promethium vs atomic number 61

promethium and atomic number 61 both are nouns.

Word	Noun	Adjective	Verb	Adverb
promethium	Yes	No	No	No
atomic number 61	Yes	No	No	No

As nouns, promethium and atomic number 61 are synonyms defined as:

promethium and atomic number 61: a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium

Other synonyms of promethium include Pm.

promethium (noun)	atomic number 61 (noun)
a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium	a soft silvery metallic element of the rare earth group having no stable isotope; was discovered in radioactive form as a fission product of uranium