178 Fun Facts About Chemistry

Which chemist created the first widely accepted periodic table?

Dmitri Mendeleev left gaps in his table for elements nobody had found and forecast their properties; three of them were discovered within twenty years, closely matching his predictions.

Beyond solid, liquid and gas, what is usually counted as the fourth state of matter, the stuff of stars and lightning?

Plasma forms when a gas is heated or electrified until electrons break free of its atoms, which is why it conducts electricity and glows, as in a neon sign.

What type of chemical reaction absorbs heat energy from its surroundings?

Endothermic changes soak up heat from their surroundings, which is how an instant cold pack works: squeezing it lets ammonium nitrate dissolve in water, and the pack turns cold.

Dry ice is the frozen form of which gas?

Carbon dioxide has no liquid state at normal pressure, so dry ice at −78.5 °C turns straight into gas, keeping food frozen without leaving a puddle.

What subatomic particle found in the nucleus of an atom carries a positive electric charge?

Proton: the number of protons fixes which element an atom is, so no chemical reaction could turn lead into gold as the alchemists hoped; that takes a nuclear change.

What is the chemical symbol for the element gold?

Au is short for aurum, gold's Latin name. Gold is so unreactive that it is usually found in nature as the pure metal, in nuggets and grains, and not locked up in a compound.

What is the common name for sodium chloride?

Table salt joins two hazards: sodium, a soft metal that reacts violently with water, and chlorine, a poisonous gas. Bonded together, they are safe to sprinkle on dinner.

Which acid does the human stomach produce to help digest food?

Hydrochloric acid would damage the stomach itself, so the lining shields itself with mucus and bicarbonate; heartburn is what happens when the acid escapes up into the gullet.

What is the approximate pH of pure water at 25°C?

Pure water at 25 °C has a pH of 7: H⁺ and OH⁻ are both 10⁻⁷ mol/L, so it is neutral. Heated above 25 °C, the neutral point drifts below 7.

What type of chemical bond has atoms sharing electron pairs, the kind that holds a water molecule together?

A Covalent bond shares electrons; an ionic bond transfers them, a metallic bond pools them, and a hydrogen bond is just an attraction between molecules, the one that makes ice float.

Which functional group has a carbon double-bonded to oxygen and bonded to a hydrogen and an R group?

Aldehyde: when the body breaks down the ethanol in drinks, the first product is acetaldehyde, a toxic member of this family that contributes to hangovers.

In a redox reaction, what term describes the loss of electrons by a chemical species?

Oxidation once meant only combining with oxygen; chemists later widened it to any loss of electrons, remembered as OIL RIG: oxidation is loss, reduction is gain.

Which reaction type has an acid and a base forming a salt and water?

Neutralization is how milk of magnesia settles heartburn: its magnesium hydroxide, a base, reacts with excess stomach acid to leave a salt and water.

What is the typical oxidation number of an uncombined element?

0 is the oxidation number of any free element: in oxygen gas or a lump of iron every atom is bonded only to its own kind, so none has gained or lost electrons.

Which transition metal forms the outer skin of the Statue of Liberty?

Copper, like most transition metals, forms strongly coloured compounds: the statue was as brown as a penny when new, and its skin weathered to a green patina that protects the metal beneath.

Which functional group contains a carbonyl group bonded to two other carbon atoms?

Ketone: the simplest is acetone, the solvent in nail-polish remover, and the body makes ketones of its own when it burns fat for fuel, the 'keto' in a ketogenic diet.

An organic compound whose molecule carries a –COOH group belongs to which class?

A carboxylic acid is what makes vinegar and lemons sour: acetic acid and citric acid both carry the –COOH group, which gives up its hydrogen as an ion in water.

Which functional group, with the structure R-COO-R', gives many fruits their sweet smells?

Ester molecules give bananas, pineapples and pears their scent: isoamyl acetate is sold as 'banana oil', and the flavour industry uses esters to imitate fruit.

What name is given to a metal blended with other elements, as bronze and steel are?

Alloy: blending changes how a metal behaves, so bronze is harder than either of the metals melted into it, and a little carbon turns iron into much stronger steel.

Which gas makes up about 78% of Earth's atmosphere by volume?

Nitrogen fills most of the air, yet plants and animals cannot use it as a gas: its triple bond is so strong that life depends on certain bacteria, and lightning, to 'fix' it.

A solution with a pH of 2 is considered what type of substance?

Acidic, and strongly so: the pH scale is logarithmic, so each step down means ten times more acidity, making pH 2 a thousand times more acidic than pH 5.

Who is credited with the discovery of the electron?

J.J. Thomson showed in 1897 that cathode rays are particles far smaller than atoms; forty years on, his son George shared a Nobel Prize for proving that electrons also behave as waves.

What is the primary chemical compound found in rust?

Iron oxide in the form of rust is flaky and falls away, exposing fresh metal to corrode, whereas many other metals grow a tight oxide film that seals the surface.

Which group of elements, with full outer electron shells, sits in the periodic table's last column and barely reacts with anything?

