Science / Periodic Table of Elements / Ununtrium (Uut): Atomic number: 113, Atomic mass: unknown, Electronegativity acoording to Pauling: unknown, Density: unknown, Melting point: unknown, Boiling point: unknown, Vanderwaals radius: unknown, Ionic radius: unknown, Isotopes: unknown, Discovered: Scientists from the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory in California in 2003. Ununtrium is the temporary name of a chemical element in the periodic table that has the temporary symbol Uut and has the atomic number 113. It was discovered from the bombardment of atoms of Americium-243 with ions of calcium-48. Among the product of the bombardment were four atoms of ununpentium which in less than 1/10 second decayed into atoms of ununtritium. On September 2004 a team of Japanese scientists declared that they succeeded in synthesizing the element. It is expected to have properties similar of thallium and indium.