50 Fun Facts About Helium

What is helium's atomic number?

Its symbol is He, and it heads the noble gas column of the periodic table.

Helium takes its name from the Greek word for what?

It was named after an unknown yellow line spotted in the solar spectrum in 1868, decades before anyone found it on Earth.

To which group of the periodic table does helium belong?

It is the first member of the group and, after neon, the second least reactive element of all.

Roughly what share of the ordinary matter in the universe is helium, by mass?

Only hydrogen is more abundant; helium outweighs all the heavier elements put together more than 12 times over.

During what event was helium first detected in sunlight, in 1868?

Jules Janssen recorded the bright yellow line at Guntur, India, and it was at first assumed to be sodium.

Which English astronomer proposed the yellow D3 line was a new element and named it?

The '-ium' ending is odd because it is normally reserved for metals; the astronomer probably did not know the chemists' convention.

Who first detected helium on Earth, in 1881, in material from an eruption of Mount Vesuvius?

He recognised the D3 spectral line in the sublimated volcanic material.

Which Scottish chemist isolated helium on Earth in 1895 by treating the mineral cleveite with acids?

He had been looking for argon, and had planned to call the new gas krypton, a name he later reused for another noble gas.

Cleveite, the ore from which helium was first isolated, is a variety of which uranium mineral?

Uranium and thorium minerals hold helium because their alpha particles are helium nuclei that grab electrons once they stop in the rock.

Which pair showed in 1907 that alpha particles are helium nuclei using thin glass and an evacuated tube?

A discharge in the tube revealed the tell-tale spectrum of the gas that had built up inside.

Who first liquefied helium, in 1908?

He got it below 5 K but could not freeze it; his student Willem Keesom finally solidified a cubic centimetre in 1926 using extra pressure.

What is unique about helium at atmospheric pressure as it approaches absolute zero?

Its zero-point energy is too high to allow a solid; you need about 25 atmospheres of pressure to freeze it.

Below roughly what temperature does helium liquefy at atmospheric pressure?

That is the lowest boiling point of any element; nitrogen, by comparison, boils at 77 K.

Who discovered in 1938 that helium-4 loses almost all viscosity near absolute zero, now called superfluidity?

The same effect was seen in helium-3 in 1972 at far lower temperatures, work that earned a 1996 Nobel Prize.

What is the superfluid phase of liquid He-4 below the lambda point called?

Its thermal conductivity is a million times that of ordinary liquid helium and several hundred times that of copper.

What is the thin layer of superfluid helium that creeps up and over the walls of its container called?

It is about 30 nanometres thick regardless of the surface, and lets helium II escape any unsealed vessel to somewhere warmer.

Heat travelling through helium II as a wave at about 20 m/s is known as what?

Waves on the creeping surface film, restored by van der Waals force rather than gravity, are called third sound.

Why does inhaling helium make a voice go squeaky?

The vocal folds vibrate at the same pitch; it is the resonances of the vocal tract that shift upward, changing the timbre.

Inhaling which dense gas produces the opposite effect to helium, deepening the voice?

Xenon works too; both slow the speed of sound and lower the vocal tract's resonant frequencies.

What is the main danger of inhaling too much helium?

Breathing straight from a pressurised cylinder is worse still, as the pressure can rupture lung tissue.

What is the largest single use of helium?

Balloons are the best-known use but a minor one; cryogenic cooling of superconducting magnets took about a third of world supply in 2014.

How much liquid helium does the Large Hadron Collider use to keep its magnets at 1.9 K?

That is colder than deep space, which sits at about 2.7 K.

What is helium's concentration in Earth's atmosphere?

It stays low despite constant production underground because it escapes into space, making it a non-renewable resource.

Most of the helium on Earth is created by what process?

Around 3,000 tonnes a year form this way in the lithosphere, and much of it gets trapped underground.

From what source is commercial helium extracted?

Some gas fields hold more than 7% helium; extracting it from air, where it is 5 ppm, is not economical.