Noble Gases had no place in the first periodic tables because none had yet been isolated; once the first was isolated in the 1890s, a whole new column was added to hold the family.

Which gas gives rotten eggs their smell?

Hydrogen sulfide is smelled at the faintest trace, yet at high concentrations it deadens the sense of smell within minutes, so the warning vanishes just as the gas becomes dangerous.

What is the name for a solid changing directly into a gas without first becoming a liquid?

Sublimation is why snow can shrink on dry, sub-zero days without ever melting, and it is the trick behind freeze-dried food: the ice is drawn off as vapour under low pressure.

Atoms of the same element with different numbers of neutrons, such as carbon-12 and carbon-14, are called what?

Isotopes of an element share one square of the periodic table, and that is what the name says: it was coined in 1913 from the Greek for 'same place'.

What term describes a substance that speeds up a chemical reaction without being consumed?

A catalyst works by opening an easier route for the reaction; the platinum in a car's catalytic converter turns toxic exhaust gases into less harmful ones without being used up.

What type of chemical reaction releases energy, often as heat or light?

Exothermic reactions give out more energy than it takes to start them: burning is the classic case, and the iron powder in a disposable hand warmer heats up as it reacts with air.

What type of hybridization does the carbon atom exhibit in a methane (CH₄) molecule?

sp³ means one s and three p orbitals blend into four identical ones pointing to the corners of a tetrahedron, so methane is not the flat cross it looks on paper: its bonds sit about 109.5° apart.

By the classic definition, an acid dissolved in water raises the concentration of which ion?

Hydronium (H₃O⁺) forms because a bare hydrogen ion cannot exist on its own in water: it latches onto a water molecule at once, and pH is a measure of how many there are.

Which allotrope of carbon is the hardest natural material known?

Diamond and soft, slippery graphite are both pure carbon: in diamond every atom is locked to four neighbours in a rigid 3D framework, while graphite's flat sheets glide over one another.

What kind of solution holds its pH steady when small amounts of acid or base are added, as blood does?

A Buffer solution pairs a weak acid with its conjugate base, so either can mop up added H⁺ or OH⁻; blood's bicarbonate buffer holds it near pH 7.4.

What is the minimum energy reactants must have before a chemical reaction can occur?

Activation energy is why a match needs striking: wood and oxygen want to react, but they need a push over the barrier to the transition state first.

What are molecules with the same formula and bonding sequence but different 3D orientation of atoms called?

Stereoisomers can behave very differently: one mirror-image form of carvone smells of spearmint and the other of caraway, because the nose's receptors tell the two apart.

Doctors treat lead poisoning with drugs that grip metal ions like a claw, a process known as what?

Chelation takes its name from the Greek for 'claw': a drug such as EDTA wraps around a lead ion at several points, and the bound metal is then flushed out of the body.

Which rule of chemistry says a system at equilibrium shifts to counteract any change imposed on it?

Le Chatelier's Principle explains why ammonia plants run at high pressure: four volumes of gas become two, so squeezing the mixture pushes the equilibrium towards ammonia.

Which set of four numbers pins down the state of each electron in an atom?

Quantum numbers come four to an electron, and no two electrons in an atom can share all four; that rule forces electrons into separate shells and so shapes the periodic table.

Which family of organic compounds is defined by a hydroxyl group (-OH) attached to a saturated carbon atom?

Alcohol in chemistry is a whole family, and the drinkable one, ethanol, is just the two-carbon member; the word comes from the Arabic al-kuhl, the original kohl eyeliner.

Which constant, exactly 6.02214076 × 10²³ per mole, links an amount of substance to its number of particles?

Avogadro's number has been an exact figure since 2019, so a mole is now defined by counting particles rather than by the mass of carbon-12. Avogadro himself never calculated it.

Apart from mercury, which is the only element that is a liquid at standard temperature and pressure?

Bromine is a dense red-brown liquid whose fumes are so foul that its name means 'stench'; it is the only non-metal that is liquid at room temperature.

What is the chemical symbol for potassium?

K stands for kalium, a Latinised name from the Arabic for plant ashes, the root that also gave English 'alkali'; potassium itself is named after potash.

Which type of radioactive decay involves the emission of a helium nucleus?

Alpha decay is where most of Earth's helium comes from: each particle thrown out by uranium or thorium in the rocks becomes a helium atom, later tapped along with natural gas.

What technique separates a mixture's components between a stationary phase and a mobile phase?

Chromatography separates a mixture by carrying it in a mobile phase over a stationary phase; Mikhail Tsvet coined the name in 1906 after separating plant pigments into coloured bands on a chalk column.

Which process splits water into hydrogen and oxygen by passing a current through it?

Electrolysis forces reactions that would never run on their own: the same method splits salt water into chlorine and caustic soda, and plates one metal with a thin coat of another.

Which industrial process makes ammonia by combining nitrogen from the air with hydrogen at high pressure?

Haber-Bosch replaced mined nitrates and guano as farming's main supply of nitrogen; by one widely cited estimate, fertiliser made with its ammonia feeds about half the world's people.

