Glossary

Silicon is a chemical element with the symbol Si and atomic number 14. It is a metalloid, meaning it has properties of both metals and nonmetals, and is the second most abundant element in Earth’s crust (after oxygen), making up about 28% by weight. Silicon plays a critical role in both nature and technology, serving as the foundation of modern electronics and materials science.

In its pure crystalline form, silicon is a hard, dark-gray, shiny solid with a metallic luster and a brittle structure similar to glass. It does not occur naturally in its pure state, but is found extensively in compounds such as silica (SiO₂) and silicates, which form the main components of sand, quartz, clay, and many rocks.

Silicon’s semiconducting properties are what make it so important in modern life. When precisely purified and doped with trace elements such as phosphorus or boron, silicon becomes the key material used in computer chips, transistors, diodes, solar cells, and microprocessors—earning it the nickname “the backbone of the digital age.” The region in California known as Silicon Valley is named after its central role in semiconductor and computer innovation.

Beyond electronics, silicon is also vital in metallurgy, construction, and chemistry. It is used in the production of alloys such as ferrosilicon, which strengthen steel and aluminum, and in the manufacture of glass, ceramics, and concrete. In polymer form, silicones (polysiloxanes) are flexible, rubber-like materials used in seals, adhesives, lubricants, medical implants, and cookware due to their stability and resistance to temperature and moisture.