Silicon

Silicon is a chemical element with the symbol Si and atomic number 14. It is a metalloid, meaning it has properties between those of metals and nonmetals. In its crystalline form, silicon adopts a diamond cubic structure and is solid at room temperature. It is a poor conductor of electricity but becomes more conductive when doped with other elements, giving it essential semiconductor properties. Silicon has a high melting point of about 1414°C and a boiling point near 2900°C, a density of 2.33 g/cm³, and a thermal conductivity around 148 W/m·K. It forms a protective native oxide layer of silicon dioxide (SiO2 in air), which influences its surface chemistry and is central to many device fabrication processes.

Occurrences and production: Silicon is the second most abundant element in Earth’s crust by mass, comprising about 27–28% and mainly occurs as silicon dioxide in minerals such as quartz and as silicates. Pure silicon is produced by reducing silica with carbon in electric furnaces to yield metallurgical-grade silicon, which is then refined to higher purities for electronics and solar applications. High-purity silicon, often in the form of polysilicon, is used to fabricate semiconductor devices and photovoltaic cells.

Properties and applications: Silicon’s semiconducting behavior makes it the foundation of modern electronics, including integrated circuits and computer processors. It is also widely used in solar cells, where doped silicon absorbs light and generates charge carriers. Other uses include silicone polymers and silicone-based materials, as well as silicon alloys such as aluminum-silicon casting alloys. The versatility of silicon arises from its abundant supply, stable oxide, and favorable electrical properties.

History and naming: Silicon was first produced in the early 19th century and was named after silex, the Latin for flint. Its development into a key industrial material followed advances in semiconductor fabrication and materials purification.

Safety: Inhalation of crystalline silica dust can cause lung disease; many silicon compounds have varying hazards and should be handled with appropriate safety measures.