Chemistry facts and facts about chemistries.
129 facts on this shelf
Sulfur dioxide is a colorless gas with a suffocating, choking odor. It is toxic to humans and concentrations as low as 8 ppm will produce coughing. Incredibly, in the Odyssey, Homer describes the burning of sulfur (formation of SO2) as a way that homes were 'fumigated'.
Russian chemist Dmitri Mendeleev published his periodic table in 1869. He left gaps for elements that had not been discovered yet and correctly predicted their properties.
Hydrogen is the most abundant element in the universe, making up about 75% of all normal matter by mass.
Hydrogen is the lightest element, with an atomic number of 1. Its most common form is just one proton and one electron.
Hydrogen was named by French chemist Antoine Lavoisier, and its name means "water-former" because burning it produces water.
English scientist Henry Cavendish identified hydrogen as a distinct element in 1766, calling it "inflammable air."
The Hindenburg airship was filled with flammable hydrogen gas, which is why it was destroyed so quickly by fire in 1937.
The Sun fuses about 600 million tons of hydrogen into helium every second.
Hydrogen fuel cell vehicles combine hydrogen with oxygen to make electricity, and their only tailpipe emission is water.
Scientists think the intense pressure inside Jupiter squeezes hydrogen into a liquid metal that can conduct electricity.
Hydrogen has three isotopes: protium, deuterium, and tritium. Radioactive tritium is used in some self-glowing exit signs.
Hydrogen bonds between water molecules give water many of its unusual properties, like its high boiling point and the way ice floats.
Helium was discovered in the Sun's light in 1868, decades before it was found on Earth.
Helium is named after Helios, the Greek god of the Sun.
Helium is the second most abundant element in the universe, but it's rare on Earth because it's so light that it escapes the atmosphere into space.
Helium makes your voice sound high and squeaky because sound travels faster through helium than through air, which changes the resonance of your vocal tract.
When cooled close to absolute zero, liquid helium becomes a superfluid that flows without friction and can creep up the walls of its container.
Liquid helium is used to cool the superconducting magnets in MRI machines.
Helium is the only element that won't freeze at normal pressure, even at absolute zero.
Helium on Earth is made by the radioactive decay of elements underground and is collected from natural gas wells. It was first found in US natural gas in Kansas in 1905.
The US government's Federal Helium Reserve near Amarillo, Texas, was sold to a private company in 2024.
Helium is a noble gas, which means it almost never reacts with other elements.
Diamonds and graphite, the "lead" in pencils, are both made entirely of carbon. The only difference is how their atoms are arranged.
Pencil "lead" doesn't contain any lead. It's made of graphite, a form of carbon, mixed with clay.
Scientists Andre Geim and Konstantin Novoselov isolated graphene, a single layer of carbon atoms, using Scotch tape in 2004 and won the 2010 Nobel Prize in Physics.
Carbon-14 dating estimates the age of once-living things by measuring how much radioactive carbon-14 is left. Its half-life is about 5,730 years.
Carbon forms more compounds than any other element, so many that a whole field, organic chemistry, is devoted to studying them.
Buckminsterfullerene, or "buckyballs," are soccer ball-shaped molecules of 60 carbon atoms discovered in 1985, which earned a Nobel Prize in 1996.
About 18% of the human body's mass is carbon.
Most natural diamonds form about 100 miles below Earth's surface under extreme heat and pressure.
The word "carbon" comes from the Latin "carbo," meaning charcoal.
Diamond is the hardest natural material, ranking 10 on the Mohs hardness scale.
About 78% of the air we breathe is nitrogen.
The Haber-Bosch process turns nitrogen from the air into ammonia for fertilizer, and it helps feed about half the world's population.
Liquid nitrogen boils at about −196°C (−321°F).
Scottish scientist Daniel Rutherford discovered nitrogen in 1772.
Divers get the bends when nitrogen dissolved in their blood forms bubbles because they rise to the surface too quickly.
Laughing gas is nitrous oxide, a compound of nitrogen and oxygen, and chemist Humphry Davy held parties where people inhaled it in the early 1800s.
Chip bags are filled with nitrogen to keep the chips fresh and protect them from being crushed.
Lightning breaks apart nitrogen molecules in the air, creating compounds that fall to the ground and help fertilize plants.
The bases that make up DNA contain nitrogen.
Alfred Nobel invented dynamite by stabilizing nitroglycerin, a nitrogen compound, and later used his fortune to create the Nobel Prizes.
About 21% of Earth's air is oxygen.
Oxygen is the most abundant element in Earth's crust, making up about 46% of its mass.
Oxygen is the most abundant element in the human body, making up about 65% of its mass, mostly in the form of water.
About 2.4 billion years ago, tiny cyanobacteria began releasing so much oxygen through photosynthesis that it transformed Earth's atmosphere, in what scientists call the Great Oxidation Event.
Oxygen was discovered independently by Carl Wilhelm Scheele and Joseph Priestley in the 1770s, and Antoine Lavoisier named it.
Liquid oxygen is pale blue and is attracted to magnets.
Ozone is a molecule made of three oxygen atoms, and the ozone layer protects Earth from harmful ultraviolet radiation.
Rust is iron oxide, which forms when iron reacts with oxygen and water.
