50 Fun Facts About Noble Gases

Helium was first spotted in the light of which celestial body, decades before anyone found it on Earth?

The Sun gave helium away as an unknown yellow line in its spectrum, recorded during an 1868 eclipse. The element is named after helios, the Greek word for the Sun, and was not isolated on Earth until 1895.

Why does a person's voice turn squeaky after inhaling helium from a party balloon?

Sound travels faster in it, nearly three times as fast as in air, so the vocal tract resonates at higher frequencies. The vocal cords themselves vibrate exactly as they did before.

The noble gas krypton shares its name with the doomed home planet of which comic-book superhero?

Superman was sent to Earth from Krypton, a world his creators Jerry Siegel and Joe Shuster named after the chemical element. Real krypton is a colourless gas, nothing like green kryptonite.

Signs of every colour get called neon signs, but pure neon gas itself glows which colour?

Reddish-orange is the only colour a tube of pure neon glows when electricity passes through it. Other shades come from different gases or from glowing coatings on the inside of the glass tube.

Radon seeping into homes is rated the top cause of which disease among Americans who have never smoked?

Lung cancer linked to radon kills about 21,000 Americans a year by official estimates, and only cigarettes cause more cases. The gas has no colour or smell, so only a test reveals it.

Radon seeps out of the ground and into houses, where it tends to build up in which part?

The basement sits closest to the soil, and radon is denser than air, so the gas pools there. Better ventilation or a sump under the floor usually brings the level down.

The airship Hindenburg, destroyed by fire in 1937, was lifted not by helium but by which flammable gas?

Hydrogen filled the Hindenburg because the United States, which then had a monopoly on helium, had banned its export. Airships today fly on helium, which cannot burn.

Most of the helium in the universe was forged within a few minutes of which event?

The Big Bang produced the vast majority of the universe's helium in its first few minutes, before the expanding cosmos cooled too far for fusion. Stars have been adding a little more ever since.

Xenon is the starter gas in the high-intensity lamps fitted to which part of many cars?

Headlights of the high-intensity discharge type use xenon as their starter gas. The same element fires camera flashes, and xenon lamps took over from carbon arcs in cinema projectors.

Liquid helium's main commercial job is chilling the superconducting magnets in which hospital machines?

MRI scanners rely on magnets that lose all electrical resistance only when bathed in liquid helium, a few degrees above absolute zero. Cooling of this kind is the largest use of the gas.

The noble gases fill which numbered column, on the far right-hand edge of the periodic table?

Group 18 has been the official label since 1988. Older tables called the same column group 0, because its elements were thought to have no ability to combine with anything else.

Every noble gas except helium has how many electrons in its outermost shell, a famously stable arrangement?

Eight outer electrons make a full shell, leaving the atoms with almost no reason to react. Helium is the exception with just two electrons in total, yet its one shell is full as well.

Argon's name comes from a Greek word with which meaning, a dig at its refusal to react with anything?

Lazy, or inactive, is what the Greek argos means. The gas earned the label when it was first isolated in 1894 at University College London, by stripping everything else out of a sample of clean air.

Krypton, which makes up roughly one millionth of the atmosphere, has a Greek name with which meaning?

Hidden is the sense of the Greek kryptos. The gas stayed undiscovered until 1898, when it turned up in the residue left after nearly all of a sample of liquid air had been boiled away.

Xenon's name shares a Greek root with the word xenophobia; what does that root mean?

Stranger, foreigner or guest are all senses of the Greek xenos. The name suited a gas so scarce that it makes up only about one part in 11.5 million of the atmosphere.

Which relative of neon's co-discoverer suggested naming the gas after the Latin word for new?

His son proposed novum, Latin for new. The chemist liked the idea but swapped in the Greek equivalent, which gave the world the word neon in 1898.

Which Scottish chemist won the 1904 Nobel Prize in Chemistry for discovering the noble gases in air?

William Ramsay isolated argon, helium, neon, krypton and xenon within a few years. His finds added a whole new section to the periodic table.

