50 Fun Facts About Helium

What is helium's atomic number?

2: helium's atoms are so light that the gas floats in air, which is why it fills party balloons, weather balloons and airships.

Helium takes its name from the Greek word for what?

The Sun, helios in Greek, gave helium its name because astronomers saw the element's yellow line in sunlight in 1868, decades before anyone found it on Earth.

To which group of the periodic table does helium belong?

The noble gases are helium's family, and it is so unreactive that chemists have never made an ordinary stable compound of it.

By mass, about how much of the universe's ordinary matter is helium?

About 25%: almost all of that helium was made in the Big Bang itself, before any star had formed.

During what event in 1868 was helium's yellow spectral line first detected?

A total solar eclipse over India let French astronomer Jules Janssen record a bright yellow line that was at first taken for sodium.

Which English astronomer named helium after spotting its yellow line in 1868?

Norman Lockyer found the yellow line matched no known element and proposed a new one, 27 years before anyone held a sample of it on Earth.

Helium was first reported on Earth in material from which Italian volcano?

Mount Vesuvius: physicist Luigi Palmieri was analysing what the erupting volcano gave off when he spotted helium's yellow spectral line, more than a decade before anyone isolated the gas.

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

William Ramsay was hunting for argon in minerals when cleveite gave off a gas whose spectrum matched the yellow line astronomers had logged 27 years before.

Aging stars fuse three helium nuclei together to make which element?

Carbon forms when three helium nuclei fuse in an aging star's core, and that process is the main origin of the carbon in our bodies.

Which pair proved alpha particles are helium nuclei by trapping them in a glass tube?

Ernest Rutherford and Thomas Royds let alpha particles pass through a thin glass wall into a sealed tube, then sparked the trapped gas and saw helium's spectrum.

Who first liquefied helium, in 1908?

Heike Kamerlingh Onnes used his new liquid helium three years later to chill mercury, and watched its electrical resistance vanish: the discovery of superconductivity.

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

It stays liquid and never freezes because its light atoms keep jiggling even near absolute zero; only squeezing it to about 25 atmospheres will make it solid.

Helium boils at about 4 degrees on which temperature scale?

Kelvin counts up from absolute zero, and helium boils barely 4 degrees above it, lower than any other element, which is why it chills superconducting magnets.

Who discovered that liquid helium loses almost all viscosity near absolute zero, now called superfluidity?

Pyotr Kapitsa watched chilled liquid helium slip through the narrowest gaps with no measurable friction, a finding that earned him a share of the 1978 physics Nobel.

What name do physicists give the superfluid phase of liquid helium?

Helium II appears when ordinary liquid helium, called helium I, is chilled past the 'lambda point', so named because a graph of the transition traces the Greek letter lambda.

Left in an open cup, superfluid helium does what that no ordinary liquid can?

Climbs the walls and escapes: with no friction to hold it back, a thin film of superfluid helium creeps up the sides and over the rim, against gravity.

In superfluid helium, the wave that physicists call 'second sound' carries what?

Heat normally seeps slowly through a material, but in superfluid helium it travels as a wave, much as sound does, which is how second sound got its name.

Why does inhaling helium make a voice go squeaky?

Sound travels faster through it, so the throat's resonances shift upward, yet the vocal cords keep vibrating at their usual pitch.

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

Sulfur hexafluoride is about five times as dense as air, so it lowers the throat's resonances and the voice drops.

What is the main danger of inhaling too much helium?

Asphyxiation, since it displaces oxygen, is the risk, and a pressurised cylinder adds another: the blast of gas can tear lung tissue, so never inhale from one.

Hospitals rely on liquid helium to cool which machines?

MRI scanners use superconducting magnets, which carry their huge currents only when bathed in liquid helium a few degrees above absolute zero.

Which giant machine uses superfluid helium to keep its magnets colder than outer space?

The Large Hadron Collider chills its magnets to 1.9 degrees above absolute zero, colder than deep space at 2.7, because helium turns superfluid down there and becomes a far better coolant.

Why does Earth's air hold barely any helium, the universe's second most common element?

It escapes into space: helium is so light that Earth's gravity cannot hold on to it, so every balloonful released is gone for good.

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

Radioactive decay of uranium and thorium fires out alpha particles, and each one grabs two electrons from the surrounding rock to become a helium atom.

From what source is commercial helium extracted?

Natural gas from a new Kansas well refused to catch fire in 1903, and chemists later found helium in it; gas fields have supplied the world ever since.

