10 Facts About Silicon

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How well do you know the periodic table? Our series The Elements explores the fundamental building blocks of the observable universe—and their relevance to your life—one by one.

Silicon is a metalloid: an element with properties not quite like a metal, nor exactly like a non-metal. If you have a cell phone in your pocket or dirt on your shoes, you’re carrying silicon. Learn more about this ever-present element.

1. IT'S JUST ABOUT EVERYWHERE.

It's the seventh most abundant element in the universe and even more prevalent in the Earth's crust, second only to oxygen as the most common element by weight. The layer under the crust—the mantle—is rich in silicon as well. With an atomic number of 14, it sits right below carbon on the periodic table.

2. SILICON ISN'T THE SAME THING AS SILICONE.

silicone breast implant on blue cloth
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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. By mixing up these side groups of molecules and creating links between chains, chemists can create silicones with all sorts of different properties. 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. 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.

3. WE USED SILICON FOR THOUSANDS OF YEARS WITHOUT KNOWING ITS ELEMENTAL NATURE.

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. 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.

It took many centuries before people realized the substance could be further separated into two different elements—oxygen and silicon. 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). Silica was one of them. Perhaps, Lavoisier mused, some of the earths were really molecules of oxygen and a yet-undiscovered, metal-like element.

At the time, chemists didn’t know how to remove the oxygen atoms, which form strong bonds with the silicon atoms. 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. (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.

4. SILICA IS THE MOST COMMON FORM OF SILICON.

Also known as silicon dioxide, this molecule is composed of one silicon atom and two oxygen atoms (SiO2). Most of what we call silicon is actually silica, found in both minerals and plants. Many plants create unique microscopic structures called phytoliths using silica they take up from the soil. 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.

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. 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. And because phytoliths survive burning, “we can study how they made fire or what type of food they were consuming,” Cabanes tells Mental Floss.

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.

5. IT'S A KEY COMPONENT OF SOME BEAUTIFUL STONES …

close-up of onyx
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Gorgeous gemstones like amethyst, onyx, and agate are all made of silica. In each rock, the silica molecules are arranged in repeating 3D geometries called crystal structures. Different arrangements, as well as small impurities in the rock, give each gemstone its unique appearance.

6. … AND THE DAZZLING BEAUTY OF DIATOMS.

Triceratium polycystinorum diatom
Anatoly Mikhaltsov, Wikimedia Commons // CC BY-SA 4.0

Silica also forms the cell walls of diatoms, a type of algae found all over the world. Diatoms, which come in a mesmerizing variety of shapes, can live in both fresh and saltwater. 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.

7. SILICON IS VERY USEFUL IN TECH …

Silicon can act as a semiconductor—a material that neither conducts electricity perfectly nor insulates against it, but rather lies somewhere in between. This property is important in many parts of electronics, where you want some control over the flow of 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. 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.

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"). 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.

8. … BUT RESEARCHERS WANT TO FIND BETTER OPTIONS.

Engineers like Pop are looking for materials to replace silicon in our electronics to help keep up with the demand for faster computing. “Silicon is sort of like the Honda Civic of semiconductors,” Pop says. “It gets the job done, but it’s not very fast.” However, Pop thinks that even when pitted against superior materials, silicon won’t completely disappear, thanks to its low cost.

9. SILICON HOLDS UP MANY OF OUR BUILDINGS.

brick building against blue sky
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Many common building materials are based on silicon-containing substances. Clay minerals, which contain silicon, are used to make bricks, as well as Portland cement, which is then used as the binding agent in concrete.

10. AMERICANS LEFT A BIT OF SILICON ON THE MOON.

When Buzz Aldrin and Neil Armstrong became the first humans to walk on the Moon, in 1969, they left a few things on its surface besides their footprints. One was a small silicon disc, inscribed with messages from the leaders of 73 countries, from Afghanistan to Zambia. The disc is housed inside a protective aluminum case and is stashed in a small bag along with a few other items. Silicon was elected official message-bearer because it could endure the huge range of temperatures on the Moon. The disc nearly didn’t make it, though: Aldrin had forgotten all about the bag, tucked into a pocket of his space suit sleeve, and he was already on the ladder to the spacecraft when Armstrong reminded him about it. Aldrin tossed the pouch onto the Moon.

8 Facts About the Element Neon

Most of us are familiar with neon as a term for bright colors and vibrant signs, but you may not know as much about the element underlying the name, which scientists were first able to isolate starting in 1898. Here are eight facts about neon—abbreviated Ne and number 10 on the periodic table— that might surprise you.

1. The element neon wasn’t William Ramsay’s first big discovery.

Sir William Ramsay already had a few elements under his belt by the time he and fellow British chemist Morris Travers became the first scientists to isolate neon. In 1894, he and physicist John Williams had isolated argon from air for the first time. Then, in 1895, he became the first person to isolate helium on Earth. But he had a hunch that more noble gases might exist, and he and Travers isolated neon, krypton, and xenon for the first time in 1898. As a result of his discoveries, Ramsay won the Nobel Prize in chemistry in 1904.

