The Noble Gases

Podcast Transcript

Located on the far right side of the periodic table are the Noble Gases. These elements, six of which can be found in nature, are unlike any other elements.

They don’t play well with the other elements and are pretty content to be by themselves.

Nonetheless, they have found a unique place in technical products, industrial applications, and even space flight.

Learn more about Noble Gases, aka the inert gases, on this episode of Everything Everywhere Daily.

In the past, I’ve done episodes on individual elements. I could probably do an episode on helium, but once you get beyond that it would be hard to do a full episode on the individual noble gases, so I figured I’d just lump them all together.

Before I get into talking about the individual elements I should probably briefly explain what makes the inert gases…..inert.

Each column on the period table is called a group, and what each group has in common is a valence number. A valence number describes the number of electrons that are in the outermost electron shell of an element.

For example, the alkali metals such as sodium, potassium, and lithium all have one electron in their valence shell. The halide group includes fluorine, chlorine, and iodine.

Every atom wants to have a complete outer valence shell. Alkali metals want to give up an electron and halide elements want to take an electron to fill their shell.

Molecules are created by elements sharing electrons, and how they combine will depend on their valence electrons.

In the case of noble gases, they have a full set of electrons in their valence shell. They have no desire to give or take electrons. They are good just as they are.

This full valence shell is why inert gases are inert. It is very difficult for them to bind with anything and there are almost never molecules or compounds found in nature with these elements.

As a result, all of these elements are colorless, odorless, monoatomic gases.

There are six naturally occurring noble gases: helium, neon, argon, krypton, xenon, and radon.

The first and lightest of the noble gases is Helium.

I’ve talked about helium before in several episodes. It is the second most abundant element in the universe after hydrogen. It has an atomic number of 2, which means that it is extremely light. Any helium which is released into the atmosphere will be permanently lost.

If you let the gas out of a helium balloon, that gas will eventually rise to the very top of the atmosphere and go into space, and it will probably be caught in the solar wind.

Helium was created in the early universe and it is also created inside of stars. However, almost all of the helium found on Earth comes from radioactive decay, in particular alpha decay.

If you remember back to my episode on radiation, alpha decay is when a radioactive element expells a helium nuclei out of its nucleus.

Deep within the Earth, there is a large amount of radioactive decay. This decay is actually responsible for most of the heat inside the core and mantle of the Earth.

The helium which is created will gradually make its way up, closer to the surface.

Helium was discovered in 1868 in the sun before it was found on Earth.

Most Helium on Earth comes from drilling for oil and gas. As it rises up, pockets will get stuck in anticlines where oil and gas is often present. In 1903 in Kansas, when drilling for oil, the drillers hit a gas pocket that oddly wouldn’t burn.

Despite being one of the most common elements in the universe, helium is rather rare on Earth.

You are probably familiar with helium and its use in balloons and blimps. It is great for lifting, and it doesn’t explode as hydrogen does.

However, there are many other industrial applications for helium. It is used in certain welding applications as well as in the creation of crystals. Liquid helium is also used to cool the powerful magnets in Magnetic Resonance Imaging machines.

One potentially huge future use of helium would be in nuclear fusion. One isotope of helium, in particular, Helium-3 has great potential for fusion. The problem is, that helium-3 is even rarer than regular helium-4. It is usually created when a helium nucleus is hit by a cosmic ray.

One possible location where there might be a large amount of helium-3 is the moon. The development of fusion energy might just encourage more exploration of the moon.

There is currently a shortage of helium in the world. This has resulted in several physics laboratories canceling projects because they can’t get enough helium. Today, as I am writing this episode, Harvard announced the cancellation of experiments due to a lack of helium.

Something to think about the next time you get helium balloons.

The next noble gas is another one that you are probably familiar with: Neon.

Neon has an atomic number of 10, and I’m sure everyone is familiar with neon lights.

Neon was discovered in 1898 after liquifying atmospheric air and figuring out what was left after the major elements were taken out. Neon is the 5th most common component of atmospheric air making up 0.0018% of air.

Neon being heavier than helium, doesn’t escape to space when exposed to the atmosphere. The neon found on Earth is a combination of both primordial neon and neon from radioactive decay.

65% of the neon in the world comes from a single company: Iceblick. Iceblick operates in Ukraine and in Russia, and as you can guess, this has resulted in a global shortage of neon since the start of the Russo-Ukrainian conflict. The price of neon jumped over 600% after the start of the conflict.

