105 Fun Facts About Carbon

What is carbon's atomic number?

6. That leaves four electrons in its outer shell, which is why carbon usually forms four bonds.

In diamond, each carbon atom's four bonds point to the corners of what shape?

Tetrahedron. That rigid network of strong bonds is why diamond is the hardest natural substance.

Coal formed mostly from the buried remains of what?

Ancient swamp plants. They rotted into peat, and millions of years of heat and pressure under buried sediment turned that peat into coal.

Carbon ranks where in abundance among elements in the universe by mass?

Fourth. Only hydrogen, helium and one heavier element outrank it, yet almost none of that carbon was made in the Big Bang.

By mass, which element is more plentiful in the human body than carbon?

Oxygen. Water makes up over half the body's weight, and water is mostly oxygen by mass.

Which form of carbon traps impurities in gas masks and water filters?

Activated charcoal. It is riddled with tiny pores, and impurities stick to all of that inner surface.

Graphite gets its name from a Greek verb meaning what?

To write. Thousands of years before it had that name, prehistoric potters in the Balkans painted their pots with it.

Graphite's carbon atoms bond in flat sheets; what holds those sheets together?

Van der Waals forces. They are weak, so the sheets glide past each other, which is why graphite works as a dry lubricant.

Why is 'diamonds are forever' technically untrue?

They should slowly turn into graphite, because graphite, not diamond, is carbon's most stable form at everyday conditions.

What is a two-dimensional sheet of carbon atoms in a hexagonal lattice called?

Graphene. Andre Geim and Konstantin Novoselov pulled one-atom-thick flakes of it off graphite using ordinary adhesive tape.

Buckminsterfullerene was named after an architect famous for designing what?

Geodesic domes. The discoverers thought the molecule's cage of hexagons and pentagons looked like one of Buckminster Fuller's domes.

Which honour did Curl, Kroto and Smalley win for discovering fullerenes?

The Nobel Prize in Chemistry. The find set off a wave of research into other new forms of carbon.

How many carbon atoms make up buckminsterfullerene, the best-known buckyball?

60. Clusters of 60 atoms proved unusually stable, which led their discoverers to deduce a closed, highly symmetrical cage.

Which carbon allotrope, found in 1997, is ferromagnetic and among the lightest solids at about 2 kg per cubic metre?

Its atoms are strung together in a loose 3D web of six- and seven-membered rings.

How was Q-carbon first made?

By firing a laser pulse at amorphous soot. The flash melts the carbon, which is then quenched so fast that the Q stands for 'quenched'.

Which material is the top candidate for the cable of a space elevator?

Carbon nanotubes. A Japanese builder has floated a nanotube space elevator by 2050, but the idea remains highly speculative.

What is the half-life of carbon-14?

About 5,700 years. Living things keep topping up their carbon-14, so the decay clock only starts once they die.

How is carbon-14 created?

Cosmic rays hitting nitrogen in the upper atmosphere make it, and 1950s and 1960s nuclear bomb tests nearly doubled the amount in the air.

Which chemist developed radiocarbon dating?

Willard Libby. To prove the method worked, his team tested it on ancient Egyptian artefacts whose ages were already known.

In 1988, radiocarbon labs in Arizona, Oxford and Zurich all tested samples from what?

The Shroud of Turin. Their tests dated its linen to between 1260 and 1390, centuries after the time of Jesus.

Which isotope did IUPAC adopt as the basis for atomic weights?

Carbon-12. Every relative atomic mass on a periodic table is still measured against it.

Carbon nuclei are forged in stars by which fusion route?

The triple-alpha process. Three helium nuclei must fuse almost at once, because the two-nucleus stepping stone, beryllium-8, falls apart instantly.

Why was no significant carbon created in the Big Bang?

It expanded and cooled too fast, so almost all the carbon around today was forged later, inside stars.

What is coal baked into, without air, to fuel iron-smelting blast furnaces?

Coke. It is strong enough not to be crushed by the ore piled above it, so hot gases can still rise through the furnace.

What colour does diatomic carbon, the gas that lights up many comets, glow when excited?

Green. The gas can't last at room temperature, quickly linking up into bigger carbon molecules.

