An artificially produced radioactive element with atomic number 105 whose many long-lived isotopes have actually size amounts of 258, 261, 262, and 263 with half-lives of 4.2, 1.8. 34, and 30 seconds, respectively. Also referred to as unnilpentium. See Dining Table at element.
A transuranic substance factor (sign Db) with atomic quantity 105.