40 Fun Facts About Alkali Metals

Which soft drink was sold in the early 1930s as a Lithiated Lemon Soda, claiming to contain a lithium salt?

7UP's early labels read 7up Lithiated Lemon Soda and claimed it contained lithium citrate, a mood-stabilising salt. The word was dropped from the name later in the 1930s.

An informal unit of radiation dose is named after which fruit, a nod to the radioactive potassium-40 inside?

Banana equivalent dose compares a radiation exposure with eating one banana, because about 0.012% of all natural potassium is the unstable isotope potassium-40.

Sodium and its fellow alkali metals are so soft that chemists routinely slice them at room temperature with what?

A knife slices through any alkali metal, exposing a shiny surface that dulls rapidly as the metal reacts with the air around it.

Sodium, a metal that reacts violently with water, combines with which poisonous gas to form ordinary table salt?

Chlorine and sodium are each hazardous alone, yet bonded together they make the seasoning on every dinner table. Salt is about 39% sodium by weight.

Sodium's symbol Na comes from natron, a salt mixture that ancient Egyptians used as a drying agent in which practice?

Mummification relied on natron to draw the water out of a body before it was wrapped. Its Latin form, natrium, is why sodium's symbol looks nothing like its English name.

On which NASA Moon mission did the crew improvise a fix so lithium hydroxide canisters could keep scrubbing their air?

Apollo 13's astronauts relied on lithium hydroxide to absorb the carbon dioxide they breathed out, so command-module cartridges had to be adapted to work in the lunar module.

Since 1967, radiation from caesium-133 atoms has officially defined which basic unit of measurement?

The second is defined as exactly 9,192,631,770 cycles of the radiation given off by caesium-133 atoms, the beat that atomic clocks count.

Dropping an alkali metal such as sodium into water releases which flammable gas, which can ignite with a pop?

Hydrogen is given off as the metal tears water molecules apart, and the heat of the reaction is often enough to set the gas alight. The heavier the alkali metal, the fiercer the reaction.

Which American grunge band scored a 1990s hit with a song named after lithium, the metal used as a mood stabiliser?

Nirvana's Lithium, written by Kurt Cobain for the album Nevermind, tells of a grieving man who turns to religion as a last resort to keep himself going.

Because alkali metals react so readily with air, laboratories usually store lumps of them submerged in which liquid?

Mineral oil seals the metal off from oxygen and moisture. Rubidium and caesium are so reactive that they must be kept away from air even under it.

Alkali metals are so reactive because each atom readily loses the lone what orbiting in its outermost shell?

Electron loss leaves each atom as an ion with a charge of +1, and alkali metals let go more easily than any other elements in their rows of the periodic table.

The alkali metals fill most of which column of the periodic table, on the far left-hand side?

Group 1 only got that name in 1988; before then chemists labelled the alkali metals' column group IA.

Which English chemist was the first to isolate both potassium and sodium, announcing the two new metals in 1807?

Humphry Davy freed both metals in the same year, then isolated calcium, strontium, barium and magnesium the following year with the same approach.

Potassium in 1807 became the first metal ever isolated by which technique, made possible by the new voltaic pile?

Electrolysis of molten caustic potash freed the potassium, and the same method produced sodium later that year.

Lithium takes its name from the Greek word for what, because it was first found in an ore?

Stone, or lithos, set lithium apart from potassium and sodium, which were first known from plant and animal material rather than from rock.

Lithium was first detected in 1817 in petalite, an ore found on the island of Utö in which country?

Sweden's Johan August Arfwedson spotted the new element while analysing the ore, though he tried and failed to isolate the pure metal.

Lithium, element number three, holds which record among all the metals of the periodic table?

Least dense of all the metals, lithium weighs about half as much as the same volume of water, so a lump floats while it fizzes.

Lithium is one of the few elements whose first atoms were forged in the aftermath of which cosmic event?

The Big Bang produced lithium-7 before any star existed, yet the amount astronomers measure does not match the theory, a puzzle called the cosmological lithium problem.

Lithium salts have been prescribed since the mid-twentieth century as a mood stabiliser, chiefly for which condition?

Bipolar disorder, once known as manic depression, has been lithium's approved use in the United States since 1970 and remains its main use there.

The 2019 Nobel Prize in Chemistry went to three scientists who used lithium to develop which everyday technology?

Rechargeable batteries built around lithium ions power phones, laptops and electric cars; Stanley Whittingham, John Goodenough and Akira Yoshino shared the prize.

