element 111 vs roentgenium

element 111 and roentgenium both are nouns.

Word	Noun	Adjective	Verb	Adverb
element 111	Yes	No	No	No
roentgenium	Yes	No	No	No

As nouns, element 111 and roentgenium are synonyms defined as:

element 111 and roentgenium: a radioactive transuranic element, with atomic number 111

Other synonyms of element 111 include atomic number 111, Rg.

element 111 (noun)	roentgenium (noun)
a radioactive transuranic element, with atomic number 111	a radioactive transuranic element, with atomic number 111