Silicon

Silicon is a fundamental chemical element with the symbol Si and atomic number 14. It is a hard, brittle, crystalline solid that displays a blue-grey metallic lustre. In the periodic table, silicon belongs to group 14, sitting directly below carbon and above germanium. It is classified as a tetravalent non-metal or a metalloid. Because it can act as a semiconductor, it is essential for modern electronics.

As a semiconductor, silicon possesses unique electronic properties that allow it to control electricity. This makes it the primary material for transistors, solar cells, and integrated circuits. Silicon is preferred for these applications because it is low in cost and highly adaptable. In the late 20th and early 21st centuries, the massive impact of silicon on the global economy led to this era being called the Silicon Age. This period is also known as the Digital Age or the Information Age.

Silicon interacts with the world in several distinct ways. In its pure form, it is relatively unreactive. However, it has a very high chemical affinity for oxygen. When silicon bonds with oxygen, it forms a family of anions known as silicates. These silicates are incredibly diverse and make up more than 90% of the Earth's crust.

Silicon also forms the basis for synthetic polymers called silicones. Additionally, compounds like silicon carbide are used as high-strength ceramics and abrasives.

The history of silicon involves many famous scientists and long periods of discovery. Ancient civilizations, including the Egyptians and the Chinese, used silicon rock crystals for beads and vases. The Egyptians also manufactured glass containing silica around 1500 BC. In 1787, Antoine Lavoisier suspected silica was an oxide of a fundamental element. In 1808, Sir Humphry Davy proposed the name "silicium" because he believed it was a metal. Later, in 1817, Thomas Thomson changed the name to "silicon." He chose this because silicon resembles the nonmetals boron and carbon.

It was not until 1823 that Jöns Jakob Berzelius successfully prepared and characterized silicon in its pure form. He achieved this by reducing potassium fluorosilicate with molten potassium metal. He produced a brown powder through repeated washing. This was a major breakthrough because silicon's high affinity for oxygen made it very difficult to isolate. In 1854, Deville later prepared silicon in its more common crystalline form.

This process involved passing silicon chloride vapors over pure aluminum to create hard, octahedral crystals.

Silicon is a massive presence in both the universe and our planet. It is the eighth most common element in the universe by mass. It is found widely in cosmic dust, planetoids, and planets as silica or silicates. On Earth, silicon is the second most abundant element in the crust, making up about 28% by mass. It is surpassed only by oxygen. Silicon is also remarkably stable at high temperatures. Its melting point is 1414 °C, and its boiling point is 3265 °C. These are the second highest points among all nonmetals and metalloids, trailing only boron.

Beyond industry, silicon plays a vital role in biology and construction. Many plant tissues contain deposited silica, which is essential for certain metabolic processes. In the ocean, microorganisms like diatoms and radiolaria, as well as some sea sponges, secrete silica to build skeletal structures.

In the built environment, silicon is everywhere. It is used in Portland cement for mortar and stucco. When mixed with sand and gravel, silicates create concrete for roads and foundations. It is also used to produce porcelain ceramics and various types of glass. The semiconductor industry itself is massive, with projections suggesting it will reach $726.73 billion by 2027.