Which physicist's discovery that nitrogen from air outweighed lab-made nitrogen led straight to argon?

Lord Rayleigh traced the density gap to an unknown gas mixed into the nitrogen taken from air. He received the 1904 Nobel Prize in Physics for the work.

In 1962 Neil Bartlett made the first noble gas compound by bonding xenon to platinum and which other element?

Fluorine and platinum made up the fierce oxidising agent that Bartlett let loose on xenon. The yellow product that formed overturned the textbook rule that noble gases never react.

Radon forms naturally in rocks and soil as part of the slow decay chain of which heavy metal?

Uranium in rocks such as granite decays step by step through radium into radon, which is why the gas rises from the ground all over the world. Radon atoms themselves last only days.

Oganesson honours Yuri Oganessian; which other element was named after a scientist who was still alive?

Seaborgium was named for Glenn Seaborg in his lifetime, an honour no one else shared until oganesson was named in 2016. Einstein and Fermi both died before their elements' names became official.

Calculations suggest oganesson, the heaviest of the noble gas family, would be what at room temperature?

A solid is what theory predicts, because the pull of 118 protons warps the way its electrons behave. Only a few atoms have ever been made, each surviving about a thousandth of a second.

Xenon is the favoured propellant for which kind of spacecraft engine, used by NASA's Dawn probe to reach Ceres?

Ion thruster engines give xenon atoms an electric charge and fire them out at enormous speed. Xenon suits the job because it ionises easily and can be stored compactly as a liquid.

Despite barely reacting with anything, xenon has been used in operating theatres since 1951 as what?

A general anaesthetic is one of xenon's odder talents, first given to two patients by the American doctor Stuart Cullen. Its scarcity makes it far costlier than the usual drugs.

From 1960 to 1983, a wavelength of light given off by krypton atoms defined which unit of measurement?

The metre was fixed at 1,650,763.73 wavelengths of krypton-86 light, replacing a metal bar kept in France. Since 1983 the unit has been tied to the speed of light instead.

In which trade is argon blown over hot molten metal to shield it from the oxygen in air?

Welding is the main industrial job for argon, which will not react even with white-hot metal. Left unshielded, the molten pool soaks up gases from the air and the finished joint turns porous and brittle.

Argon is often sealed inside which household fixture because it lets less heat escape than ordinary air?

Double-glazed windows are often filled with argon, which conducts only about 67% as much heat as air. Krypton insulates better still, but it is far scarcer and costs much more.

Argon makes up nearly 1% of dry air, which puts it where among the atmosphere's most abundant gases?

Third place goes to argon, behind only nitrogen and oxygen. Air holds more than twenty times as much argon as carbon dioxide, and over 500 times as much argon as neon.

Nearly all the argon in Earth's atmosphere was made by the slow radioactive decay of which element in rocks?

Potassium in the crust includes a radioactive form that slowly turns into argon. Geologists use that steady conversion as a clock, measuring the trapped argon to work out the age of a rock.

Chilled to about two degrees above absolute zero, liquid helium becomes which friction-free state of matter?

Superfluid helium flows with no measurable viscosity, slipping through channels far too narrow for an ordinary liquid. Pyotr Kapitsa in Moscow and two physicists in Cambridge independently reported the effect in 1938.

The US National Helium Reserve, created in 1925, kept its gas in an underground rock dome in which state?

Texas was chosen for the reserve, set up to keep military airships supplied and later a provider of coolant during the Cold War. The helium was held in a rock dome about 12 miles from Amarillo.

Helium counts as a non-renewable resource on Earth because, once released, it promptly does what?

Escapes into space is the fate of any helium let loose, so every balloon's worth is gone for good. That is why air holds only about five parts per million of the universe's second commonest element.

Before cheap diodes took over, a helium–neon laser beam did which everyday job in supermarkets?

Reading barcodes at the checkout was long the most familiar job of the helium–neon laser. It was also the first laser of any kind to produce a continuous beam instead of pulses.

Helium is blended into breathing mixtures such as heliox and trimix for people doing which activity?

