'ununtrium' definitions:
Definition of 'ununtrium'
From: WordNet
noun
Definition of 'ununtrium'
From: Elements
- Symbol: Uut
- Atomic number: 113
- Atmic weight: 284
- Ununtrium is the temporary name of a synthetic element with the temporary symbol Uut and atomic number 113. It is placed as the heaviest member of the group 13 (IIIA) elements although a sufficiently stable isotope is not known at this time that would allow chemical experiments to confirm its position. It was first detected in 2003 in the decay of element 115 and was synthesized directly in 2004. Only eight atoms of ununtrium have been observed to date. The longest-lived isotope known is 284113 with a half-life of ~500 ms.