Which element sits directly below carbon in the periodic table?

Silicon. It is a semiconductor, which is why most computer chips are built on it.

Carbon's ability to form long chains of carbon-carbon bonds is called what?

Catenation. It lets carbon build the long backbones of fuels, plastics and the molecules of life.

Which chemist showed in 1772 that diamond is carbon by burning it?

Antoine Lavoisier. His science was funded by a hated tax-collecting firm, and that job got him guillotined in the French Revolution.

Before Scheele's work, graphite had been widely thought to be a form of which metal?

Lead. That old confusion is why pencil cores are still called 'lead', though they hold none of the metal.

Which scientist, better known for his temperature scale, showed that iron becomes steel by absorbing a substance?

Réaumur. He also showed that some animals really can regrow limbs they have lost.

Which English valley's graphite was so pure and solid it could be sawn straight into sticks?

Borrowdale, Cumberland. Its graphite lined moulds for cannonballs, so the Crown took over the mine and guarded it.

Which odourless gas makes up most of natural gas?

Methane. Gas companies add mercaptan, which smells like rotten eggs, so that leaks can be noticed.

Natural diamonds are found in which volcanic rock?

Kimberlite. Digging into it during the diamond rush at Kimberley, South Africa, carved out the vast pit called the Big Hole.

Which country was the world's main source of diamonds for centuries, until the 1700s?

India. As its supplies ran low, newly discovered Brazilian diamonds took over the market.

Which mine, the world's main source of pink diamonds, closed in 2020 after 37 years?

The Argyle mine. At times it produced more diamonds by volume than any other mine, though few of them were gem quality.

Which American company announced in 1955 that its lab had made diamonds?

General Electric. Its scientists squeezed graphite under enormous pressure and heat, with a metal catalyst to help.

Before X-ray fluorescence, how were diamonds separated from crushed ore?

The final sorting steps are still done by hand.

Which US state has a park where visitors can dig for diamonds and keep what they find?

Arkansas. The search field is the eroded surface of an ancient volcanic crater that carried diamonds up from deep underground.

Carbon fibre is made by pyrolysing filaments of which polymer?

Polyacrylonitrile (PAN). Its filaments are stretched to line up the molecules before baking, which makes the finished fibre strong for its size.

What were the 61 tattoos on Otzi the Iceman made from?

Fireplace soot. Carbon stays put once it's in the skin, which is why the tattoos lasted some 5,200 years after his death.

Graphite serves what role in some nuclear reactors?

Neutron moderator. It slows neutrons, but energy stored in it can escape suddenly, and a botched attempt to release it set off Britain's Windscale fire.

Which grade of coal has the highest carbon content?

Anthracite. Extra heat underground drove off most of its volatile matter, leaving it at least 86% carbon.

Carbon combines with tungsten to form a carbide widely used for what?

Abrasives and hard cutting-tool tips. Carbide-tipped tools can cut metal far faster than tools made of high-speed steel.

Photosynthetic plants pull carbon dioxide from the air and build it into biomass in which named pathway?

The Calvin cycle. Melvin Calvin's Berkeley team mapped it by following radioactive carbon-14 through photosynthesis.

Which carbon allotrope has a hexagonal crystal lattice and properties similar to diamond?

It forms under some conditions where cubic diamond would normally appear.

Chalk, marble and which other common rock are mostly calcium carbonate?

Limestone. Much of it built up from the shells and corals of sea creatures, making it one of Earth's biggest stores of carbon.

Which isotope of carbon is used in NMR to study organic molecules?

Mass number 13. Its nuclear spin of one half lets NMR detect it, even though it is only about 1% of natural carbon.

Radiocarbon dating works on remains up to roughly what age?

About 50,000 years. Beyond that too little carbon-14 is left to measure, though special methods occasionally push further.

More than 20% of the carbon in the universe may be locked up in which class of compounds?

Polycyclic aromatic hydrocarbons. The 'PAH world' hypothesis suggests these ring molecules helped produce life's first building blocks.

How much carbon is estimated to be dissolved in all of Earth's water bodies?

About 36,000 gigatonnes, roughly 40 times what the atmosphere holds, and the open ocean keeps absorbing CO2 from the air.

