硅Silicon

硅原子最外层有 4 个电子，倾向于形成 4 个共价键而不是离子。在第三周期中，硅处于金属与非金属的分界处：单质导电性介于金属和绝缘体之间，熔点（1414 °C）是第三周期元素中最高的，因为熔化需要破坏巨型共价结构中大量的 Si–Si 键。

Silicon has four outer electrons and tends to form four covalent bonds rather than ions. In period 3 it lies on the boundary between metals and non-metals: its conductivity is between that of a metal and an insulator, and its melting point (1414 °C) is the highest in the period, because melting breaks many Si–Si bonds in a giant covalent structure.

1823 年贝采利乌斯用钾还原四氟化硅，制得较纯的无定形硅并确认其为元素。英文名来自拉丁文 silex（燧石）。中文早期译作“矽”，后为避免与“锡”同音改称“硅”，台湾地区至今仍用“矽”。

In 1823 Berzelius reduced silicon tetrafluoride with potassium, obtaining fairly pure amorphous silicon and establishing it as an element. The English name comes from Latin silex, flint. Chinese first used 矽 (xī), later changed to 硅 to avoid confusion with 锡 (tin); 矽 is still used in Taiwan.

常温下硅化学性质不活泼，表面有一层致密的 SiO₂ 保护膜。它能与氟气、氢氟酸和强碱溶液反应：Si + 2NaOH + H₂O → Na₂SiO₃ + 2H₂↑。高温下能与氧气、氯气反应，分别生成 SiO₂ 和 SiCl₄。

At room temperature silicon is fairly unreactive, protected by a thin compact layer of SiO₂. It reacts with fluorine, hydrofluoric acid and strong alkali solutions: Si + 2NaOH + H₂O → Na₂SiO₃ + 2H₂↑. When heated it reacts with oxygen and chlorine to give SiO₂ and SiCl₄.

工业上在电弧炉中用焦炭还原石英砂制得粗硅：SiO₂ + 2C → Si + 2CO，再经 SiHCl₃ 等中间体提纯为电子级高纯硅，并用直拉法拉制单晶。高纯硅用于集成电路芯片和太阳能电池；硅也用于制造硅铁合金、铝硅合金和有机硅材料。

Industrially, quartz sand is reduced with coke in an electric-arc furnace to crude silicon, SiO₂ + 2C → Si + 2CO, which is purified to electronic-grade silicon via intermediates such as SiHCl₃ and grown into single crystals by the Czochralski method. High-purity silicon is used for integrated-circuit chips and solar cells; silicon is also used in ferrosilicon, aluminium–silicon alloys and silicones.