Ununpentium

Ununpentium is the temporary systematic name for the chemical element with atomic number 115. It is a synthetic, highly radioactive element not found in nature. Its symbol was Uup, and it has since been renamed Moscovium (Mc) by IUPAC; ununpentium remains as a historical name for the element before its official naming.

The element was first synthesized in 2003 by a collaboration of scientists at the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory in the United States. The production involved bombarding an americium-243 target with calcium-48 ions in a heavy-ion accelerator. The experiments established the existence of element 115 and led to the use of the temporary name ununpentium.

As a superheavy synthetic element, ununpentium is extremely unstable and has no known stable isotopes. All reported isotopes are radioactive with very short half-lives, and no bulk chemical properties have been measured. The element is predicted to lie in Group 15 (the pnictogens) of period 7, and relativistic effects are expected to influence its chemical behavior, potentially limiting the observation of its chemistry. The practical chemistry of ununpentium remains largely theoretical, and experimental work is challenging due to the rapid decay of its atoms.

In 2016, IUPAC approved the name Moscovium for element 115, with the symbol Mc. The name honors the Moscow region of Russia, reflecting the contribution of the Dubna–Livermore collaboration to its discovery. Today, Moscovium is studied mainly for purposes of nuclear physics and the study of the limits of the periodic table, with no applied uses.