"Internet nexus of cultural Judaism" — Examiner.com
While we're at it: Gregor Mendel, also Not a Jew.
Suggestions by Mila from Alexnadria, Eli from Israel, and Malcolm from Belgium.
Mendeleyev himself said his father's nickname was given to him because of the local wealthy land-owner named Mendeleyev. It was supposedly after his dad was involved in a trade, "just like the land-owner trading his horses." So the name has even more Jewish (or at least stereotypically Jewish) connotations. Not sure whether the land-owner was Jewish. If he was, it's more than likely he was converted.
Mendel is mainly "Jewish" in the US and Canada. Look at a German phonebook and you'll find Mandel, Mendel, etc. are actually quite common and I doubt most of them are Jewish......it also comes from the German (and Yiddish) word for "almond". One version of the name, Mindel, can in addition be Spanish or Arabic as with that spelling it means "apron" in both languages.
Mendel is quite, quite Jewish in Russia, too. But of course the land-owner in question could've been a Russified German, of whom in Czarist Russia there was a multitude.
Dmitry Mendeleev was 100% russian. His grandfather's was a russian priest in russian church and there was a tradition to take surnames from place where family live but Dmitry's father take surname Mendeleev from his neighbors Mendeleev as he change something to money as Mendeleevs changed their horses. So "Mendeleev" was a nickname of Dmitry's grandfather and this nickname became surname.