Where in space have astronomers detected buckyball molecules?

In planetary nebulae. Ionised buckyballs also drift in the space between stars, where they absorb some of the starlight.

Where in the Solar System are carbon-rich asteroids relatively most common?

The outer asteroid belt. In 2020 Japan's Hayabusa2 brought home samples of Ryugu, a carbon-rich asteroid, holding organic compounds.

Which early electric light lit city streets from the late 1870s, before incandescent bulbs took over?

The arc lamp. Its light came from an electric arc between two carbon rods, which slowly burned away and needed adjusting.

Radioactive carbon-11 is used to label tracers for which kind of medical scan?

PET scans. Carbon-11 has a half-life of only about 20 minutes, so chemists must attach it to tracer molecules very quickly.

What is the German word for carbon?

Kohlenstoff. The name means 'coal substance', yet even the richest coal isn't pure carbon, while diamond and graphite are.

Carbon black, a fine powder made by burning oil with little air, mainly goes into which everyday product?

Car tires take about 70% of all carbon black. The powder reinforces the rubber and protects it from wear, which is why tires are black.

Carbon paper, once used to duplicate typed letters, left which abbreviation behind in every email program?

The cc line stands for carbon copy: typists made duplicates by sandwiching inked carbon paper between sheets, and the label outlived the paper.

Thomas Edison's team found that a carbonized filament from which plant let a light bulb glow for over 1,200 hours?

Bamboo from Japan, charred into a thin carbon thread, beat the cotton, linen and paper Edison's patent had listed and lit some of the first commercial bulbs.

August Kekulé said a daydream of a snake seizing its own tail showed him the ring shape of which molecule?

Benzene had puzzled chemists until Kekulé proposed in 1865 that its carbon atoms join in a closed ring. He told the snake story at a celebration 25 years later.

Pouring concentrated sulfuric acid onto which kitchen ingredient makes a black column of carbon rise like a snake?

Table sugar is stripped of its water by the acid, leaving a lump of black carbon that the escaping hot gases puff up into a snake-like column.

Andre Geim and Konstantin Novoselov first isolated one-atom-thick sheets of carbon in 2004 using which household item?

Sticky tape pulled ever-thinner flakes off a lump of graphite until a single layer was left. The method is still known as the Scotch tape technique.

A white dwarf star with a crystallized carbon core was nicknamed Lucy after a song by which band?

The Beatles recorded Lucy in the Sky with Diamonds, and the star BPM 37093 took the name because its core may be one of the largest diamonds in our part of the universe.

Diamond defines the top of which mineral hardness scale, introduced by a German geologist in 1812?

Mohs ranked minerals by which one can scratch which. The steps are uneven: diamond at 10 is about four times as hard as corundum at 9.

Nicolas-Jacques Conté's 1795 recipe for pencil cores mixes powdered graphite with which material, fired in a kiln?

Clay makes the core harder and its mark lighter the more of it is added. Conté devised the mix when a blockade cut France off from British graphite.

Which explosive, one of the Four Great Inventions of China, mixes sulfur and saltpeter with carbon from charred wood?

Gunpowder burns its carbon and sulfur as fuel while the saltpeter acts as the oxidizer. The classic recipe by weight is 75% saltpeter, 15% carbon fuel and 10% sulfur.

Graphite forms the negative electrode in which rechargeable battery type that powers most phones and electric cars?

Lithium-ion cells slot their lithium ions into the graphite as they charge and draw them back out as they discharge, a process called intercalation.

Which 1997 climate treaty set legally binding targets for industrialized countries to cut carbon dioxide emissions?

The Kyoto Protocol bound 37 industrialized countries and the European Community to emission targets. The 1992 climate convention it built on had set no binding limits.

Which branch of chemistry is devoted to carbon-containing compounds, from plastics and perfumes to medicines?

Organic chemistry dates from a time when chemists believed compounds from living organisms held a vital force that set them apart from mineral ones.

Gem testers tell diamond from imitations by how well it conducts what, better than any other natural material?

Heat flows through diamond so readily that electronic thermal probes are widely used to separate real stones from look-alikes, even though diamond barely carries electricity.