Google's Project Loon floated helium balloons in the stratosphere to beam down what?

Internet access: the balloons drifted on the wind, and Loon steered each one by raising or lowering it into a layer blowing the right way.

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

Amarillo, Texas, sits beside a natural underground rock dome that could hold the gas, which the government first stockpiled to fill military airships.

Why did the Hindenburg fly on flammable hydrogen rather than helium?

A US law banned helium exports and America was the only producer, so the Hindenburg, designed for helium, had to be filled with hydrogen.

Compared with hydrogen, what is helium's drawback in an airship?

It lifts less weight than hydrogen does, yet after the airship Roma burned in 1922 American airships never flew on hydrogen again.

As of 2024, which small Gulf state supplied about a third of the world's helium?

Qatar's share is so large that when its neighbours cut off its trade routes in 2017, buyers around the world braced for helium shortages.

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

The Department of the Interior ran the reserve through its Bureau of Land Management, and the 1996 act told it to sell the stockpile to pay back what the government had spent on it.

A huge helium field was found in 2016 beneath the Rift Valley of which African country?

Tanzania's volcanoes did the work: they baked helium out of ancient rock, and it rose to collect in shallower traps where geologists went looking.

The astronomer who named helium also founded which famous journal in 1869?

Nature first appeared in November 1869 with the amateur astronomer as its editor; by day he was a clerk in Britain's War Office.

Helium-3 has one fewer of which particle than helium-4?

Neutron: helium-3 has one where helium-4 has two, and it absorbs a stray one so readily that border detectors use it to spot smuggled nuclear material.

Solar wind has loaded which body's surface with helium-3, prompting ideas of mining it as fusion fuel?

The Moon has no magnetic field to shield it, so the solar wind has been planting helium-3 in its surface dust for billions of years.

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

A few minutes: by then the newborn universe had cooled enough for particles to fuse into helium, and soon after it grew too thin for fusion to go on, fixing the mix seen today.

Astronomers think helium hydride, made as the early universe cooled, was the very first what?

Molecule: a helium atom bonded with a bare proton long before any star existed, and in 2019 astronomers finally detected the ion in a distant nebula.

Welders pay extra for helium's hotter arc when joining which pair of fast-cooling metals?

Aluminium and copper are such good conductors that a weld pool struggles to stay molten, and helium's hotter arc makes up the difference.

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

Nitrogen narcosis is a drunken fog that nitrogen brings on under pressure; helium has almost no narcotic effect, so deep divers swap it in.

Helium-neon lasers usually produce a beam of what colour?

Red: the helium atoms only soak up energy and pass it to the neon, which gives off the light, and for years that beam read the barcodes at supermarket checkouts.

Rockets such as the Saturn V carry helium mainly to do what?

Pressurise the fuel tanks: as the engines drain them, helium fills the gap, because it stays a gas even beside super-cold propellants.

In 2012, which daredevil rode a helium balloon 24 miles up and jumped, breaking the sound barrier?

Felix Baumgartner had Joseph Kittinger in his ear: the man whose 1960 record he was breaking served as his radio link in mission control.

Which industrial job relies on helium because its atoms are so small?

Leak detection: engineers fill a sealed part with helium, and a detector outside picks up any atoms that escape, pinpointing even tiny flaws.

Why are some high-capacity computer hard drives sealed with helium inside instead of air?

The disks spin with less drag in thin helium, so the drive sips less power and makers can pack in more platters; the first went on sale in 2013.

What does a helium-oxygen mix do for patients with narrowed airways?

Flows more easily: heliox is far less dense than air, so it slips through a tight airway with less effort.

In 1982, Larry Walters rose 16,000 feet over Los Angeles beneath 42 helium weather balloons, sitting in what?

A lawn chair: startled airline pilots reported him to the control tower, and he came down by popping balloons one by one with an air gun.

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

It is normally used only for metals, as in sodium and lithium; helium kept its metallic-sounding name even after it turned out to be a gas.

In World War II, helium-filled US Navy blimps escorted convoys mainly to hunt for what?

Enemy submarines: the Navy's patrol blimps watched over thousands of ships, lowering listening devices into the water to find the subs.

The US Navy's giant helium airships Akron and Macon served in the 1930s as flying what?

Aircraft carriers: each carried small fighter planes in its belly and could launch them and hook them back aboard while cruising through the sky.

Why does helium almost never react with other elements?

Its outer electron shell is full: with nothing to gain by sharing or swapping electrons, a helium atom has no reason to bond with anything.