Silicon is the second element in the fourteenth column of the period table. It is classified as a member of the metalloids. Silicon is the eighth most abundant element in the universe and the second most abundant in the Earth's crust after oxygen. Silicon atoms have 14 electrons and 14 protons with 4 valence electrons in the outer shell.
Characteristics and Properties
Under standard conditions silicon is a solid. In its amorphous (random) form it looks like a brown powder. In its crystalline form it is a silvery-gray metallic looking material that is brittle and strong.
Silicon is considered a semiconductor, meaning that it has electronic conductivity between that of an insulator and a conductor. Its conductivity increases with temperature. This property makes silicon a valuable element in electronics.
With its four valence electrons, silicon can form covalent or ionic bonds either donating or sharing its four shell electrons. At the same time, it is a relatively inert element and does not react with oxygen or water in its solid form.
Where is silicon found on Earth?
Silicon makes up about 28% of the Earth's crust. It is generally not found on Earth in its free form, but is usually found in silicate minerals. These minerals account for 90% of the Earth's crust. One common compound is silicon dioxide (SiO2), which is more commonly known as silica. Silica takes on different forms including sand, flint, and quartz.
Other important silicon minerals and rocks include granite, talc, diorite, mica, clay, and asbestos. The element is also found in gems including opals, agates, and amethysts.
How is silicon used today?
Silicon is used in a variety of applications and materials. Most applications of silicon use silicate minerals. These include glass (made from sand), ceramics (made from clay), and abrasives. Silicates are also used to make Portland cement which is used to make concrete and stucco.
Silicon is also used to make synthetic compounds called silicones. Silicones are used to make lubricants, greases, rubber materials, waterproofing materials, and caulks.
Pure silicon is used in the manufacture of semiconductor chips for electronics. These chips form the brains of today's electronics including computers, televisions, video game consoles, and mobile phones.
Silicon is also used in metal alloys together with aluminum, iron, and steel.
How was it discovered?
French chemist Antoine Lavoisier was one of the first scientists to suggest that there may be a new element in the substance quartz in 1789. Later scientists continued to study quartz, but it was Swedish chemist Jons Jakob Berzelius who first isolated the element silicon and produced a sample in 1824.
Where did silicon get its name?
The name comes from the Latin word "silicus" meaning "flint." Flint is a mineral that contains silicon.
Isotopes
Silicon occurs naturally in one of three stable isotopes: silicon-28, silicon-29- and silicon-30. Around 92% of silicon is silicon-28.
Interesting Facts about Silicon
Silicon has the relatively unique property for an element in that it expands when it freezes like water.
It has a high melting point of 1,400 degrees Celsius and boils at 2,800 degrees Celsius.
The most abundant compound in the Earth's crust is silicon dioxide.
Silicon Carbide (SiC) is often used as an abrasive and is nearly as hard as diamond.
Silicon wafers for computer chips are "grown" using the Czochralski process.
