unnil- Also unun-.
Certain transuranic elements.
[Latin unus, one, plus nil, nothing.]
During a long-standing dispute over what names to give to artificially synthesized transuranic elements of atomic number over 100, temporary names were assigned by the International Union of Pure and Applied Chemistry. Names used unnil- to indicate 10, plus a Latin or Greek numeral for the final digit, plus -ium indicating an element. So unnilquadium (Latin quattuor, four), was element 104, now rutherfordium; unnilhexium (Greek hex, six) was element 106, now seaborgium. The dispute has been resolved and this naming convention is now reserved for a few elements of atomic number above 110 that have not yet been given formal names; these are formed using unun- (representing 11), as in unununium for element 111, ununquadium for 114.