Which class of large molecules is built from repeating units, found in plastics and natural materials like DNA?

Polymers were long doubted: when Hermann Staudinger argued in the early 1920s that rubber consists of giant chain molecules, he was defying the prevailing theory; it won him the 1953 Nobel Prize.

What term refers to measuring the heat changes of chemical reactions or physical changes?

Calorimetry is how the energy in food was first measured: a dried sample is burned in a sealed 'bomb' and the heat is read from the temperature rise of the water around it.

Which group-18 element has the highest atomic number?

Oganesson, element 118, was named in 2016 for the physicist Yuri Oganessian; its atoms last less than a millisecond, so nearly everything said about its chemistry is prediction.

On the Pauling scale, which element has the highest electronegativity, at 3.98?

Fluorine tops the Pauling scale at 3.98, and that hunger for electrons makes it so reactive that isolating it took chemists decades and poisoned many of those who tried.

Which organomagnesium reagents, named for a 1912 Nobel laureate, are used to form carbon-carbon bonds?

Victor Grignard shared the 1912 Nobel Prize in Chemistry for the discovery; the compounds are so reactive with water that they must be prepared in dry ether.

What type of bond links amino acids together to form proteins?

A peptide bond forms when two amino acids join and give off a molecule of water; digestion runs the step in reverse, using water to cut proteins back into amino acids.

Which term describes elements with atomic numbers greater than 92?

Transuranic elements have atomic numbers above 92, uranium's; all are radioactive and, apart from traces of neptunium and plutonium, are made artificially. Neptunium (93), produced in 1940, was the first.

Which superacid, able to protonate hydrocarbons, is often called the strongest known acid?

Fluoroantimonic acid, a mix of hydrogen fluoride and antimony pentafluoride, is so aggressive that it attacks glass and has to be kept in containers lined with PTFE.

Which German chemist's 1828 synthesis of urea from an inorganic salt is cited as the birth of modern organic chemistry?

Friedrich Wöhler was not even trying to make urea: he set out to prepare ammonium cyanate, and the salt rearranged into a substance until then known only from living things.

August Kekulé said he hit on the ring structure of benzene after a daydream about what?

A snake seizing its own tail was not his first such vision, Kekulé said: he credited an earlier daydream, of atoms dancing as he rode a London omnibus, with his theory of how carbon atoms link into chains.

What is the general formula for the alkanes, the saturated hydrocarbons that begin with methane?

CnH2n+2 follows from the structure: every carbon in the chain carries two hydrogens, plus one extra at each end, giving methane CH₄, ethane C₂H₆ and propane C₃H₈.

Which is the smallest alkane that can form a branched chain?

Butane's four carbons can form a straight chain or a branched one, isobutane; pentane has three isomers, decane 75, and the count keeps exploding as chains grow.

Which pair of German chemists shared the 1950 Nobel Prize for the cycloaddition that builds a cyclohexene ring in one step?

Diels and Alder first described their reaction in 1928; it forms two carbon-carbon bonds at once with predictable stereochemistry, which is why synthetic chemists love it.

Which 18-year-old accidentally made the synthetic dye mauveine in 1856 while trying to make quinine?

William Henry Perkin was oxidising aniline with potassium dichromate when a purple residue appeared; he patented it as a dye, and its success launched the synthetic dye industry.

Which Russian chemist's rule predicts which carbon of an alkene's double bond takes the hydrogen when HBr adds?

Markovnikov's rule sends the hydrogen to the carbon that already holds more hydrogens; add a peroxide and the result flips, a twist Morris Kharasch called the peroxide effect.

Which scientist discovered molecular chirality in the 1840s by hand-sorting left- and right-handed tartrate crystals?

Louis Pasteur found that solutions of the two crystal forms rotated polarised light in opposite directions and correctly inferred that an asymmetric arrangement of the molecules themselves was responsible.

Which type of hydrocarbon contains at least one carbon-carbon triple bond, acetylene being the simplest?

Alkyne chemistry powers the welder's torch: acetylene, properly called ethyne, burns in pure oxygen with a flame above 3,000 °C, hot enough to cut steel.

Which German chemist with a famed Giessen teaching lab is counted among the founders of organic chemistry?

Justus von Liebig also worked out how to make concentrated beef extract; the company founded to sell it, Liebig's Extract of Meat, went on to launch the Oxo cube.

Marie Curie won her 1911 Nobel Prize in Chemistry for discovering which two elements?

Radium and polonium were both found in 1898; Curie named polonium after Poland, her homeland, which was then partitioned between three neighbouring powers.

Which chemist, who gave oxygen its name, was guillotined during the French Revolution?

Antoine Lavoisier, a tax farmer under the old regime, was charged with tax fraud and adulterating tobacco and guillotined in Paris on 8 May 1794.

Which chemist's 1661 book The Sceptical Chymist attacked the ancient idea of four elements?

Robert Boyle wrote it as a garden dialogue, arguing that matter is built from tiny corpuscles rather than Aristotle's four elements; for that he is often called the first modern chemist.

Joseph Priestley isolated oxygen in 1774 by heating which compound?

