transuranium elements

The Columbia Encyclopedia, 6th ed.

transuranium elements

transuranium elements, in chemistry, radioactive elements with atomic numbers greater than that of uranium (at. no. 92). All the transuranium elements of the actinide series were discovered as synthetic radioactive isotopes at the Univ. of California at Berkeley or at Argonne National Laboratory; in order of increasing atomic number they are neptunium, plutonium, americium, curium, berkelium, californium, einsteinium, fermium, mendelevium, nobelium, and lawrencium. Of these only neptunium and plutonium occur in nature; they are produced in minute amounts in the radioactive decay of uranium.

Much of the study of the transuranium elements has taken place at the Lawrence Berkeley National Laboratory (at Berkeley, Calif.) and at the Joint Institute for Nuclear Research in Dubna, Russia; workers at both locations share credit for the independent discovery of rutherfordium, dubnium, and seaborgium (at. no. 104, 105, and 106, respectively), which are the first three transactinide elements. A German team at the Institute for Heavy Ion Research at Darmstadt discovered bohrium, hassium, meitnerium, darmstadtium, roentgenium, and copernicium (at. no. 107 through 112). The Dubna laboratory, with assistance from Lawrence Livermore National Laboratory, Calif., has been credited with synthesizing flerovium (at. no. 114) and livermorium (at. no. 116) and claims to have produced ununtrium (at. no. 113), ununpentium (at. no. 115), and ununoctium (at. no. 118); and with assistance from Vanderbilt Univ. and the Oak Ridge National Laboratory, Tenn., to have produced ununseptium (at. no. 117). The Berkeley team claimed to have produced livermorium and ununoctium, but later retracted the claim for ununoctium after other laboratories failed to reproduce Berkeley's results and a reanalysis of their data did not show the production of the element.

Up to and including fermium (at. no. 100), the transuranium elements are produced by the capture of neutrons; the transfermium elements are synthesized by the bombardment of transuranium targets with light particles or, more recently, by projecting medium-weight elements at targets of other medium-weight elements (see also synthetic elements).

Isotopes of the transuranium elements are radioactive because their large nuclei are unstable, and the transactinide, or superheavy, elements in particular have very short half-lives. However, on the basis of theories of nuclear structure, physicists have predicted that certain transactinide elements may have relatively stable isotopes. For example, an isotope of element 114 with mass number 298 (comprising 114 protons and 184 neutrons) should be very stable and resemble lead in its chemical properties. However, the three isotopes of element 114 that are claimed to have been synthesized have fewer than the requisite 184 neutrons.

See G. T. Seaborg and W. D. Loveland, The Elements beyond Uranium (1990); L. R. Morss and J. Fuger, ed., Transuranium Elements (1992); G. T. Seaborg and A. Ghiorso, The Transuranium People (1999).

Notes for this article

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Project items

Items saved from this article

This article has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this article

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this article

Cited article

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited article

transuranium elements
Settings

Settings

Typeface
Text size Smaller Larger
Search within

Search within this article

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.