Why Is Helium a Noble Gas? (+ 3 Things to Know)

Helium is a noble gas because it has a completely filled outermost electron shell, which makes it highly stable and non-reactive. In other words, it has a full valence shell with two electrons, which gives it a very low tendency to form chemical bonds with other atoms. ¹

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Explanation: Why is helium a noble gas?

Helium is a noble gas because its outermost electron shell is completely filled with two electrons, which makes it very stable and non-reactive. 

Atoms of elements tend to gain, lose, or share electrons to fill their outermost electron shell and achieve stability. 

Helium already has a full outermost electron shell, so it doesn’t need to form chemical bonds with other atoms to achieve stability. This makes helium a very unreactive or inert gas.

In other words, the electrons in helium are arranged in such a way that the atom is happy with its configuration and doesn’t need to share or exchange electrons with other atoms to become more stable. 

This makes helium very unlikely to combine with other elements to form compounds, which is why it is considered a noble gas.

In summary, helium is a noble gas and non-reactive because its electron configuration is highly stable, meaning it does not need to form chemical bonds with other atoms to become more stable.

Stability of helium compared to other noble gases

Helium is the first element in the noble gas group of the periodic table, and it is known to be the most stable of all the noble gases. ² This is because it has the smallest atomic size and the lowest electron affinity among the noble gases, which makes it highly inert and non-reactive.

The other noble gases, such as neon, argon, krypton, xenon, and radon, also have stable electron configurations due to having full outermost electron shells. ^{3 4}

However, as we move down the group from helium to radon, the atomic size increases, and the electron affinity becomes more negative. ⁵

This means that the outer electrons are farther away from the nucleus and are more easily attracted to other atoms, making the noble gases more reactive.

Despite being the most stable of the noble gases, helium is not completely inert, and it can form some weak interactions with other atoms or molecules under certain conditions. ^{6 7 8}

For example, it has been found that helium can form weak van der Waals forces with other atoms or molecules, which are attractive forces that arise due to fluctuations in electron density.

Overall, helium is the most stable of the noble gases due to its small atomic size and low electron affinity, which make it highly inert and non-reactive. 

However, it is not completely inert and can form weak interactions with other atoms or molecules.

Uses of helium due to its inert nature

Helium’s inert and non-reactive nature makes it useful in a wide range of industrial and scientific applications. Some common uses of helium include:

1. As a coolant: Helium’s low boiling point and high thermal conductivity make it an ideal coolant for various industrial applications, such as in nuclear reactors and MRI machines.
2. In welding: Helium is often used in welding processes as it provides an inert atmosphere that prevents the formation of oxides and nitrides that can weaken the weld. ⁹
3. In leak detection: Helium is a small molecule that can easily penetrate small leaks, making it useful in detecting leaks in various systems such as refrigeration, air conditioning, and gas pipelines. ¹⁰
4. In gas chromatography: Helium’s low atomic weight and inertness make it an ideal carrier gas for gas chromatography, a technique used in analytical chemistry to separate and analyze complex mixtures of chemicals.
5. In balloons: Helium’s low density and non-toxic nature make it ideal for filling balloons, blimps, and other lighter-than-air vehicles. ¹¹
6. In scuba diving: Helium is sometimes used as a component in breathing mixtures for deep-sea diving, as it reduces the risk of nitrogen narcosis and decompression sickness. ¹²
7. In space exploration: Helium is used as a coolant in space telescopes and other instruments that operate at extremely low temperatures.

Overall, helium’s inert and non-reactive nature makes it a valuable resource in a variety of important applications.

Further reading

Is Helium a Metal?
Is Helium Diatomic?
Is Lithium a Metal or Nonmetal?
Why is Boron a Metalloid?
Is Hydrogen a Noble Gas?

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