Mercuric oxide gave off a new gas when Joseph Priestley focused sunlight on it with a lens; a candle burned brighter in it, and he judged it several times better than ordinary air for breathing.

Which chemist first isolated potassium and sodium in 1807 using electricity?

Humphry Davy passed current from a large battery through caustic potash and saw globules of a new metal appear, then did the same with caustic soda; calcium and magnesium followed within a year.

Which chemist discovered benzene in 1825 and popularised the terms 'anode' and 'cathode'?

Michael Faraday isolated benzene in 1825 from the oily residue of gas made for lighting; when his work on electric currents in liquids needed new words, the scholar William Whewell supplied anode, cathode and ion.

Which Swedish chemist invented the system of letter symbols for the chemical elements?

Jöns Jacob Berzelius took one or two letters from each element's Latin name, giving symbols such as Ca and Cl; he wrote the atom counts as superscripts, where chemists now use subscripts.

Who in 1903 became the first Swedish Nobel laureate, winning the chemistry prize?

Svante Arrhenius won for showing that salts split into charged ions in water, an idea his Uppsala examiners had graded only fourth class when he presented it as his doctoral thesis.

Fritz Haber, who won the 1918 Nobel Prize for ammonia synthesis, is also called the father of what?

Fritz Haber is called the father of chemical warfare for personally directing the first chlorine attack at Ypres in April 1915; the ammonia process he won the Nobel for also underpins the fertiliser that feeds much of the world.

How many patents did Alfred Nobel hold during his life?

Alfred Nobel held 355 patents; the best known, dynamite in 1867, built the fortune that his will turned into the Nobel Prizes.

Which American chemist saw element 106 named after him?

Glenn Seaborg was still alive when seaborgium was proposed, so chemistry's naming body at first refused, ruling that no living person could be honoured that way, before accepting the name in 1997.

Which X-ray crystallographer has been called the 'dark lady of DNA'?

Rosalind Franklin died in 1958 at 37, four years before the Nobel for DNA went to Watson, Crick and Wilkins; her work on coal and viruses was the part recognised in her lifetime.

Frederick Sanger won his first Nobel Prize in 1958 for sequencing which protein?

Insulin was broken into fragments with acid and Frederick Sanger pieced their overlapping sequences together, proving for the first time that a protein has one exact order of amino acids.

Bunsen and Kirchhoff named which two elements for their blue and deep-red spectral lines?

Caesium and rubidium showed up as unfamiliar lines in Bunsen and Kirchhoff's new spectroscope; a spa's mineral water gave only about 7 grams of caesium salt, and rubidium turned up in the mineral lepidolite.

Whose X-ray work justified the concept of atomic number before he died at Gallipoli in 1915?

Henry Moseley showed that atomic number, not atomic weight, fixes an element's place in the periodic table, which exposed four gaps where elements were still undiscovered; he was 27 when he was killed.

Neon was discovered in 1898 alongside which two other gases?

Ramsay and Travers found krypton and xenon in the same 1898 campaign, fractionating liquefied air; neon's bright red emission spectrum identified it at once. Argon (1894) and helium (1895) came earlier.

The Hall–Héroult process of 1886 made which metal widely available?

Charles Martin Hall and Paul Héroult independently developed the electrolysis of alumina dissolved in molten cryolite in 1886, turning aluminium from a precious metal into a cheap one.

Which element makes up about 28% of Earth's crust by mass, second only to oxygen?

Silicon is almost never found on its own in nature despite its abundance: it is locked up with oxygen in the silicate minerals and quartz sand that make up over 90% of the crust.

Hennig Brand discovered phosphorus in 1669 while experimenting with what?

Hennig Brand, hunting for the philosopher's stone, boiled down vast quantities of urine and got a waxy solid that glowed in the dark; the name phosphorus means 'light-bearer' in Greek.

Chlorine's name comes from an ancient word meaning what?

Pale green, or yellowish green, is the meaning of the Greek chloros; the gas got the name in 1810, once it was shown to be an element and not the oxygen compound chemists had assumed since 1774.

Which gas found in air takes its name from the Greek for 'lazy' or 'idle'?

Argon comes from the Greek argos, 'idle', because Rayleigh and Ramsay, who isolated it in 1894, could not make it react with anything; krypton means 'hidden', neon 'new' and xenon 'stranger'.

Which metal has the highest electrical conductivity of any element?

Silver has the highest electrical conductivity of any element, a little ahead of copper, but its price keeps it out of household wiring and in small parts such as electrical contacts.

Which soft metal gives a creaking 'cry' when a bar of it is bent by hand?

Tin owes the sound to its crystals: bending a bar disturbs them, and the creak that results is known as the tin cry.

Iodine takes its name from the Greek word for which colour?

Violet fumes rose when Bernard Courtois added sulfuric acid to seaweed ash in 1811, and the new element was named from the Greek iodes, 'violet-coloured', for that vapour.

Which element has the highest melting point of any metal?

