Roentgenium - chemistry.

Roentgenium - chemistry. Roentgenium, symbol Rg, chemical element with atomic number 111. It is produced artificially by nuclear fusion (in which a chemical element with larger atoms is produced by fusing together smaller atoms from other elements). Each roentgenium atom has a very large nucleus, or central mass, containing positively charged particles called protons and neutral particles called neutrons (see Atom). The large number of particles in the nucleus makes the atom unstable and causes the atom to split apart into smaller components soon after it is created. Scientists named roentgenium in honor of German physicist Wilhelm Conrad Roentgen, the discoverer of X rays. The element was first discovered in 1994 by scientists at the Heavy-Ion Research Laboratory in Darmstadt, Germany. Roentgenium has the atomic number 111, which means that each Rg atom contains 111 protons in the nucleus. Scientists at the Heavy-Ion Research Laboratory created an atom of roentgenium that contained 161 neutrons, labeled roentgenium-272 (111 protons + 161 neutrons = roentgenium-272). Roentgenium was created by nuclear fusion of the smaller elements bismuth (Bi) and nickel (Ni). Because the roentgenium nucleus contains so many particles, the element is unstable and undergoes spontaneous fission, a process in which the atom breaks into smaller "daughter" components. When the atom splits, it releases energy in the form of electromagnetic waves and electrically charged bits of matter. This energy is known as radiation (see Radioactivity). Roentgenium-272 has a very brief lifespan that is 0.003 seconds. By 1998 roentgenium-272 was the element's only confirmed isotope. Other isotopes of roentgenium would be forms of the element with the same number of protons in the nucleus, but a different number of neutrons. Roentgenium belongs to Group 11 (Ib) on the periodic table, which also contains the naturally occurring elements copper (Cu), silver (Ag), and gold (Au). Copper, silver, and gold all have the ability to conduct heat and electricity, and to form alloys with other metals. Because elements in the same group, or column, on the periodic table often share similar properties (a pattern known as the periodic law), scientists expect roentgenium to share properties with other Group 11 elements. However, because of the very limited amount of roentgenium that has been produced and its extremely short lifespan, scientists have been unable to determine chemical properties of this unstable element. Microsoft ® Encarta ® 2009. © 1993-2008 Microsoft Corporation. All rights reserved.