Science, Tech, Math › Science Oganesson Facts: Element 118 or Og Chemical & Physical Properties Share Flipboard Email Print Jose A. Bernat Bacete / Getty Images Science Chemistry Periodic Table Basics Chemical Laws Molecules Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated August 13, 2018 Oganesson is element number 118 on the periodic table. It is a radioactive synthetic transactinide element, officially recognized in 2016. Since 2005, only 4 atoms of oganesson have been produced, so there is much to learn about this new element. Predictions based on its electron configuration indicate it may be much more reactive than other elements in the noble gas group. Unlike the other noble gases, element 118 is expected to be electropositive and form compounds with other atoms. Properties of Oganesson Element Name: Oganesson [formely ununoctium or eka-radon] Symbol: Og Atomic Number: 118 Atomic Weight:  Phase: probably a gas Element Classification: The phase of element 118 is unknown. While it's possibly a semiconducting noble gas, most scientists predict the element will be a liquid or solid at room temperature. If the element is a gas, it would be the densest gaseous element, even if it is monatomic like the other gases in the group. Oganesson is expected to be more reactive than radon. Element Group: group 18, p block (only synthetic element in group 18) Name Origin: The name oganesson honors the nuclear physicist Yuri Oganessian, a key player in the discovery of the heavy new elements of the periodic table. The -on ending of the element name is in keeping with the element's position in the noble gas period. Discovery: October 9, 2006, researchers at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia, announced they had indirectly detected a ununoctium-294 from collisions of californium-249 atoms and calcium-48 ions. The initial experiments that produced element 118 took place in 2002. Electron Configuration: [Rn] 5f14 6d10 7s2 7p6 (based on radon) Density: 4.9–5.1 g/cm3 (predicted as a liquid at its melting point) Toxicity: Element 118 has no known nor expected biological role in any organism. It's expected to be toxic due to its radioactivity.