2. It’s one of the noble gases.

There are seven noble gases: helium, neon, argon, krypton, xenon, radon, and oganesson (a synthetic element). Like the other noble gases, neon is colorless, odorless, tasteless, and under standard conditions, nonflammable. Neon is highly unreactive—the least reactive of any of the noble gases, in fact—and doesn’t form chemical bonds with other elements, so there are no neon compounds. That non-reactivity is what makes neon so useful in light bulbs.

3. The name means new.

With the exception of helium, all of the noble gases have names ending in -on. The word neon comes from the Greek word for new, νέος.

4. It's pulled out of the air.

Neon is one of the most abundant elements in the universe. Stars produce it, and it’s one of the components of solar wind. It's also found in the lunar atmosphere. But it’s difficult to find on Earth. Neon is located in Earth’s mantle as well as in tiny amounts in air, which is where we get commercial neon. Dry air contains just 0.0018 percent neon, compared to 20.95 percent oxygen and 78.09 percent nitrogen, plus trace amounts of other gases. Using a process of alternately compressing and expanding air, scientists can turn most of these gases into liquids, separating them for industrial and commercial use. (Liquid nitrogen, for instance, is used to freeze warts and make cold brew coffee, among other applications.) In the case of neon, it’s not a simple or efficient process. It takes 88,000 pounds of liquid air to produce 1 pound of neon.

5. It glows red.

Although we associate neon with a whole spectrum of bright, colorful lights, neon itself only glows reddish-orange. The signs we think of as just “neon” often actually contain argon, helium, xenon, or mercury vapor in some combination. On their own, these gases produce different colors—mercury glows blue, while helium glows pinkish-red and xenon glows purple. So to create a range of warm and cool colors, engineers combine the different gases or add coatings to the inside of the lighting tubes. For instance, deep blue light might be a mixture of argon and mercury, while a red sign probably has a neon-argon mixture. Depending on the color, some of the signs we call neon may not contain any neon at all. (These days, though, many bright signs are made with LEDs, rather than any of these inert gases.)

6. It quickly became a lighting element.

From the start, Ramsay and Travers knew that neon glowed if it came into contact with a high voltage of electric current. In fact, Ramsay referred to its "brilliant flame-covered light, consisting of many red, orange, and yellow lines” in his Nobel Prize lecture. Soon enough, French engineer Georges Claude began trying to harness it for use in commercial lighting. He had developed a new process to liquify air and separate its different components on an industrial scale. His company, L’Air Liquide, started out selling liquid oxygen, but Claude also figured out a way to make money off one of the byproducts of the process, neon. Inspired by the design of Moore lamps, he put neon into long glass tubes that were book-ended with electrodes. He debuted his first glowing neon tubes in Paris in 1910, and sold his first neon sign in 1912. He attained a U.S. patent for neon lighting in 1915, and went on to make a fortune.

7. It made it to California before Las Vegas.

Neon signage didn’t immediately come to Las Vegas, though it would later become an integral part of that city’s architectural aesthetic. (Vegas is now home to the Neon Museum, a collection of classic neon signs.) It’s unclear where neon signs first came to the U.S.—legend has it that Los Angeles became the first U.S. city to boast a neon sign thanks to the luxury car company Packard (which caused traffic jams when it debuted its brightly colored billboard)—but academics and historians have had trouble verifying that claim. The earliest neon sign researchers Dydia DeLyser and Paul Greenstein were able to track down in the U.S. was indeed a Packard sign in California dating back to 1923. But it hung outside a showroom in San Francisco, not Los Angeles.

8. It’s for more than just signs.

Neon is also used in lasers, electronic equipment, diving gear, and more. It’s a highly effective refrigerant, and is used to cool motors, power equipment, and superconductors, among other things.

8 Facts About Silver

Peter Macdiarmid/Getty Images
Peter Macdiarmid/Getty Images

Subtle silver gets pushed aside next to gold, but in many ways it outranks its lustrous competition. The cool-toned element is more conductive and more reflective, and boasts properties absent in other metals, like a reaction with light that put the “silver” in “silver screen.” Read on for more.

1. HUMAN USE OF SILVER DATES BACK TO 3000 BCE.

Archeological records show humans have mined and used silver (or Ag, number 47 on the periodic table) for at least 5000 years. Silver shows up in slag heaps at ancient mines in Turkey and Greece, as well as in deposits in China, Korea, Japan, and South America. Its visible shine made it popular in jewelry, decorative objects, and practical tools like the aptly named silverware. Its rarity gave it high value. Silver coins are credited with fueling the rise of classical Athens, and Vikings used “hacksilver”—chunks of silver bullion chopped off a larger block of the metal—as money.

2. SOME INDIGENOUS CULTURES WERE EXPERTS AT SILVERSMITHING.

As a soft, pliable metal, silver is easily smelted, but the process still requires moderate heat. Metal workers in the precolonial Americas didn’t have bellows to pump oxygen to a fire; instead, several people would encircle the fire and blow on it through tubes to increase its intensity. The Inca of the Andes became expert silversmiths. They believed gold was the sweat of the sun, and silver came from the tears of the moon.