Deep-sea diving calls for helium because, unlike nitrogen, it has no narcotic effect under pressure. The foggy-headed feeling that nitrogen causes gets worse the deeper a diver goes.

Which English scientist, founder and first editor of the journal Nature, gave helium its name?

Norman Lockyer alone argued that a mystery yellow line in a spectrum came from an unknown element. His choice of the ending -ium, normally kept for metals, is a quirk that stuck.

Engineer Georges Claude first showed neon tube lighting to the public in 1910 at a motor show in which city?

Paris saw two giant tubes of glowing neon lit up in the Grand Palais at its Motor Show that December. Claude's patents then gave his company a near monopoly on neon signs into the early 1930s.

In so-called neon signs, a blue glow comes from the vapour of which metal, also used in fluorescent tubes?

Mercury vapour glows blue and also gives off ultraviolet light, which makes fluorescent coatings on the inside of a tube shine in many other colours.

Unlike oxygen and nitrogen, which go around in bonded pairs, the noble gases drift about as what?

Single atoms are all a noble gas needs to be, because a full outer shell leaves nothing to share with a partner. Chemists call such gases monatomic.

Almost all commercial helium is extracted as a by-product of drilling for which fuel?

Natural gas from some fields is as much as 7% helium, built up from the decay of radioactive elements in the rock. Chilling the mixture until everything else turns liquid separates the helium out.

A helium nucleus is identical to which kind of radiation thrown out by unstable heavy atoms?

Alpha particles are simply two protons and two neutrons bound tightly together. Each one eventually picks up two electrons and becomes an atom of helium gas.

Proposals to mine helium-3, a rare form of helium prized as fusion fuel, centre on which dusty body?

The Moon is thought to hold far more helium-3 than Earth, built up in its top layer of dust over billions of years. Schemes to mine it there have been put forward since 1986.

Excimer lasers, fed by mixtures containing argon, krypton or xenon, are the standard tool in which procedure?

LASIK eye surgery uses the laser's ultraviolet beam to reshape the cornea, removing microscopic amounts of tissue. The same kind of laser prints the circuits on computer chips.

A tube filled with low-pressure helium, neon or argon is the heart of which instrument, famous for its clicking?

Geiger counter tubes hold the gas at high voltage, so each ray that passes through knocks electrons loose and sets off a pulse of current. Every click marks one such event.

Helium, the second-lightest element, holds the record among all the elements for the lowest what?

Boiling point is where helium beats everything: it does not turn liquid until cooled to about −269 °C, some four degrees above absolute zero. At ordinary pressure it never freezes at all.

Which traditional household item is filled with argon to help its glowing filament last longer?

Light bulbs of the filament type were given a gas filling after Irving Langmuir found in 1913 that it doubled their efficiency and kept the glass from blackening.

The original US Declaration of Independence rests in an argon-filled case at which Washington institution?

National Archives conservators resealed the Declaration and the Constitution in argon in the early 2000s. It replaced helium, used for the previous five decades, which leaks out of a sealed case more quickly.

Physicists build detectors around tanks of liquid xenon in the hope of catching which elusive substance?

Dark matter, if some theories are right, should now and then strike a xenon nucleus and cause a faint flash. Dense liquid xenon raises the odds of a hit.

Makers of which drink float a blanket of argon over the liquid to stop oxygen from spoiling it?

Wine left open to oxygen feeds the bacteria that make acetic acid, the sour heart of vinegar. Argon is denser than air, so it settles over the surface as a barrier.

Helium was first turned into a liquid in 1908 by Heike Kamerlingh Onnes, a physicist working in which country?

The Netherlands was home to his laboratory at Leiden University, which reached the lowest temperature then recorded on Earth. The feat helped win Onnes the 1913 Nobel Prize in Physics.

Which reclusive English scientist found a stubborn bubble of unreactive air a century before argon was named?

Henry Cavendish stripped the oxygen and nitrogen from a sample of air and was left with a tiny bubble, about 1/120 of the nitrogen's volume, that would not react. It was argon, unrecognised until the 1890s.