50 Fun Facts About Sodium

Sodium, element 11, comes just after which noble gas?

Neon: sodium's eleventh electron sits alone in an outer shell and is lost with great ease, which is why the metal reacts so fiercely and never occurs free in nature.

Which chemical symbol stands for sodium?

Na, from the Latin name natrium, which goes back to a soda salt gathered from dry lake beds in the ancient world; German, Dutch and the Scandinavian languages still call the element Natrium.

Eating too much sodium over the years is most strongly linked to which condition?

High blood pressure: sodium makes the body hold on to water, and the extra fluid pushes harder on vessel walls, raising the risk of heart disease and stroke.

Who first isolated sodium metal in 1807?

Humphry Davy ran current from a powerful battery through a molten compound at London's Royal Institution in October 1807, just as he had done shortly before to free potassium.

Which Swedish chemist devised today's letter symbols for the elements, publishing sodium's in 1814?

Jons Jakob Berzelius abbreviated each element's Latin name to one or two letters, which is why several symbols, sodium's among them, look nothing like their English names.

How is bulk sodium metal usually stored?

Under oil or an inert gas, because bare sodium tarnishes within seconds in air and reacts violently with moisture; the metal is soft enough to cut with a knife.

What colour does sodium give to a flame?

Yellow: the glow is so strong that a trace of sodium can drown out other metals' colours, so chemists view flame tests through blue cobalt glass to filter it out.

Which German physicist gave sodium's 'D' line its letter in 1814 while mapping dark lines in sunlight?

Joseph von Fraunhofer lettered the boldest of the hundreds of dark lines he charted; decades later Kirchhoff and Bunsen matched his D line to sodium, showing that the Sun holds earthly elements.

What does a lump of sodium metal do when dropped into a bowl of water?

Floats and fizzes about: sodium is slightly less dense than water, so it stays on the surface while it reacts violently. Only lithium and potassium are lighter metals.

Sodium is forged inside massive stars when two nuclei of which element fuse, once their helium is spent?

Carbon: two carbon nuclei merge at hundreds of millions of degrees and shed a proton, leaving sodium. The Sun is far too small ever to burn carbon this way.

Sodium, the sixth most abundant element in Earth's crust, is the commonest of which family?

Alkali metals: sodium makes up more than 2% of the crust, yet it is so reactive that none of it occurs as free metal; it is all locked in minerals such as feldspar.

Sodium metal melts at about the temperature of what?

Boiling water: sodium melts at about 98 °C because each atom lends only one electron to the bonds holding the metal together. Its heavier cousin caesium melts at about 28 °C.

What two products form when sodium metal reacts with water?

A hydroxide and hydrogen gas: the heat can set the hydrogen alight, and high-speed film suggests the blast begins when the metal sheds electrons so fast that its surface bursts apart.

Squeezed to millions of atmospheres of pressure, sodium metal becomes what?

A clear transparent solid: the pressure forces sodium's free electrons into the gaps between its atoms, so the shiny metal stops conducting and lets light pass through like glass.

Sodium metal is made by passing electricity through molten table salt, which also releases which gas?

Chlorine: the current splits salt into its two elements in a Downs cell, where iron baffles keep the molten sodium and the gas apart so they cannot recombine.

Metallic sodium was first made commercially in the 19th century as a step in producing which other metal?

Aluminium: in Deville's process sodium stripped the metal out of its salts, until the Hall-Héroult electric process made aluminium cheap and ended the demand for sodium.

Sodium's alloy with potassium is notable for being what at room temperature?

A liquid: each metal is solid on its own, yet the right mix stays runny down to about −12 °C, so it is pumped through pipes as a coolant that will not freeze.

Molten sodium is used as the coolant in which type of nuclear power plant?

Fast neutron reactors: sodium's high boiling point lets them run hot at ordinary pressure, but the coolant burns in air and reacts violently with water, so any leak is a serious hazard.

Idaho's EBR-I, cooled by a sodium-potassium alloy, became in 1951 the first nuclear reactor to do what?

Generate electricity: on 20 December 1951 its output lit four light bulbs, and it later powered its whole building. It was built to test whether a reactor could breed more fuel than it burned.

In high-performance engines, sodium is sealed inside which component to carry heat away?

Poppet valve stems: the sodium melts inside the hollow exhaust valve and carries heat from the scorching valve head up to the cooler stem.

Highly efficient low-pressure sodium lamps spent decades lighting what?

City streets: the lamps turn electricity into light very efficiently, but nearly all of it is a single wavelength, so objects beneath them lose their colours and look alike.

Astronomers fire lasers at a layer of sodium atoms 90 km up to create an artificial what?

Star: the sodium, shed by meteors burning up, glows where the beam strikes it, giving telescopes a reference point they use to cancel out the blurring of turbulent air.

Sodium has been detected in the thin exospheres of the Moon and which planet?

Mercury has no true atmosphere, only a thin haze of atoms blasted off its surface by the solar wind and meteoroids. Sunlight then pushes some of them into a faint comet-like tail.

Rock salt is the everyday name for which mineral, the natural form of table salt?

Halite forms thick beds where ancient seas dried up. Buried deep, the salt can slowly flow, pushing up through the rock above as salt domes that often trap oil.

Since the 1920s, table salt has commonly been fortified with which element to prevent goitre?

Iodine: the thyroid needs it to make its hormones, and without enough the gland swells into a goitre. Switzerland began adding it to salt in 1922 and the United States followed in 1924.

Most of the sodium in the American diet comes from which source?