A 1903 gas geyser that would not burn revealed helium in a drilling well. Where was it?

Kansas geologist Erasmus Haworth found the gas was 72% nitrogen and 15% methane; further analysis showed 1.84% helium.

Where did the US government set up the National Helium Reserve in 1925?

The Cliffside gas field nearby stored a helium-nitrogen mix piped 425 miles from Bushton, Kansas.

Why did German Zeppelins such as the Hindenburg use hydrogen instead of helium?

America held a production monopoly at the time, and the gas was prohibitively expensive anyway.

What was the world's first helium-filled airship?

It flew from Hampton Roads, Virginia, to Washington, D.C., on 1 December 1921, nearly two years before the rigid USS Shenandoah.

Which country overtook Qatar in 2024 to become the world's largest helium producer?

The US extracted 68 million standard cubic metres that year against Qatar's 64 million.

The Helium Privatization Act of 1996 told which department to empty the National Helium Reserve?

By 1995 the reserve held a billion cubic metres of gas and was US$1.4 billion in debt.

A 54-billion-cubic-foot helium deposit was found in 2016 in which African country?

Algeria, meanwhile, had become the world's second-largest producer after opening plants at Arzew and Skikda.

Which company bought the remnants of the US National Helium Reserve on 27 June 2024?

Congress had ordered the reserve emptied back in 1996, when it was US$1.4 billion in debt.

How many isotopes of helium are stable?

Helium-3 and helium-4; the atmosphere holds one atom of the lighter one for every million of the heavier.

Which body's surface holds helium-3 at 10 parts per billion, prompting fusion-fuel mining ideas?

Solar wind bombards the regolith with the isotope; Gerald Kulcinski proposed mining it in 1986.

How long after the Big Bang was most of the universe's helium formed?

The tightly bound helium-4 nucleus soaked up almost all the free neutrons, which is why so little lithium, beryllium or boron was made.

What were the first molecular bonds in the universe, formed when primordial helium combined with protons?

HeH+ is the strongest Bronsted acid known and will protonate anything it touches.

Helium is used instead of cheaper argon as a welding shield gas for which kind of materials?

It also protects silicon and germanium crystals as they are grown for electronics.

Deep divers breathe helium mixtures such as trimix and heliox mainly to avoid what?

Helium has no narcotic effect, and its low density makes breathing easier at depth, though below 150 metres divers can get tremors from high-pressure nervous syndrome.

Helium-neon lasers, once common in barcode readers and pointers, produce a beam of what colour?

They were almost universally replaced by cheaper diode lasers.

Roughly how much helium did each Saturn V launch require?

Rockets use it to backfill propellant tanks in flight and to purge fuel lines before launch.

Which Nobel laureate argued in 2010 that helium's price should rise 20-fold to stop waste such as party balloons?

He had shared the 1996 physics prize for discovering superfluidity in helium-3.

Helium diffuses through solids about three times faster than air. Which industrial job does that suit?

A helium mass spectrometer can sniff out leaks as small as a billionth of a millibar-litre per second.

What is the principal impurity left in Grade-A helium after purification?

Activated charcoal is the final purification step, yielding 99.995% pure gas.

In April of which year was helium approved for medical use in America, for humans and animals?

The approval covered both humans and animals; the gas plays no biological role and is non-toxic.

In which Indian town did Jules Janssen observe the first evidence of helium during the 1868 eclipse?

The bright yellow line at 587.49 nanometres was at first assumed to be sodium.

Why is helium's '-ium' ending considered unusual?

Lockyer, an astronomer, was probably unaware of the chemists' naming conventions.

Which country's navy sponsored three small experimental helium plants during World War I?

The idea followed a suggestion by Sir Richard Threlfall.

Why are Styrofoam floats often used with liquid helium I?

Its gas-like refractive index of 1.026 makes the liquid's surface extremely hard to see.

Roughly what fraction of world helium production goes to cryogenics, its largest single use?

The main commercial application is cooling the superconducting magnets in MRI scanners.