Question: what are the most dangerous elements on the periodic table?
Answer: Polonium is One Nasty Element. Polonium isn't much worse than any other radioactive element, until it gets inside your body!. ...  Mercury is Deadly and Omnipresent. ...  Arsenic is a Classic Poison. ...  Francium is Dangerously Reactive. ...  Lead is the Poison We Live With. ...  Plutonium is a Radioactive Heavy Metal.