Makemakium

Makemakium is the hypothetical chemical element with the symbol Me and atomic number 122. It is named after the dwarf planet. It is extremely radioactive and nearly all isotopes are unstable. The most stable isotope is $2$Mm which has a half-life of 3 minutes and 2.998 seconds (182.998 s). Makemakium has such a long half-life (for a period 8 element) due to the closed proton shell.