallium alloy (at 400 °C and 200 MPa in steel dies – 750 °F and 29,000 psi) half-spheres of 9.2 cm (3.6 in) diameter, with a 2.5 cm (1 in) internal cavity for the initiator.
A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, they are called "synthetic", "artificial", or "man-made".
This created concern within the U.S. government and military, because, unlike Mike, the Soviet device was a deliverable weapon, which the U.S. did not yet have. This first device though was arguably not a true hydrogen bomb and could only reach explosive yields in the hundreds of kilotons (never reaching the megaton range of a staged weapon).
neptunium: from Neptune (Norse equivalent is Ægir) helstuff: plutonium: from Pluto (Norse equivalent is Hel) roundaround board of the firststuffs: periodic table of elements: from Latin periodus (“complete sentence, period, circuit”), from Ancient Greek períodos (“cycle, period of time”) farer: ion