Plutonium

Plutonium was synthesized in 1940 by Glenn Seaborg, Arthur Wahl, and Joseph Kennedy. They named it after Pluto (then considered the ninth planet), continuing the pattern of uranium (Uranus) and neptunium (Neptune). Seaborg reportedly joked about calling it 'plutium' but chose 'plutonium' because it sounded better. Its chemical symbol should logically have been 'Pl,' but Seaborg chose 'Pu' as a tongue-in-cheek joke (think: 'P.U.!').

Plutonium is most famous for its use in nuclear weapons — the atomic bomb dropped on Nagasaki in 1945 used plutonium-239. It is also used as fuel in some nuclear reactors and powers deep-space probes via radioisotope thermoelectric generators (the Voyager spacecraft and Mars rovers use plutonium). Plutonium is extraordinarily dangerous — inhaling even micrograms of plutonium dust can cause cancer.

Plutonium's symbol 'Pu' is a fun two-letter element in Spellement. It matches the start of words like 'put,' 'pull,' and 'push,' fitting common English patterns. Its humorous origin story makes it a memorable element for creative word building.