Most natural diamonds formed 150 to 250 kilometers underground, in which layer of the Earth?

The mantle squeezed and heated carbon into diamond between 1 and 3.5 billion years ago, and rare, fast eruptions later carried the crystals up to the surface.

Coal, petroleum and natural gas, the main sources of human carbon dioxide emissions, share which collective name?

Fossil fuels take millions of years to form, which is why they count as non-renewable. In 2023 they supplied 77% of the world's primary energy.

Like sulfur and phosphorus, carbon belongs to which broad class of elements that tend to gain or share electrons?

Nonmetals number only about seventeen, yet a handful of them, carbon included, make up the bulk of Earth's atmosphere, oceans, biosphere and crust.

Frozen carbon dioxide, used in theaters to make low-lying stage fog, is sold under which everyday name?

Dry ice got its common name from a 1925 trademark. At about −78 °C it is cold enough to cause frostbite, and dropped in water it makes dense, ground-hugging fog.

Plastics, proteins and DNA are all giant carbon-based molecules built from repeating units, known by which name?

Polymers form when many small molecules called monomers link into one long chain. In most plastics the backbone of that chain is mainly carbon atoms.

Loose granules of carbon turned voices into electrical signals inside which everyday device from 1890 until the 1980s?

The telephone relied on the carbon microphone for nearly a century: sound squeezed the granules together, lowering their resistance and shaping the current on the line.

Carbon heads which numbered group of the periodic table, the column that also holds germanium and tin?

Group 14 is also called the carbon group. Its members run from carbon at the top down to flerovium, a synthetic element that lasts only seconds.

Which oil company's mid-2000s advertising campaign popularized the idea of a personal carbon footprint?

BP hired the advertising agency Ogilvy to promote the footprint for individuals. Critics argue the aim was to shift responsibility from corporations onto personal lifestyle choices.

Which astronomer described carbon chauvinism, the assumption that alien life must be built on carbon as ours is?

Carl Sagan used the term as early as 1973 for one of several human chauvinisms that he said limit our imagination of possible extraterrestrial life.

What caused the amount of carbon-14 in Earth's air to almost double during the 1950s and early 1960s?

Nuclear tests above ground by the US, Soviet Union and Britain ended with a 1963 treaty. The extra carbon-14 they left now helps forensic scientists date human tissue and even vintages of wine.

Friedrich Wöhler showed in 1828 that which compound of living bodies could be made from non-living starting materials?

Urea, found in urine, had been known only as a product of living bodies. Wöhler got it by treating silver cyanate with ammonium chloride.

The carbon–fluorine bond, one of the strongest single bonds in chemistry, makes which household material almost inert?

Teflon is so unreactive that it lines containers and pipework for corrosive chemicals, and almost nothing sticks to it, which is why it coats frying pans.

Miners' and cavers' carbide lamps burn which gas, made by dripping water onto calcium carbide?

Acetylene burns with a bright open flame, and miners soon put the lamp's warmth to use as well. Cavers nicknamed the trick of trapping its warmth under a poncho the Palmer furnace.

Carbon anodes are slowly burned away in the Hall–Héroult process, which makes which lightweight metal from molten ore?

Aluminum collects as a liquid at the cathode while the anodes are eaten away into carbon dioxide, so smelters have to keep replacing them.

Terra preta, a fertile black soil that ancient farmers made by adding charred wood, is found in which river basin?

The Amazon basin's natural soil is poor, but the added char stays stable for thousands of years, binding and holding on to minerals and nutrients.

The carat, the unit used to weigh diamonds, takes its name from the seeds of which Mediterranean tree?

Carob seeds were long used to weigh jewelry because people believed they barely varied in mass. Today the carat is fixed at exactly 200 milligrams.

In diamond, every carbon atom is locked to its neighbors in a three-dimensional network by which type of chemical bond?

Covalent bonds, in which atoms share electrons, link a diamond into one giant structure. The same kind of bond joins the atoms within each flat sheet of graphite.

Which black gemstone, made fashionable by Queen Victoria's mourning jewelry, is actually a form of coal?