Tungsten has the highest melting point of any metal, around 3,400 °C, which is why it was drawn into the filaments of incandescent light bulbs; its symbol W comes from its other name, wolfram.

The word platinum comes from Spanish 'platina', meaning what?

Little silver was a slight: Spanish gold-panners in South America saw platina, a diminutive of plata, as a nuisance that spoiled their gold, and often threw it back into the river.

Which newly discovered planet did Martin Klaproth honour when naming a metal in 1789?

Uranus had been found only eight years earlier when Martin Klaproth named uranium after it; his own attempt to produce the metal failed, and pure uranium was not isolated until 1841.

Polonium was the first element discovered through which property?

Radioactivity gave polonium away in 1898: the uranium ore pitchblende was far more active than its uranium could explain, and the search for the cause turned up a new element.

Which element, found by Marguerite Perey in 1939, was the last discovered in nature, not by synthesis?

Francium showed itself when Marguerite Perey, who had begun as Marie Curie's lab assistant, purified actinium and still found radiation she could not account for; she named the element after France.

Which element, produced in 1937, was the first predominantly artificial element?

Technetium turned up in a scrap of molybdenum from Ernest Lawrence's cyclotron in California, sent to Emilio Segrè in Sicily; its name comes from the Greek technetos, 'artificial'.

Which metal, discovered by Lecoq de Boisbaudran in 1875, melts in the palm of your hand?

Gallium melts at about 30 °C, below body temperature; its discoverer said he named it for Gaul, the old name for France, though many suspect a pun on Lecoq, since a cockerel is 'gallus' in Latin.

Which element, predicted years earlier under the name eka-silicon, was discovered in 1886?

Germanium was isolated by Clemens Winkler in Freiberg from the newly found mineral argyrodite and named for his homeland; its properties matched the prediction for eka-silicon almost exactly.

Titanium was discovered in 1791 in which English county?

The clergyman William Gregor found the new metal in black sand from the Manaccan valley in Cornwall in 1791; Martin Klaproth independently discovered it in 1795 and named it after the Titans.

Which metal, famed for rainbow crystals, do magnets repel most strongly?

Bismuth pushes back against a magnetic field so strongly that a small piece of it can be made to float above strong magnets; the rainbow colours come from a thin oxide film on the crystals.

Which is the densest stable element, about twice as dense as lead?

Osmium, at about 22.6 g/cm³, is the densest stable element, nearly twice lead's 11.3; Smithson Tennant named it in 1803 from the Greek osme, 'smell', for its pungent volatile tetroxide.

Selenium's name comes from the Greek for which celestial body?

The Moon is selene in Greek; selenium's discoverer chose the name to pair the element with its chemical cousin tellurium, which is named after tellus, Latin for the Earth.

Vanadium is named after Vanadís, a goddess of which mythology?

Vanadís is a byname of the Norse goddess Freyja; the Swede Nils Sefström chose it because the element's compounds come in so many beautiful colours.

Cadmium was discovered in 1817 as an impurity in which compound sold in German pharmacies?

Zinc carbonate sold to German apothecaries sometimes came out discoloured when heated; Friedrich Stromeyer, an inspector of pharmacies, traced the tint to a new metal and named it after cadmia, an old word for zinc ore.

Sulfuric acid was known to medieval alchemists by what name?

Oil of vitriol was the alchemists' name for sulfuric acid, H₂SO₄, made by roasting 'vitriols' such as green vitriol (iron sulfate); aqua fortis was nitric acid and spirit of salt hydrochloric.

Which compound did chemist Friedlieb Runge first isolate after Goethe handed him a box of beans to analyse?

Caffeine came out of coffee beans a Greek had sent Goethe; he gave them to the young Friedlieb Runge after watching him dilate a cat's pupil with a plant juice.

Salicin, the precursor to aspirin, comes from the bark of which tree?

Willow is Salix in Latin, which gave salicin its name; the body turns it into salicylic acid, which eased pain but upset the stomach until Bayer chemists made a gentler version, aspirin.

Which plastic, made from phenol and formaldehyde in 1907, was the first to be fully synthetic?

Bakelite resists heat and does not conduct electricity, so Leo Baekeland's resin, which he named after himself, was moulded into electrical insulators, telephones and radio cases.

Which explosive, first made by Ascanio Sobrero, is also prescribed for angina?

Nitroglycerin seemed too dangerous to use, and Ascanio Sobrero himself warned against it; in the body, though, it releases nitric oxide, which relaxes blood vessels and eases the chest pain.

Which explosive, first made in 1863, was used as a yellow dye for decades before anyone recognised its power?

TNT is so hard to set off that for almost thirty years nobody realised the yellow dye was an explosive; that same stability later made it the standard filling for artillery shells.

In gunpowder, which ingredient acts as the oxidiser?

Saltpetre, or potassium nitrate, carries its own supply of oxygen, so the sulfur and charcoal fuels can burn in an instant without air, even sealed inside a gun barrel.

The pH scale was introduced in 1909 by Søren Sørensen at which brewery's laboratory?