Packaged and restaurant food supplies more than 70% of it, so the salt shaker is only a minor player. Bread and cold cuts are among the biggest contributors.

The sodium-potassium pump pushes three sodium ions out of a cell using one molecule of which energy carrier?

ATP: each molecule buys three sodium ions out and two potassium ions in, and the pumps work so constantly that at rest they burn about a third of all the ATP the body makes.

Which part of the body decides how much sodium to keep and how much to shed?

The kidneys strain sodium out of the body's fluids and then take most of it back. When pressure or sodium runs low, hormones such as aldosterone tell them to reclaim even more.

The sudden inflow of sodium ions into a nerve cell through voltage-gated channels produces what?

An action potential: sodium flooding in flips the cell's charge for about a thousandth of a second, and the spike races along the nerve. Lidocaine numbs by blocking those channels.

Marathon runners risk hyponatremia, a dangerous sodium imbalance, by doing too much of what?

Drinking water faster than the body can shed it dilutes the sodium in its fluids below about 135 mmol/L. Water then seeps into cells and swells them, which is most dangerous in the brain.

What is the common name for sodium bicarbonate?

Baking soda releases bubbles of gas when it meets an acid such as vinegar or is heated, and they make batter rise. Britain and Australia call it bicarbonate of soda.

Sodium hydroxide, or lye, is used to make which everyday product from fats and oils?

Soap: lye splits fats into soap and glycerol, a reaction called saponification. Sodium lye gives firm bars, while potash lye gives soft soap.

Washing soda got the name 'soda ash' because it was historically extracted from what?

The ashes of salt-tolerant plants such as saltwort and seaweed supplied Europe's soda until factories took over, after Nicolas Leblanc patented a way to make it from common salt.

The Solvay process for soda ash and the Solvay physics conferences are named after a chemist of which nationality?

Belgian industrialist Ernest Solvay grew rich on his ammonia-soda process and spent part of the fortune on science, funding the 1911 conference that gathered Einstein, Marie Curie and Rutherford.

The ancient Egyptians used natron, a natural sodium salt, for what purpose?

Mummification: embalmers covered the body in natron until it dried out, because the salt draws out the moisture that decay needs.

Sodium azide was long the gas-forming compound in which safety device?

Car airbags: a crash sensor fires the azide, which bursts into nitrogen gas and fills the bag within a few hundredths of a second. The powder is highly toxic, so newer inflators use other propellants.

Chemist Kikunae Ikeda, who invented MSG after studying kombu broth in 1908, gave its savoury taste which name?

Umami: Ikeda patented the seasoning, and in 1909 it went on sale as Ajinomoto, 'essence of taste', still the name of the company that makes it.

Which English word for regular pay comes from the Latin for salt?

Salary comes from Latin salarium, built on sal, 'salt'. It is said to have begun as a soldier's allowance for buying salt, but the popular claim that legionaries were paid in salt itself has no ancient support.

Who led the 1930 Salt March to the sea at Dandi?

Mahatma Gandhi walked to the coast and picked up natural salt from the shore, a technical breach of the salt laws that set off mass civil disobedience and some 60,000 arrests.

The Wieliczka Salt Mine, with chapels carved from rock salt, is in which country?

Poland: Wieliczka, near Kraków, was a royal mine worked without a break from the 13th century to the late 20th, and it was the miners themselves who carved its chapels and statues out of the salt.

Demand for sodium metal fell after 1970 when which product it helped make was phased out?

Leaded gasoline: its anti-knock additive, tetraethyl lead, was made by reacting a sodium-lead alloy, so a major market for the metal vanished as unleaded fuel took over.

After a nuclear criticality accident, doctors gauge a victim's neutron dose from radioactive sodium in which body fluid?

Blood: neutrons turn a little of its ordinary sodium into sodium-24, which gives off gamma rays with a half-life of about 15 hours, so the more of it doctors find, the larger the dose.

Sodium fluoride is added to many toothpastes to help prevent what?

Cavities: the fluoride builds into the enamel as a tougher mineral that mouth acids dissolve less easily, and many towns add a trace to their tap water for the same reason.

Rock salt is spread on winter roads because it does what to water?

Lowers its freezing point: the salt dissolves into the thin film of water on ice and makes a brine that stays unfrozen well below 0 °C, so the ice keeps melting.

Most of the sodium dissolved in the oceans originally came from where?

Rocks on land: slightly acidic rain leaches sodium out of them and rivers carry it to the sea, where it builds up because sea life removes little of it.

The poison of which fish, served in Japan as fugu, kills by blocking the sodium channels in nerves?

Pufferfish carry tetrodotoxin, which plugs the channels that let sodium into nerve cells. Signals stop, and the muscles used for breathing are paralysed.

Sodium polyacrylate, a powder that soaks up hundreds of times its weight in water, is the absorbent in which product?

Disposable diapers: the powder swells into a gel that holds on to moisture instead of leaking it back, which let makers replace thick fluffy padding with thin cores.

Sodium hypochlorite dissolved in water is sold as which household product?

Bleach: the compound oxidises stains into colourless substances, and it must never be mixed with ammonia or acidic cleaners, because the reaction gives off toxic gases.

Pink 'Himalayan' salt is mined mainly in which country?

Pakistan: the salt comes from the Salt Range in Punjab, well south of the Himalayas, chiefly from the huge Khewra mine. Traces of other minerals give it the pink tint.

Which sodium mineral did twenty-mule teams haul out of Death Valley in the 1880s?

Borax: teams of eighteen mules and two horses dragged it 165 miles across the desert to the railway, and the image lived on as the 20 Mule Team brand of laundry powder.