What Is Sulfur?

Where is sulfur on the periodic table?

Sulfur has atomic number 16, the symbol S, and sits in group 16 of the periodic table alongside oxygen, selenium, tellurium, and polonium. Its atomic mass is about 32. Four stable isotopes exist (S-32, S-33, S-34, S-36), with S-32 being most common at 95%. Sulfur has been known since prehistoric times and is mentioned in some of the oldest written texts. The element is the tenth most abundant in the universe and occurs naturally as elemental sulfur in volcanic regions and in many minerals like pyrite (fool's gold), gypsum, and various sulfides.

What are the properties of sulfur?

Sulfur is a bright yellow, brittle, crystalline solid at room temperature, melting at 115°C and boiling at 445°C. The element has many allotropes, with rhombic sulfur (S₈ rings) being the most stable at room temperature. Sulfur is insoluble in water but dissolves in some organic solvents. Molten sulfur has unusual properties: it darkens and becomes viscous as temperature rises before becoming fluid again at very high temperatures. When sulfur burns in air, it produces sulfur dioxide with a characteristic choking smell and a blue flame. Density is 2.07 g/cm³.

What is sulfur used for?

About 90% of all mined sulfur becomes sulfuric acid, one of the most important industrial chemicals on Earth, used to make fertilizers, batteries, cleaners, and countless chemical products. Vulcanization treats rubber with sulfur to make it stronger and more elastic, the process that made modern tires possible. Gunpowder is partly sulfur. Fungicides and pesticides use sulfur for centuries-old applications still common in agriculture. Black gunpowder, matches, and fireworks contain sulfur. Some pharmaceuticals and skin treatments use sulfur compounds. Petroleum refineries remove sulfur from fuels to reduce air pollution.

Why is sulfur essential to life?

Sulfur is required by all living organisms as a component of the amino acids cysteine and methionine, which form proteins. The disulfide bonds between cysteine residues hold many proteins in their proper shapes, including the structures of hair and nails. Several B vitamins, including biotin and thiamine, contain sulfur. Sulfur compounds give onions, garlic, and cruciferous vegetables their distinctive flavors and many of their health benefits. The smell of cooked eggs, skunk spray, and bad breath all come from sulfur compounds. Adults need only small amounts daily, easily obtained from protein-rich foods.