Seaborgium is a chemical element. In the past, it has been named eka-tungsten but is now named seaborgium. It has the symbol Sg. It has the atomic number 106. Seaborgium is a radioactive element that does not exist in nature. It has to be made. The most stable isotope is Sg. Seaborgium-271 has a half-life of 2.4 minutes. 