| Share

synthetic elements

synthetic elements, in chemistry, radioactive elements that were not discovered occurring in nature but as artificially produced isotopes. They are technetium (at. no. 43), which was the first element to be synthesized, promethium (at. no. 61), astatine (at. no. 85), francium (at. no. 87), and the transuranium elements (at. no. 93 and beyond in the periodic table). Some of these elements have since been shown to exist in minute amounts in nature, usually as short-lived members of natural radioactive decay series (see radioactivity).

The synthetic elements through at. no. 100 (fermium) are created by bombarding a heavy element, such as uranium or plutonium, with neutrons or alpha particles. The synthesis of the transfermium elements (elements with at. no. 101 or greater) is accomplished by the fusion of the nuclei of two lighter elements. Elements 101 through 106 were first produced by fusing the nuclei of slightly lighter elements, such as californium, with those of light elements, such as carbon. Elements 107 through 112 were first produced by fusing the nuclei of medium-weight elements, such as bismuth or lead, with those of other medium-weight elements, such as iron, nickel, or zinc. Of the elements greater than 112 whose creation has been officially confirmed, element 114 was discovered by fusing the nuclei of plutonium and calcium, and element 116 using curium and calcium.

The transfermium elements are produced in very small quantities (one atom at a time), and identification is therefore very difficult because of half-lives ranging from minutes to milliseconds and the need to identify the products by methods other than known chemical separations. This has led to controversy over reported discoveries and over the naming of the elements. It has been predicted that one isotope of element 114—containing 114 protons and 184 neutrons—would be very stable because its nucleus would have a full complement of protons and neutrons. Termed an "island of stability," its half-life might be measured in years. However, none of the isotopes of element 114 synthesized as yet have as many as 184 neutrons, and their half-lives are still in the millisecond range (see flerovium).

The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.

More on synthetic elements from Infoplease:

  • artificial elements - artificial elements: artificial elements: see synthetic elements.
  • man-made elements - man-made elements: man-made elements: see synthetic elements.
  • ELEMENTS - The enormous variety of matter around you is made from different combinations of substances called elements. Elements are pure substances that cannot
  • roentgenium - roentgenium roentgenium, artificially produced radioactive chemical element; symbol Rg; at. no. ...
  • meitnerium - meitnerium meitnerium , artificially produced radioactive chemical element; symbol Mt; at. no. 109; ...

See more Encyclopedia articles on: Compounds and Elements

24 X 7

Private Tutor

Click Here for Details
24 x 7 Tutor Availability
Unlimited Online Tutoring
1-on-1 Tutoring