硫Sulfur

硫原子最外层有 6 个电子，可得到 2 个电子形成 S²⁻，或形成两个共价键（H₂S）。由于有可用的第三层轨道，硫还能形成 4 个或 6 个键，如 SO₂、SF₄、SO₃、SF₆、H₂SO₄，常见氧化态为 −2、+4、+6。

Sulfur has six outer electrons; it can gain two to form S²⁻ or form two covalent bonds (H₂S). With its third shell available it can also form four or six bonds, as in SO₂, SF₄, SO₃, SF₆ and H₂SO₄; common oxidation states are −2, +4 and +6.

常温稳定的是斜方硫，95.3 °C 以上转变为单斜硫，两者都由 S₈ 分子组成。硫不溶于水，易溶于二硫化碳。在空气中燃烧发出淡蓝色火焰，生成 SO₂：S + O₂ → SO₂；加热时与铁、铜等金属化合生成硫化物。

Rhombic sulfur is stable at room temperature and changes to monoclinic sulfur above 95.3 °C; both consist of S₈ molecules. Sulfur is insoluble in water but dissolves readily in carbon disulfide. It burns in air with a pale blue flame to SO₂, S + O₂ → SO₂, and combines with metals such as iron and copper on heating to form sulfides.

硫的最大用途是经接触法制硫酸。硫还用于橡胶硫化、制造火药和杀菌剂。燃烧含硫化石燃料产生的 SO₂ 是形成酸雨的主要原因之一，因此燃料需脱硫。

Most sulfur goes to make sulfuric acid by the Contact process. It is also used to vulcanise rubber and in gunpowder and fungicides. SO₂ from burning sulfur-containing fossil fuels is a major cause of acid rain, so fuels are desulfurised.