Allegedly "pentel" is a synonym for "pnictogen," that is, an element of group 15, the nitrogen group. However, I have not been able to find any sources to support the existence of this sense of the word except Wikipedia, Wiktionary, Wikidoc, and these two pages at thoughtco.com by Anne Marie Helmenstine, Ph.D. No other dictionary I've consulted has it, not even the OED. They only mention "pentel" as a certain kind of pen. Helmenstine's article cites
Modern Chemistry (South Carolina). Holt, Rinehart and Winston. Harcourt Education (2009)
but this citation is for the whole article, not specifically for "pentel."
So is this real, or is it a case of citogensis?