Salar de Uyuni, the world's largest salt flat and a vast store of lithium, lies in which South American country?

Bolivia's Salar de Uyuni sits on a pool of lithium-rich brine and doubles as a breeding ground for three species of flamingo.

A pinch of table salt sprinkled into a flame makes it glow which colour, thanks to the sodium?

Yellow light from sodium is so pure that low-pressure sodium street lamps give off almost nothing else, which washes the colour out of everything they light.

Potassium compounds heated in a laboratory flame are recognised by which colour?

Lilac flames also appear when potassium metal meets water, because the reaction gets hot enough to ignite the gas it gives off.

Rubidium takes its name from the Latin for which colour, after the bright lines its discoverers saw?

Deep red lines in the light of a heated lepidolite sample gave the element away in 1861, and rubidus, the Latin for that shade, supplied the name.

While the other stable alkali metals are silver-coloured, pure caesium has a pale tint of which colour?

Gold is the tint of pure caesium, one of only three clearly coloured metals alongside copper and gold itself. It also melts at just 28.5 °C, so the warmth of a hand would turn it liquid.

Which French physicist, once Marie Curie's assistant, discovered francium in 1939 and named it after her homeland?

Marguerite Perey became the first woman elected to the French Académie des Sciences in 1962, as a corresponding member, after it had turned Curie herself down.

Francium is so unstable that its longest-lived form has a half-life of only about how long?

22 minutes is all it takes for half of any francium-223 to decay, and the heat of that decay would instantly vaporise any lump large enough to see.

In 1995, physicists chilled rubidium atoms to near absolute zero to create the first example of which state of matter?

Bose–Einstein condensate had been predicted seventy years earlier by Albert Einstein; Eric Cornell and Carl Wieman made it by cooling about two thousand rubidium atoms to a whisker above absolute zero.

Which German chemist discovered both caesium and rubidium with the physicist Gustav Kirchhoff in the early 1860s?

Robert Bunsen found them by studying the coloured light of heated samples in the clean, hot flame of the gas burner that carries his name.

Caesium in 1860 became the first element ever discovered using which instrument, invented only a year earlier?

Spectroscope readings showed lines no known element produced, and it took 44,000 litres of German spring water to yield a few grams of the new metal's salts.

Which baked snack is traditionally dipped in a sodium hydroxide solution, also called lye, to crisp its crust?

Pretzels are glazed with lye before they go in the oven, and the same caustic chemical is used to soften olives.

Caesium-137 from which 1986 power plant disaster left some Scandinavian reindeer over legal limits decades later?

Chernobyl's caesium-137 drifted across Europe on the wind, and with a half-life of about 30 years it takes generations to fade from soil and grazing animals.

Potassium takes its name from a substance traditionally made by soaking what in water inside a pot?

Wood ashes were valuable enough that the first US patent of any kind, issued in 1790, covered an improved way of turning them into potash.

The slow decay of potassium-40 inside rocks produces which noble gas, letting geologists date ancient lava flows?

Argon trapped in volcanic rock works as a clock, and the same decay is why the gas is relatively plentiful in Earth's atmosphere.

The word alkali, like alcohol and algebra, entered European languages from which language?

Arabic al-qali referred to the burnt remains of saltwort, a plant that was the original source of alkaline substances.

A sudden rush of sodium ions through tiny channels lets which parts of the body carry electrical signals?

Nerves rely on it so heavily that their cells can spend up to 70% of their energy pumping sodium out and potassium back in, ready to fire again.

Which 1954 US bomb test at Bikini Atoll was 2.5 times bigger than predicted because of an overlooked lithium reaction?

Castle Bravo's designers assumed its lithium-7 was inert; it was not, and the 15-megaton blast became the most powerful device the United States has ever detonated.

Which British TV show faked its bathtub explosions of rubidium and caesium by swapping the metals for hidden explosives?

Brainiac: Science Abuse found the real reaction was not particularly spectacular, so the crew blew up the bath with explosives and passed it off as the work of the metals.

Australian psychiatrist John Cade discovered lithium's calming effect in 1948 after injecting it into which animals?

Guinea pigs given a lithium solution, meant only as a control, became unusually restful, which led Cade to try the salt on his patients.

Which chemist published the symbol Na for sodium in 1814 as part of a new system of letters for the elements?

Jöns Jacob Berzelius took Na from natrium, the element's Latin name, and his letter-based notation is the one chemists have used ever since.