Roentgenium (symbol Rg, atomic number 111) is a synthetic superheavy element named after Wilhelm Röntgen. It is classified as a transition metal and sits in group 11, period 7 of the periodic table.
Overview
Roentgenium is the chemical element with atomic number 111 and the symbol Rg. With a standard atomic weight of [282], it is a transition metal. In the periodic table it occupies group 11 and period 7, and under standard conditions it is normally a solid. Roentgenium is a synthetic superheavy element named after Wilhelm Röntgen.
Atomic structure
An atom of Roentgenium has 111 protons in its nucleus and, when neutral, 111 electrons arranged in the configuration [Rn] 5f14 6d9 7s2. Roentgenium has no stable isotope; the value [282] refers to the mass number of its most stable or most commonly produced isotope.
Discovery and place in the table
Roentgenium was discovered in 1994 by Gesellschaft für Schwerionenforschung. It follows Darmstadtium (Ds) and precedes Copernicium (Cn) in order of atomic number.
| Atomic number | 111 |
|---|---|
| Symbol | Rg |
| Atomic mass | [282] |
| Category | Transition metal |
| Group | 11 |
| Period | 7 |
| Electron configuration | [Rn] 5f14 6d9 7s2 |
| Phase at STP | Solid |
| Discovered | 1994 (Gesellschaft für Schwerionenforschung) |