Iggy's Element Bonanza! Element: Sulfur Atomic Symbol: S Atomic Number: 16 Iggy: Sulfur is a yellow crystalline solid at room temperature. If something smells bad, it most likely contains some Sulfur somewhere in it! Sufur dioxide is a toxic gas that is released by volcanoes. Sulfur also burns blue, which is why Larry and Ludwig like it. Sulfur has 4 stable isotopes, S-32, S-33, S-34, and S-36.