They get neon by separating it from air. In fact, all of the noble gases other than helium are mostly acquired via a process known as cryogenic air separation. You liquefy air by cooling it down. The primary products are liquid oxygen and nitrogen, but you also get trace amounts of other gases in the atmosphere.

The biggest use for neon, as you might guess, is for neon lights. When an electrical current is applied to neon, it will glow a bright red-orange. If you see neon signs in other colors, it is usually due to coloring in the glass tube that contains it.

Beyond that, there are some limited uses in lasers, computer chip production, and in vacuum tubes.

In any application where you just want a gas that won’t react, other gasses are a much cheaper alternative, such as the next nobel gas: Argon

Argon has an atomic number of 18 and it is actually the third most common element in air, making up almost 1% of the air you are breathing right now.

Argon is, on average, more abundant than water vapor and carbon dioxide in the air. The fact that it is so abundant means that it is much cheaper than neon or helium.

If you need something very inert, argon is usually going to be the best choice due to cost. Carbon dioxide is often used as a fire suppressant, but in some high-tech applications, argon is used to put out fires because it is guaranteed not to react to anything else.

Argon is a common gas used in welding, some aerosol cans, and as a preservative. The original United States Constitution and Declaration of Independence are encased in argon-filled containers.

The next noble gas is krypton. Krypton has an atomic number of 36, and it is about 100x rarer than Argon.

Krypton consists of about 1 part per million of the air in the atmosphere you breathe. You can get it from cryogenic air separation like all the other gases, but not very much, which is why it is so expensive.

There aren’t a lot of uses for krypton because in most cases you could use it you would use cheaper argon instead. However, there are some very specific technical cases where krypton is more suitable, including as a coolant in high-end physics projects.

Small amounts are also used in some fluorescent lights and sometimes as an insulating agent between panes of glass.

Xenon is the fifth noble gas with an atomic number of 54. It is 11.5 times rarer than krypton in the atmosphere.

Xenon is the first noble gas that is above iron on the period table, which, if you remember back to the episode on how stars work, means it is not produced in stars via normal stellar evolution.

It is produced like heavier elements in a supernova, and as a by-product of radioactive decay.

Xenon created by radioactive decay is actually a really big problem in nuclear reactors. Xenon-135, which only has a half-life of 9.2 hours, is what is known as a neutron poison. In fact, it is the biggest known neutron poison in existence.

Neutron poisons can really impede nuclear reactors. Xenon poisoning actually contributed to the Chornobyl nuclear disaster, and it is something that nuclear engineers have to consider whenever designing a reactor.

Xenon also played a role in space travel.

Some satellites use what is known as an ionic thruster. It simply uses electricity to expel gases that have been given an electrical charge. Xenon is a preferred fuel source for ionic thrusters because it is such a heavy gas, which means each atom expelled provides more force.

While xenon is a great fuel source it is also really expensive, so many satellites have shifted to iodine.

The final and heaviest noble gas is radon.

Radon is the only noble gas that is radioactive. It has an atomic number of 86 and it was discovered by Nobel prize winner Marie Curie. It is a product of the natural decay of uranium and thorium via the element radium.

There are very few applications for radon. What little radon that is collected for industrial use is incredibly expensive. It is collected via uranium mining and it can sell for thousands of dollars per milliliter.

It has some very limited medical uses, but most scientists can use it as a natural radiation marker in soil or groundwater.

The biggest issue with radon is that it is a serious health threat. Because it is naturally occurring, radioactive, and it is the heaviest gas, it can accumulate in places like basements and mines. Radon will settle in low-lying places because it is so heavy.

As it is an alpha-emitting gas, it is the second-largest cause of lung cancer after smoking.

Thankfully, radon is easy to detect and if there is a build-up of radon it is easy to fix with proper ventilation.

I should note that there is a seventh theoretical noble gas. It would be element 118 on the periodic table and it has been given the name Oganesson. It doesn’t exist in nature and it has only existed in a laboratory for a few fractions of a second.

It was named after Yuri Oganessian who helped discover many of the heavy elements created in laboratories.

The noble gases are very different than any other group of elements. They don’t react with anything and they have very limited use.

Yet you’ve unknowingly been breathing them your entire life without even knowing it, unless you sucked helium out of a balloon, in which case, you definitely knew it.

Everything Everywhere Daily is an Airwave Media Podcast.

The executive producer is Darcy Adams.

The associate producers are Thor Thomsen and Peter Bennett.

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