Roentgenium

Roentgenium:
Roentgenium is a synthetic radioactive chemical element with the symbol **Rg** and atomic number 111. It is placed as the heaviest member of the group 11 (IB) elements, although a sufficiently stable isotope has not yet been produced in a sufficient amount that would confirm this position as a heavier homologue of gold. Roentgenium/unununium was first observed in 1994 and several isotopes have been synthesized since its discovery. The most stable known isotope is 281Rg with a half-life of ~26 seconds, which decays by spontaneous fission, like many other N=170 isotones.
 * Symbol: Rg**
 * Atomic Number: 111**
 * Atomic Weight: 281**

Discovery of Roentgenium
Roentgenium was first made by research scientists at the Heavy Ion Research Laboratory in Darmstadt, Germany in 1994. The scientists bombarded nickel-64 with bismuth-209 in a heavy ion accelerator. The element is named after physicist Wilhelm Conrad Röntgen who discovered X-rays in 1895.

Chemistry:
The heavier members of this group are well known for their lack of reactivity or noble character. Silver and gold are both inert to oxygen, but are attacked by the halogens. In addition, silver is attacked by sulfur and hydrogen sulfide, highlighting its higher reactivity compared to gold. Roentgenium is expected to be even more noble than gold and can be expected to be inert to oxygen and halogens. The most-likely reaction is with fluorine to form a trifluoride, RgF3.



Oxidation states
Roentgenium is projected to be the ninth member of the 6d series of transition metals and the heaviest member of group 11 (IB) in the Periodic Table, below [|copper], [|silver] , and [|gold]. Each of the members of this group show different stable states. Copper forms a stable +2 state, while silver is predominantly found as silver(I) and gold as gold(I) or gold(III). Copper(I) and silver(II) are also relatively well-known. Roentgenium is therefore expected to predominantly form a stable +3 state. Gold also forms a somewhat stable -1 state due to relativistic effects, and roentgenium may do so as well.