Science, Maths & Technology
  • Video
  • 5 mins
  • Level 1: Introductory

Noble gases

Updated Tuesday 17th July 2007

Noble gases. Some balloons. A rooftop. Watch what happens...


Copyright The Open University

Text version

Here are five of the six noble gases: helium, neon, argon, kypton and xeon. They're all colourless and transparent. Krypton and xeon form compounds only with difficulty. Helium, neon and argon don't form compounds at all.

As we descend the group in the periodic table the atomic number and relative atomic mass increases. The gasses get denser.

Helium - helium is lighter than air. Neon is just lighter. Argon and krypton - I've just got to unstick these from the anchorage... Argon and krypton are both heavier than air. And xeon, xeon is the heaviest of the lot, you've heard of a lead balloon, well this is it.

The science

The noble gases, in order of their density, are helium, neon, argon, krypton, xenon and radon. They are called noble gases because they are so majestic that, in general, they don’t react with anything. For this reason they are also known as inert gases.

The noble gases are present in the atmosphere in small amounts:

  • 0.934% Argon
  • 0.0018% Neon
  • 0.00052% Helium
  • 0.00011% Krypton
  • 0.000009% Xenon

Most of the noble gases are extracted from the air, except for helium. Helium is a product of radioactive decay (the alpha particle) and is found naturally in rocks. Most of the helium used nowadays comes from natural gas, of which it comprises 7%.

Helium, the lightest, is used for filling party balloons. It is also mixed with oxygen to create a mixture that divers can breathe at depth – the helium is not very soluble in the blood so it avoids the “bends”.

Neon is probably most famous for neon signs – a tube containing neon gas through which a current is passed which causes the gas to give out light. When mixed with helium it is used to make helium-neon lasers.

Argon is used as the inert atmosphere in many light bulbs – an electric current is passed through a wire to heat it up so that it gets so hot it emits light. At these temperatures the metal would react with any oxygen present which is why an inert gas is needed.

Krypton is used to produce white light for photography – again an electrical current is passed through the gas so it emits light.

Xenon is again used in high quality lamps such as those used in lighthouses and in lasers.

Radon is a radioactive element. Radon gas is formed by decay of other radioactive elements and the concentration in the environment depends upon the types of rocks on which you live. For example, the granite in Dartmoor contains small amounts of uranium that forms radon, which can accumulate in buildings and drinking water. This leads to an increased risk of cancer.


For further information, take a look at our frequently asked questions which may give you the support you need.

Have a question?

Other content you may like

Elements of the Periodic Table Creative commons image Icon The Open University under Creative Commons BY-NC-SA 4.0 license activity icon

Science, Maths & Technology 

Elements of the Periodic Table

Explore the impact of chemical elements on our bodies, our world, and see how they changed the course of history

Carbon process: Upwelling Copyrighted image Icon Copyright: article icon

Science, Maths & Technology 

Carbon process: Upwelling

The turbulence of water in the oceans can send carbon on a journey.

Fruits of the vine Copyrighted image Icon Copyright: Yurok Aleksandrovich via audio icon

Science, Maths & Technology 

Fruits of the vine

An investigation into the chemistry of wine making from The New Curiosity Shop.

20 mins
Ever Wondered About... Food additives? Copyrighted image Icon Copyright: Production team article icon

Science, Maths & Technology 

Ever Wondered About... Food additives?

Are the additives in foods giving us more than just a longer shelf life and distinctive flavour?

Make a waterproof tent Copyrighted image Icon Copyright: Production team article icon

Science, Maths & Technology 

Make a waterproof tent

How would you set about waterproofing a tent if you only had what was to hand, your wits, and science to help?

Putting the elements in order Copyrighted image Icon Copyright: The Open University video icon

Science, Maths & Technology 

Putting the elements in order

See how patterns and trends between the chemical elements helped to shape the Periodic Table

5 mins
Birth of a drug Copyrighted image Icon Copyright: Used with permission free course icon Level 3 icon

Science, Maths & Technology 

Birth of a drug

The search for new medicinal products is one of the major driving forces behind the development and application of new synthetic methods. This free course, Birth of a drug, focuses on a specific case study that follows the development of a drug for the treatment of high blood pressure. It is a particularly good example of the application of organic chemistry in the pharmaceutical industry, and illustrates the scientific processes that are involved in the development of any new drug.

Free course
4 hrs
Mike Bullivant's diary: Underwater torch Copyrighted image Icon Copyright: Production team article icon

Science, Maths & Technology 

Mike Bullivant's diary: Underwater torch

Mike Bullivant's Sun and Sea diary, from the BBC/OU series Rough Science 2

Mosquitoes & Malaria Copyrighted image Icon Copyright: Production team article icon

Science, Maths & Technology 

Mosquitoes & Malaria

In the Rough Science programme Call of the Wild, Rough Scientist Ellen has to develop a mosquito repellent