It's cheap, it’s everywhere, and because it likes to oxidize so much, it can conveniently create its own insulating layer when exposed to air. Other materials, including germanium or gallium arsenide, are better semiconductors than silicon, but silicon is the most popular choice among electronics manufacturers (whose concentration south of San Francisco in the 1970s inspired the name "Silicon Valley"). Pure silicon is an insulator, but if you ‘dope’ it with tiny amounts of certain other elements, such as phosphorus or arsenic, it becomes better at conducting electricity. “What's beautiful about semiconductors is that you can tune their conductivity by adding impurities,” Eric Pop, a professor of electrical engineering at Stanford University, tells Mental Floss. This property is important in many parts of electronics, where you want some control over the flow of electricity. Silicon can act as a semiconductor-a material that neither conducts electricity perfectly nor insulates against it, but rather lies somewhere in between. When they die, their cell walls can accumulate into chalky deposits of "diatomaceous earth," which we use in all sorts of things, from cat litter to toothpaste. Diatoms, which come in a mesmerizing variety of shapes, can live in both fresh and saltwater. Silica also forms the cell walls of diatoms, a type of algae found all over the world. IT'S A KEY COMPONENT OF SOME BEAUTIFUL STONES …Īnatoly Mikhaltsov, Wikimedia Commons // CC BY-SA 4.0 The picture isn’t always perfect, though, because sometimes two different plants make phytoliths of the same shape-and some plants don’t make them at all. And because phytoliths survive burning, “we can study how they made fire or what type of food they were consuming,” Cabanes tells Mental Floss. Dan Cabanes, a phytolith expert and anthropologist at Rutgers University, has used phytoliths to understand how Neanderthals made a home in a cave in northern Spain, creating a sleeping area with grass bedding they used repeatedly. Phytoliths stick around long after a plant decays, which can illuminate the deep history of an area-whether it used to be a forest or grassland, for instance, or how people used the landscape. Scientists aren't sure why: They might offer protection against microscopic harm or provide structural support, or maybe they're just a way for a plant to use up extra silica. Many plants create unique microscopic structures called phytoliths using silica they take up from the soil. Most of what we call silicon is actually silica, found in both minerals and plants. SILICA IS THE MOST COMMON FORM OF SILICON.Īlso known as silicon dioxide, this molecule is composed of one silicon atom and two oxygen atoms (SiO2). (Which one, and how he did it, isn't clear.) Berzelius's breakthrough came too late for Lavoisier, who had died in 1794, to see his speculations be proven true. That changed in the 1820s, when a Swedish chemist named Jons Berzelius finally managed to obtain silicon in his lab by purifying it from a silicon-containing compound. Perhaps, Lavoisier mused, some of the earths were really molecules of oxygen and a yet-undiscovered, metal-like element.Īt the time, chemists didn’t know how to remove the oxygen atoms, which form strong bonds with the silicon atoms. In the late 1700s, French chemist Antoine Lavoisier noticed that certain materials classified as “earth” substances (which were dry and cold) sometimes behaved like metals (hard, dense, and resistant to being stretched, among other qualities). It took many centuries before people realized the substance could be further separated into two different elements-oxygen and silicon. In China, the Qin and Han dynasties used purple and blue pigments made of barium copper silicates for various decorations, including parts of the famous terra-cotta army. Silica is the main ingredient of glass, which humans have been making at least since the Egyptians fashioned beads from the material in 2500 BCE. WE USED SILICON FOR THOUSANDS OF YEARS WITHOUT KNOWING ITS ELEMENTAL NATURE. We can also thank silicones for Silly Putty, which was invented during World War II, when scientists were trying to create an alternative to rubber-and instead came up with a new national favorite toy. Yes, you can find silicones in breast implants, but also in car polish, the insulation around electric cables, and even in your hair conditioner, where they help to calm down frizz. By mixing up these side groups of molecules and creating links between chains, chemists can create silicones with all sorts of different properties. The word silicone might make you think of breast implants, but it's actually a general term for a group of synthetic substances made of alternating silicon and oxygen atoms, with carbon and hydrogen molecules bonded on the sides.
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