Carlsberg's research laboratory in Copenhagen employed Søren Sørensen as head of chemistry; he devised pH in 1909 as a simple way to express the hydrogen-ion concentration that mattered in his work on proteins.

Which word did Rudolf Clausius coin in 1865 to sound like 'energy'?

Entropy was Rudolf Clausius's new name for what he had called a body's 'transformation content'; he built it on the Greek for transformation and shaped it to echo 'energy' because he saw the two quantities as closely analogous.

Which French chemist rode a balloon above 7,000 metres in 1804 to sample the upper air?

Joseph Louis Gay-Lussac filled flasks with the thin air during the flight, and his analysis showed it held the same share of oxygen as air at ground level.

Graphene was first isolated in 2004 at which university, using adhesive tape and graphite?

Manchester physicists Andre Geim and Konstantin Novoselov peeled graphite until a flake one atom thick was left, at a time when many believed so thin a crystal could not be stable; it won them the 2010 Nobel Prize in Physics.

Buckminsterfullerene, discovered in 1985, contains how many carbon atoms?

Buckminsterfullerene's 60 carbon atoms sit like the corners of a football's panels, so its discoverers named it after Buckminster Fuller, the architect whose geodesic domes share the pattern.

Stainless steel resists rust because at least a tenth of it is which element?

Chromium in the steel reacts with oxygen to form an invisibly thin oxide film that seals the surface, so rust never gets the chance to start.

Galvanisation protects steel with a coating of which metal?

Zinc is more reactive than iron, so it corrodes first and sacrifices itself to protect the steel beneath, even where there are gaps in the coating.

Which metal's oxide formed the cathode of John Goodenough's 1980 lithium battery?

Cobalt oxide gave John Goodenough's cathode about four volts, nearly twice what the earlier lithium cell managed; the first lithium-ion batteries went on sale in 1991.

Which dating method won Willard Libby the 1960 Nobel Prize in Chemistry?

Radiocarbon dating works because a plant or animal stops taking in carbon-14 when it dies, so the amount that remains acts as a clock; Willard Libby turned the idea into a working method in 1949.

Which two chemists proved that nuclear fission had occurred, in December 1938?

Otto Hahn and Fritz Strassmann found barium where none should be after firing neutrons at uranium; Lise Meitner and her nephew Otto Frisch explained it as the nucleus splitting, yet Hahn alone got the Nobel.

Which chemist developed leaded petrol and the first CFCs, and died strangled by his own bed device?

Thomas Midgley Jr. added tetraethyl lead to petrol in 1921 and devised Freon in 1928; in 1944, paralysed by polio, he was strangled by the rope-and-pulley system he had built to lift himself from bed.

Ahmed Zewail won the 1999 Nobel Prize in Chemistry for filming reactions with ultrafast lasers, founding which field?

Femtochemistry uses laser flashes lasting femtoseconds, millionths of a billionth of a second, to catch atoms mid-reaction; the Nobel committee compared Ahmed Zewail's method to a slow-motion replay of a goal.

Frances Arnold won the 2018 Nobel Prize in Chemistry for pioneering what technique for enzymes?

Directed evolution mimics natural selection in the lab: Frances Arnold mutated enzyme genes at random and screened for improved variants over repeated rounds, a method she first demonstrated in 1993.

Dan Shechtman won the 2011 Nobel Prize in Chemistry for discovering which structures?

Quasicrystals looked impossible on 8 April 1982, when Dan Shechtman's electron microscope showed atoms packed in a pattern that never repeats; he was asked to leave his research group before others confirmed it.

Percy Julian's synthesis work laid the foundation for the industrial production of which drug?

Percy Julian's 1949 route to cortexolone (Compound S) from soybean sterols made cortisone cheap enough for mass production; he had earlier been the first to synthesise physostigmine, in 1935.

Which substance did 18th-century chemists believe every burning material gave off, until oxygen's role in combustion was understood?

Phlogiston was supposed to escape from anything that burned, but careful weighing showed that metals get heavier when they burn, not lighter, and the idea gave way to oxygen chemistry.

Helium was first detected in 1868 as a yellow spectral line in the Sun during what event?

A total solar eclipse drew Jules Janssen to India in 1868, where he recorded the unknown yellow line; Norman Lockyer concluded it came from an element not yet found on Earth and named it after helios, Greek for Sun.

Which DuPont material did Roy Plunkett find by accident in 1938, as a white solid inside a gas cylinder?

Teflon appeared when a cylinder of gas meant for making new refrigerants seemed empty yet weighed the same; Roy Plunkett opened it and found the gas had turned into a slippery white solid.

Which Swedish village gave its name to four chemical elements?

Ytterby's quarry yielded an unusual black rock in 1787, and chemists spent the next century teasing new elements out of it; yttrium, ytterbium, terbium and erbium all carry the village's name.

Dry ice, the fog-maker of stage shows and Halloween cauldrons, is the solid form of which gas?

Carbon dioxide has no liquid state at normal air pressure, so a block of dry ice turns straight to gas and leaves no puddle. Its fog hugs the floor instead of rising like smoke.