3. SILVER CONDUCTS ELECTRICITY BETTER THAN ANY OTHER METAL.

Of all metals, silver is the best conductor of heat and electricity, so it can be used in a wide variety of applications. Metal solder, electrical parts, printed circuit boards, and batteries have all be made with silver. But it’s expensive: In electrical wiring, copper is often used instead.

4. ITS REACTIVITY TO LIGHT MADE EARLY PHOTOGRAPHY POSSIBLE.

In the 1720s, German physicist Johann Heinrich Schulze produced the first images with silver. Having discovered that a piece of chalk dipped in silver nitrate would turn black when exposed to sunlight, Schulze affixed stencils to a glass jar filled with a mix of chalk and silver nitrate. When he brought the jar into the sun, the light “printed” the stencil letters onto the chalk. A century later, Louis-Jacques-Mandé Daguerre created photographic prints on silver-coated copper plates. At the same time, British chemist William Henry Fox Talbot devised a method for developing an exposed image on silver iodide-coated paper with gallic acid.

“The effect was seen as magical, a devilish art. But this mystical development of an invisible picture was a simple reduction reaction,” science reporter Victoria Gill explains on the Royal Society of Chemistry’s podcast Chemistry in its Element. “Hollywood could never have existed without the chemical reaction that gave celluloid film its ability to capture the stars and bring them to the aptly dubbed silver screen.” Silver salts are still used in rendering high-quality images.

5. THAT SAME REACTIVITY CAN ALSO CAUSE TARNISH.

Silver reacts with sulfur in the air, which forms a layer of tarnish that can darken or change the color of a silver object. The tarnish interferes with how silver reflects light, often turning the object black, gray, or a mix of purple, orange, and red. An at-home experiment can demonstrate the process: Put a shelled and quartered hard-boiled egg (preferably still warm) in the same container as a silver object, like a spoon, and seal the container closed. The tarnish should appear within an hour, thanks to the egg’s release of hydrogen sulfide gas, and grow darker as time goes on.

6. RESEARCHERS ARE STILL EXPLORING SILVER’S ANTIMICROBIAL PROPERTIES.

According to a 2009 review, silver was one of the most important anti-microbial tools in use before the discovery of modern antibiotics in the 1940s. The ancient Macedonians were likely the first to apply silver plates to surgical wounds, while doctors in World War I used silver to prevent infections when suturing battlefield injuries. Silver is toxic to bacteria, but not to humans—unless it’s consumed in large quantities. Ingesting too much silver can cause argyria, a condition where the skin permanently turns gray or blue due to silver’s reactivity with light.

A 2013 study in Science Transitional Medicine looked into the mechanisms behind silver’s anti-microbial powers. The findings suggested that silver makes bacterial cells more permeable and interferes with their metabolism. When antibiotics were administered with a small amount of silver, the drugs killed between 10 and 1000 times more bacteria than without it. “It’s not so much a silver bullet; more a silver spoon to help [bacteria] take their medicine,” lead researcher James Collins, a biomedical engineer at Boston University, told Nature.

7. SILVER IODIDE HELPS MAKE IT RAIN.

When regions need rain after a prolonged drought, scientists can “seed” clouds by spraying silver iodide particles into the atmosphere. In the 1940s, Bernard Vonnegut (brother of the author Kurt Vonnegut) demonstrated in a lab that silver iodide provides a scaffold on which water molecules can freeze, which (theoretically) would lead to precipitation in the form of snowflakes. In a 2018 study, researchers from the University of Colorado in Boulder and other institutions demonstrated the process in actual clouds. The team sent out two planes; one to spray silver iodide and the other to track its course and measure how water responded. The second plane recorded a zigzagged line of water particles freezing in the same flight path as the plane spraying silver, confirming silver iodide’s role in cloud seeding.

Bernard Vonnegut had made his discovery while he and his brother both worked for General Electric in Schenectady, New York. The two discussed the idea of water stabilized as ice at room temperature—a concept that Kurt Vonnegut went on to explore as ice-nine in his novel Cat’s Cradle.

8. SILVER IS RESPONSIBLE FOR A LOT OF GHOST TOWNS.

The United States established a “bimetallic” currency during George Washington’s presidency. The policy required the federal government to purchase millions of ounces of silver each year to mint coins or set the value of paper currency. Government demand for silver contributed to the boom of Western mining towns in the mid-19th century, encouraged by the 1890 Sherman Silver Purchase Act, which increased the federal purchase of silver.

But falling values in relation to gold eventually led to the repeal of the Sherman act, and the price of silver crashed. The mining settlements shrank from hundreds of residents to just a handful—and some were completely abandoned. Ghost towns (or minimally populated near-ghost towns) with names like Bullionville, El Dorado, Potosi, and Midas can still can be explored in Nevada, the Silver State.

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