Jet is a low-rank coal formed from wood that decayed millions of years ago. It polishes so darkly that it gave English the adjective jet-black.

Heated carbon skips the liquid stage at normal pressure, turning straight from solid to gas in which process?

Sublimation sets in at about 3,900 K, the highest sublimation point of any element. Carbon melts only under more than 100 times normal air pressure.

Scientists first corrected radiocarbon dates in the 1960s by checking them against which natural yearly record?

Tree rings work because a tree adds carbon only to its outermost ring each year. Overlapping series from old timber gave a continuous record spanning 8,000 years.

Ethanol and dimethyl ether contain exactly the same atoms joined in a different order, making them examples of what?

Isomers can be entirely different substances: one of this pair is an alcohol and the other an ether. Berzelius introduced the term isomerism in 1830.

NASA's OSIRIS-REx spacecraft returned samples to Earth in 2023 from which dark, carbon-rich near-Earth asteroid?

Bennu was chosen because its pristine carbon-rich material dates from before Earth formed and holds a key ingredient of the molecules life needs.

Which Formula One team's 1981 car pioneered a monocoque chassis made wholly from carbon-fiber composite?

McLaren designer John Barnard planned the car after watching Rolls-Royce engineers build a turbofan engine with the material, an approach now universal in the sport.

Which Swedish chemist calculated in 1896 how much extra carbon dioxide in the air would warm Earth's surface?

Svante Arrhenius was trying to explain the ice ages when he made the estimate. He later wrote that industry's burning of coal could raise the level of the gas perceptibly.

Which British astronomer predicted the energy state of the carbon nucleus that lets stars make carbon at all?

Fred Hoyle worked out that the key reaction would be a billion times more productive if the state existed, predicted its energy, and was later proved right by experiment.

Carbon acts as a catalyst in which fusion sequence that dominates in stars more than 1.3 times the Sun's mass?

The CNO cycle fuses four protons into helium. Its carbon is used up at one step and regenerated at a later one, so none is consumed overall.

Animals, plants and microbes all release carbon dioxide through which sugar-burning process in their cells?

Respiration is technically a slow, controlled form of combustion: cells release the energy in sugar step by step, giving off carbon dioxide as a leftover.

Charles David Keeling began tracking rising carbon dioxide in 1958 from which Hawaiian volcano?

Mauna Loa was chosen because it is remote, far from any continent and bare of vegetation. Its record, the Keeling Curve, has run ever since.

Fungi and bacteria that recycle the carbon in fallen leaves and dead animals play which role in an ecosystem?

Decomposers, on a broad definition, are not only microbes: earthworms and woodlice digest dead matter inside their bodies, though stricter definitions call those animals detritivores.

Which thawing Arctic feature holds more than twice as much carbon as the whole atmosphere?

Permafrost is packed with dead plants and animals that piled up over millennia without fully rotting. Once it thaws, microbes get to work and greenhouse gases escape.

Which microscopic drifting sea organisms carry out about half of all the photosynthesis on Earth?

Phytoplankton manage that feat while amounting to only about 1% of the world's plant biomass.

Jan Baptist van Helmont grew a willow for five years and concluded its added weight came entirely from what?

Water was all he had added, and the soil had lost just 57 grams. He missed the carbon dioxide the tree drew from the air, although he himself coined the word gas.

A reservoir that absorbs more carbon than it releases, as a growing forest does, is called a carbon what?

Sink capacity can be lost: deforestation and industrial farming have depleted natural ones on land. Globally, the two most important are vegetation and the ocean.

Which landscapes cover only about 3% of the world's land yet store more carbon than all of its forests?

Peatlands stay so wet that dead plants never fully rot, so layer upon layer of carbon builds up. Their peat holds about 42% of all the carbon in the world's soils.

Which name did explorer William Beebe give the shower of debris that carries carbon down to the deep sea?

Marine snow can drift for weeks before it reaches the seabed, where it feeds deep-sea life and keeps its carbon out of contact with the air for a very long time.

Rain turned mildly acidic by carbon dioxide slowly dissolves rock in which geological process?

Weathering speeds up when the climate warms and rainfall rises, so it pulls more carbon out of the air, a slow natural brake that works over millions of years.