Which gas, still used by dentists as a sedative, was inhaled for fun at British 'laughing gas' parties?

Nitrous oxide can set users laughing in a brief euphoria, which made 'laughing gas parties' an upper-class craze from 1799.

Which explosive did Alfred Nobel invent in 1866 to make dangerously shock-sensitive nitroglycerin safe to handle?

Dynamite was patented the following year and quickly won wide use as a more robust alternative to black powder.

Which metal, named after the island of Cyprus, turned the Statue of Liberty green as it weathered?

Copper weathers to a green layer called verdigris. The Romans knew the metal as aes Cyprium, 'metal of Cyprus', later shortened to cuprum.

What legendary substance did medieval alchemists believe could turn base metals such as lead into gold?

Philosopher's stone was only one of its names: alchemists also called it 'the tincture' and 'the powder', with 'red lion' the code name for the gold-making kind.

Which nutrient, chemically ascorbic acid, must humans and guinea pigs get from food because they cannot make it?

Vitamin C is made by most animals, but humans, apes, monkeys and guinea pigs carry a broken gene for it. Going without causes scurvy, once a major killer of sailors.

Which compound gives chilli peppers their burn, rated on the Scoville scale, yet goes unnoticed by birds?

Capsaicin deters mammals, whose molar teeth destroy the seeds, while birds cannot feel it and scatter the seeds intact.

Which strong acid does the human stomach lining secrete to help digest food and kill swallowed microbes?

Hydrochloric acid makes human gastric juice far harsher than most animals', on a par with carrion-eating scavengers that need extra protection from pathogens.

Which gas, named from the Greek for 'to smell', forms a high-altitude layer that absorbs ultraviolet rays?

Ozone was named in 1839 by Christian Schönbein, who recognised its pungent odour as the smell that often follows a bolt of lightning.

Which temperature scale, the SI base unit, starts at absolute zero and is written without a degree symbol?

Kelvin readings are simply Celsius plus 273.15, so the scale has no negative numbers. The old name 'degree Kelvin' was dropped in the 1960s.

Which sugar, a pairing of glucose and fructose, is refined from cane and beet as ordinary table sugar?

Sucrose comes out as the same molecule whether it is crushed from sugarcane in the tropics or processed from sugar beet in temperate climates.

Which gas, first collected from the marshes of Lake Maggiore in 1776, is the main constituent of natural gas?

Methane is odourless, so the familiar smell of household gas comes from an odorant added as a safety measure to make leaks noticeable.

Which odourless gas from faulty heaters and car exhausts kills by latching onto haemoglobin in the blood?

Carbon monoxide is non-irritating at first, so victims get no warning. That is why homes with gas appliances are fitted with detectors.

Which acid, first isolated in 1671 by distilling large numbers of ants, is named after the Latin for ant?

Formic acid is what wood ants spray at prey and at anything threatening the nest. An English naturalist was the first to describe collecting it.

Which acid mixture, able to dissolve gold, did George de Hevesy use to hide two Nobel medals from the Nazis?

Aqua regia, Latin for 'royal water', kept the gold dissolved on a laboratory shelf throughout the war. It was later recovered and returned to the Nobel Foundation.

Which bright yellow element was known for centuries as brimstone, the 'burning stone' of the Bible?

Sulfur rains down as 'brimstone and fire' on Sodom and Gomorrah in Genesis, yet the pure yellow solid has no smell at all.

Limestone, chalk and marble are all compounds of which metal, also the most abundant metal in the human body?

Calcium takes its name from calx, the Latin for lime, which the Romans made by heating limestone for their mortar.

Which metal burns with a brilliant white light and lit up early flash photography and marine flares?

Magnesium also sits at the centre of every chlorophyll molecule, so plants cannot photosynthesise without it.

Which radioactive element, first made at Berkeley in 1950, is named after its home state and university?

Californium is such a strong neutron emitter that a single microgram throws out 2.3 million neutrons a second, enough to help start up nuclear reactors.

Which Swedish village with an old feldspar mine gave its name to four elements, including terbium and erbium?

Ytterby also lent its name to yttrium and ytterbium, and several more elements were first found in minerals from the same mine.

Which radioactive element, named from the Greek for 'unstable', is the rarest found naturally in Earth's crust?

Astatine exists only as a fleeting decay product of heavier elements, so no more than a trace of it is present in the crust at any given time.

Which group of elements, whose name means 'salt former', includes chlorine and iodine?

Halogens earn the name by reacting with metals to produce a wide range of salts, potassium iodide among them.

What name is given to the horizontal rows of the table of elements, whose members share a number of electron shells?

Periods run across the table, and each new one begins when a fresh electron shell starts to fill.

What term describes the electrons in an element's outermost shell, the ones that take part in chemical bonding?

Valence electrons explain the layout of the periodic table: an element's column tells you how many of them it has, which is why neighbours in a column react alike.

In a cup of sweet tea, what is the chemistry term for the sugar, the substance that gets dissolved?

Solute is the part that dissolves and the solvent does the dissolving. In an equal mix of two liquids the labels stop meaning much.

