Polonium poisoning of Ukrainian president (Yushchenko reference)

Used at the polonium entry in the practical-nobility table. Tom dates it "two or three years ago" (lecture is 2014; he is likely conflating the 2004 Yushchenko dioxin poisoning with the 2006 Litvinenko polonium poisoning — Tom's apparent factual error preserved per convention; flagged for footnote).

There's also what they call practical nobility. Thermodynamic nobility means it just doesn't want to form an oxide or a sulfide — it's not going to react with a lot of things. Gold is the best; iridium and platinum are near the top. Most of you don't know rhodium and ruthenium and palladium, but those are platinum group metals. Mercury is oxidation resistant; silver too. Mercury actually does react with sulfur very strongly. Osmium is another platinum group. Selenium is sort of a near metal underneath sulfur. Tellurium underneath selenium. Polonium, which is only something you poison officials in Ukraine with.