Promethium

Promethium, originally prometheum, is a chemical element with the symbol Pm and atomic number 61. All of its isotopes are radioactive; it is one of only two such elements that are followed in the periodic table by elements with stable forms, a distinction shared with technetium. Chemically, promethium is a lanthanide, which forms salts when combined with other elements. Promethium shows only one stable oxidation state of +3; however, a few +2 compounds may exist.

In 1902, Bohuslav Brauner suggested there was an element with properties intermediate between those of the known elements neodymium (60) and samarium (62); this was confirmed in 1914 by Henry Moseley who, having measured the atomic numbers of all the elements then known, found there was no element with atomic number 61. In 1926, an Italian and an American group claimed to have isolated a sample of element 61; both "discoveries" were soon proven to be false. In 1938, during a nuclear experiment conducted at Ohio State University, a few radioactive nuclides were produced that certainly were not radioisotopes of neodymium or samarium, but there was a lack of chemical proof that element 61 was produced, and the discovery was not generally recognized. Promethium was first produced and characterized at Oak Ridge National Laboratory in 1945 by the separation and analysis of the fission products of uranium fuel irradiated in a graphite reactor. The discoverers proposed the name "prometheum" (the spelling was subsequently changed), derived from Prometheus, the Titan in Greek mythology who stole fire from Mount Olympus and brought it down to humans, to symbolize "both the daring and the possible misuse of mankind's intellect." However, a sample of the metal was made only in 1963.

Features of the Marvel Universe

The comic book stories published by Marvel Comics since the 1940s have featured several noteworthy concepts besides its fictional characters, such as unique places and artifacts. The following lists detail many of them.

Places

Certain places feature prominently in the Marvel Universe, some real-life, others fictional and unique to the setting; fictional places may appear in conjunction with, or even within, real- world locales. A majority of dystopian cities have been used for their characters since the creation of Marvel Comics in the Marvel Universe.

New York City

Most of the action of Marvel Comics takes place in New York City.

New York is the site of many places important to superheroes:

  • Avengers Mansion – currently in ruin, but long the home of the Avengers.
  • Baxter Building and Four Freedoms Plaza – fictional buildings that have, at one time or another, been the home of the Fantastic Four.
  • Daily Bugle – fictional newspaper building where Peter Parker (Spider-Man) works as a photographer for J. Jonah Jameson.
  • Promethium (disambiguation)

    Promethium may refer to:

  • Promethium, the chemical element
  • A fictional petroleum-based fossil fuel as well as a refined napalm-like substance in Warhammer 40,000
  • Promethium, the name of the Mechanic Empire's queen in the fictional universe of Leiji Matsumoto

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