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 kno... More

Atomic number:

  • 111

Periodic table block:

Chemical Element

The 111th Element in the Periodic Table

← Previous

Darmstadtium

Darmstadtium is a chemical element with the symbol Ds and atomic number 110. It is placed as the heaviest member of group 10, but no known isotope is...

Next →

Copernicium

Copernicium ( /koʊpərˈnɪsiəm/ koh-pər-NIS-ee-əm) is a chemical element with symbol Cn and atomic number 112. It is an extremely radioactive synthetic...

View collection »

Symbol:

  • Rg

Atomic mass:

  • 272 u (4.52E-16 µg )

Chemical series:

Discovery Date:

  • 1994

Discovering Country:

top ↑
Edit and Show details

Add or delete facts, download data in JSON or RDF formats, and explore topic metadata.

Freebase Logo
What is Freebase?

Freebase is a huge collection of facts, built by people like you. Freebase connects facts in ways other sites can't, giving you new ways to explore millions of subjects.
You can help improve it!