What name is given to the solid that forms and settles out when two clear solutions react?

Precipitate appears when a dissolved compound's concentration exceeds its solubility. Chemists weigh it to identify and measure ions.

Which technique separates liquids by boiling and condensing them, as in making whisky or refining crude oil?

Distillation in a traditional pot still remains the way fine spirits such as cognac, tequila and rum are made.

Which lab technique finds an unknown concentration by adding a known solution until an indicator changes colour?

Titration takes its name from the French titre, which began as a measure of the fineness of the gold in coins.

Which dye mixture, extracted from lichens, turns red in acids and blue in alkalis?

Litmus was already being used to study acids and bases around 1300, by the Catalan physician Arnaldus de Villa Nova.

Which lab indicator, used for over a century as a laxative, turns from colourless to pink in a basic solution?

Phenolphthalein had its laxative effect discovered by accident around 1900, when Hungary's government tried using it as a marker in wine.

What is the chemical name for burning, the reaction that powers candles, campfires and petrol engines?

Combustion does not always mean fire: a flame is only visible when the substance that is burning vaporises.

Which process, used in brewing and bread-making, has yeast convert sugars into ethanol?

Fermentation was famously summed up in 1876 as 'la vie sans air', life without air, and people had been using it for millennia before anyone knew yeast was alive.

What is the name of the reaction in which lye breaks fats and oils down into soap and glycerol?

Saponification can also happen to the fat of a buried body, turning it into a waxy substance often called 'grave wax'.

Which property of carbon-14, about 5,730 years long, lets carbon dating put an age on ancient bones and timber?

Half-life stays the same however much of the sample is left. The original name, 'half-life period', was shortened in the early 1950s.

What is the common name for deuterium oxide, the D2O used inside some nuclear reactors?

Heavy water is 10.6% denser than the ordinary kind and has a higher melting point. In very large doses it is even toxic.

Which gas, a natural plant hormone that ripens fruit, is also the raw material of the most widely used plastic?

Ethylene is linked into long chains to make polyethylene, a job that takes the majority of the world's supply of the gas.

Which DuPont fibre debuted in toothbrush bristles in 1938 before causing a sensation as women's stockings?

Nylon stockings sold 64 million pairs in their first year on the market, then almost all production was diverted to wartime parachutes.

Which process for toughening rubber, patented by Charles Goodyear in 1844, is named after the Roman god of fire?

Vulcanization came to Goodyear in 1839, when a rubber mixture heated over a hot stove became rigid. Until then, rubber goods kept turning sticky and being sent back.

What term describes a blend of mercury with another metal, the basis of traditional dental fillings?

Amalgam made with gold is used to pull the precious metal out of its ore, though a few metals, such as platinum and tantalum, refuse to blend with mercury at all.

Which property measures a liquid's resistance to flow, making syrup pour far more slowly than water?

Viscosity falls to zero only in superfluids at very low temperatures. Every ordinary fluid has at least a little.

What type of mixture are milk and vinaigrette, with tiny droplets of one liquid spread through another?

Emulsion comes from the Latin emulgere, 'to milk out', because milk is the classic case of fat held in water.

Which conical lab flask, invented by a German chemist in 1860, has a narrow neck so liquids can be swirled safely?

Erlenmeyer flasks are named after their inventor, Emil Erlenmeyer, and their narrow necks double as a holder for filter funnels.

Which English scientist, the first to describe colour blindness, laid the foundations of modern atomic theory?

John Dalton studied his own faulty colour vision, and the condition is still known as Daltonism in several languages.

Which New Zealand-born winner of the 1908 chemistry Nobel discovered the nucleus with the gold foil experiment?

Ernest Rutherford did not run the experiment himself: Hans Geiger and Ernest Marsden performed it, and he worked out what the surprising scattering meant.

Which Italian scientist invented the first electric battery and gave his name to the unit of electric potential?

Alessandro Volta so impressed Napoleon Bonaparte with his invention that he was invited to demonstrate it at the Institute of France.

Which English scientist identified 'inflammable air' in 1766 and later ran an experiment to measure Earth's density?

Henry Cavendish later showed that his inflammable air, now called hydrogen, produces pure water when it burns.

Which British chemist, the 1964 Nobel laureate for X-ray maps of molecules, once taught Margaret Thatcher?

Dorothy Hodgkin solved the structure of penicillin in 1945, and Thatcher later hung her old tutor's portrait in Downing Street.

Which ancient Greek, nicknamed the 'laughing philosopher', taught that matter is made of tiny indivisible bodies?

Democritus earned the nickname for his emphasis on cheerfulness, and was said to laugh at the empty ambition of human beings.

Which Dutch scientist won the very first Nobel Prize in Chemistry in 1901 for his work on solutions?

Jacobus van 't Hoff regarded the prize as the culmination of his career. He had also co-founded the first journal dedicated to physical chemistry.

Which compound, made by soil bacteria, gives beetroot its earthy taste and rain its fresh-earth smell?

Geosmin is part of petrichor, the scent released when rain falls after a dry spell. Beets, unusually, make their own supply.