Ocean phytoplankton produce about half of Earth's oxygen.
Liquid oxygen is used as an oxidizer in rocket fuel.
Gold's chemical symbol, Au, comes from the Latin word "aurum."
All the gold ever mined would fit into a cube roughly 22 meters on each side.
Much of the universe's gold is thought to be created when neutron stars collide, which scientists observed for the first time in 2017.
Gold is so malleable that a single ounce can be hammered into a sheet covering about 300 square feet.
Pure gold leaf is edible and is sometimes used to decorate fancy desserts.
Gold doesn't rust or tarnish.
Fort Knox holds about 147 million ounces of gold.
Olympic gold medals are mostly made of silver, with a gold plating.
Smartphones contain small amounts of gold in their electronics.
The largest gold nugget ever found, the Welcome Stranger, was discovered in Australia in 1869.
Earth's core is made mostly of iron.
Iron is the most common element on Earth by mass.
Blood is red because of iron in hemoglobin.
Iron's chemical symbol, Fe, comes from the Latin word "ferrum."
King Tut's dagger was made of iron from a meteorite.
Delhi's Iron Pillar has resisted rust for about 1,600 years.
Massive stars collapse once they start fusing iron.
Steel is made mostly of iron mixed with a small amount of carbon.
The Iron Age began around 1200 BC.
Mars is red because of iron oxide, or rust, on its surface.
Silver conducts electricity and heat better than any other metal.
Silver's symbol, Ag, comes from the Latin "argentum," and Argentina is named after silver.
Silver is antimicrobial.
Silver tarnishes when it reacts with sulfur compounds in the air.
Traditional film photography used light-sensitive silver halides.
Mexico produces the most silver in the world.
Silver iodide is used in cloud seeding to encourage rain or snow.
Sterling silver is 92.5% silver.
The Hunt brothers tried to corner the silver market, which led to a price crash known as Silver Thursday in 1980.
In folklore, silver bullets are said to kill werewolves.
Uranium was discovered in 1789 and named after the planet Uranus, discovered in 1781.
Henri Becquerel discovered radioactivity in 1896 using uranium salts.
About two billion years ago, uranium deposits at Oklo in Gabon formed a natural nuclear reactor.
Only about 0.7% of natural uranium is uranium-235.
Uranium glass glows green under ultraviolet light.
Uranium is the heaviest element found in large natural amounts.
Kazakhstan produces the most uranium in the world.
Uranium-238 has a half-life of about 4.5 billion years, about the age of Earth.
Some old Fiestaware used a red glaze containing uranium.
A single uranium fuel pellet can make about as much energy as a ton of coal.
Sodium reacts violently with water.
Sodium's symbol, Na, comes from the Latin "natrium."
Humphry Davy first isolated sodium in 1807 using electrolysis.
Table salt is made of sodium, a reactive metal, and chlorine, a toxic gas.
Some streetlights glow yellow because they use sodium vapor.
Sodium is stored under oil to keep it from reacting with air and moisture.
Nerve signals depend on sodium moving in and out of cells.
Sodium is soft enough to cut with a knife.
Americans eat about 3,400 milligrams of sodium a day on average, well above the recommended limit of 2,300 milligrams.
Seawater is about 3.5% salt.
Mercury is the only metal that's liquid at room temperature.
Mercury's symbol, Hg, comes from the Latin "hydrargyrum," meaning "liquid silver."
The phrase "mad as a hatter" is linked to hatmakers who were poisoned by mercury used to make felt.
China's first emperor, Qin Shi Huang, is believed to have died after taking mercury pills he thought would make him immortal.
Mercury thermometers have been phased out because mercury is toxic.
Minamata disease is mercury poisoning named after a Japanese city where industrial waste contaminated fish.
Mercury is named after the planet Mercury and the Roman god.
Mercury is so dense that iron can float on it.
Fluorescent light bulbs contain small amounts of mercury.
Large fish like tuna can contain higher levels of mercury.
The Statue of Liberty is covered in copper, which turned green as it reacted with the air.
Copper's symbol, Cu, comes from the Latin "cuprum," named after Cyprus.
Copper surfaces can kill many germs.
The Copper Age came before the Bronze Age.
Ötzi the Iceman carried a copper axe.
Chile produces the most copper in the world.
Octopus blood is blue because it uses copper-based hemocyanin.
Copper is used in wiring because it conducts electricity well.
Copper compounds give fireworks blue and green colors.
US pennies made since 1982 are mostly zinc with a thin copper coating.
A glowing protein from the crystal jelly led to the 2008 Nobel Prize in Chemistry.
Tests of Isaac Newton's hair found high levels of mercury, probably from his alchemy experiments.
Marie Curie was the first woman to win a Nobel Prize, and she's the only person to win Nobel Prizes in two different sciences, physics and chemistry.
Marie Curie discovered polonium, named after her home country of Poland, and radium.
Marie Curie's daughter Irène Joliot-Curie won a Nobel Prize in Chemistry in 1935.
Scientists found ethyl formate, the chemical that helps give raspberries their flavor, in a dust cloud near the center of the Milky Way.
Jennifer Doudna and Emmanuelle Charpentier won the 2020 Nobel Prize in Chemistry for CRISPR.