
Natural Sources Abundance and Isolation of Noble Gases in Nature
As a kid, we all love to buy balloons that float in the air, seeing the balloon floating in the air without any fans and engines always makes us feel like its a magic. Well, indeed its a magic but, its a magic of science. We still personally know how it feels when the balloon you just bought flys away as you were lost in eating ice-cream in the fair.
That feeling is terrible, so to save your balloon we tell you a little trick, always tie the thread of your ballon with your one hand, the one you don’t use, don’t tie it on your fingers, tie it on one of your arms and have a great time. Well, nostalgia’s apart let us discuss what indeed makes a balloon fly away on its own. Today we are going to talk about group 18 elements, there occurrence in nature, properties, and some interesting facts to amaze you.
Group 18 Periodic Table
The group 18 elements are called noble gases, and all of the 18 group elements are colorless, odorless, tasteless, and non-flammable gases under normal conditions and room temperature.
The elements of group 18 are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Re).
All of these elements from group 18 of the periodic table occur naturally on earth. Any given element is said to be noble gas if it doesn’t react with other chemicals and is inert to them. It has been discovered that elements from group 18 cannot form bonds with other atoms and thus are not able to form any compound. But later as the technology gets better and scientists were able to find the electronic structure it was found even noble gases can form some compounds.
Also, when they were first discovered, scientists said these elements are quite rare. Now in the 21st century, we know they are well abundant elements on earth and in-universe, so saying them as a rare element is an entirely false statement.
When we are referring something as noble in terms of chemistry, it means that the following element will show reluctance to metals. Some of these elements are gold and platinum. The same property is applicable for elements from 18 groups of the periodic table.
Why Are Elements of Group 18 Inert In Nature?
Group 18 elements are called inert due to their atomic structure which gives them little tendency to perform any chemical reactions. The outer shell of these elements is considered to be full, leaving no space for the share or transfer of electrons from another element.
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The atomicity of noble gases is one meaning each individual molecule has one element of a given noble gas. In normal conditions, these gases are present in monoatomic. As a result, the atomicity is 1. Helium is one of the best examples that shows theses nobles gases have one atomicity. All the elements present in group 18 either have duplets or octets in their valance shell. As a result, they don’t have any inclination to form compounds by reacting with other elements. It shows inert behavior to other chemicals.
Furthermore, their valency is zero, so they don’t take any electron, and neither do they impart any electron from their valance shell. As a result, they are inert.
Properties of Elements From 18 Group
You would be shocked to know some of these facts and properties but the one gas that gives a ballon ability to fly without any engine is the most abundant rare gas in the atmosphere. Yes, helium is 0.000052% of the total air present in our earth’s atmosphere. Just like that, we have written down some important properties for group 18 elements.
On the other hand, if speaking about the earth as a whole the most abundant noble gas is Argon due to its stable nucleus giving the element inert properties.
The nuclear radius gets an increment as we move down the group 18 due as we witness the increase in nuclear number. As we move from top to the bottom of the group, each progressive element will have show the expansion by adding up new shells.
The elements have high ionization potential due to their closed electronic configuration.
In addition to this, the particles hold each other with weak Vander Walls Force. As we go down and the new shells get added to each element, the extent of these forces increases along with the polarizability of molecules.
Due to weak Vander Wall forces, these elements have lower boiling and melting points.
As we go down the liquefaction of these gases becomes easier as the new shell is added after each element, leading to an increase in the Vander wall forces.
FAQs on Occurrence of Group 18 Elements in the Earths Atmosphere and Crust
1. What is the occurrence of Group 18 elements in nature?
The Group 18 elements (noble gases) occur mainly in the atmosphere in free, monoatomic form due to their chemical inertness.
- Helium (He) is found in natural gas deposits and in traces in air.
- Neon (Ne), Argon (Ar), Krypton (Kr), and Xenon (Xe) are present in the atmosphere in small amounts.
- Radon (Rn) occurs in trace amounts as a radioactive product of uranium and thorium decay in rocks.
2. Why are noble gases found in free state in nature?
Noble gases are found in the free (uncombined) state because they have a complete valence shell, making them chemically inert.
- They have stable electronic configurations: ns2 np6 (except helium: 1s2).
- This stable configuration gives them zero or very low reactivity.
- They do not readily gain, lose, or share electrons.
3. What is the abundance of noble gases in the atmosphere?
Among noble gases, argon is the most abundant in the atmosphere, making up about 0.93% by volume of air.
- Helium: ~5.2 ppm
- Neon: ~18 ppm
- Argon: ~0.93%
- Krypton: ~1 ppm
- Xenon: ~0.09 ppm
4. How is helium obtained in nature?
Helium is obtained mainly from natural gas deposits where it accumulates due to radioactive decay of heavy elements.
- It is formed by alpha decay of uranium and thorium nuclei.
- The emitted alpha particles (4He2+) capture electrons to form helium atoms.
- Helium is extracted commercially from natural gas by fractional distillation.
5. Where is radon found in nature?
Radon is found in trace amounts in the atmosphere as a product of radioactive decay of radium in rocks and soil.
- Radon (Rn) is formed in the decay series of uranium-238.
- It is a radioactive noble gas.
- It can accumulate in poorly ventilated buildings and underground mines.
6. Why is helium less abundant in the atmosphere compared to argon?
Helium is less abundant in the atmosphere because its low atomic mass allows it to escape Earth’s gravitational field.
- Helium atoms are very light and move at high speeds.
- Over time, they escape into outer space.
- Argon, being heavier, remains trapped in the atmosphere.
7. How are noble gases separated from air?
Noble gases are separated from air by fractional distillation of liquid air.
- Air is first liquefied by cooling and compression.
- Components are separated based on their different boiling points.
- Argon, neon, krypton, and xenon are obtained during this process.
8. In what form do Group 18 elements exist in nature?
Group 18 elements exist as monoatomic gases in nature.
- They do not form molecules like O2 or N2.
- Each atom is independent due to complete valence shell stability.
- They show very weak intermolecular forces.
9. Why is argon the most abundant noble gas in air?
Argon is the most abundant noble gas in air because it is formed continuously by the radioactive decay of potassium-40 in Earth’s crust.
- 40K decays to 40Ar.
- Argon is heavy enough to remain in the atmosphere.
- It does not react chemically and therefore accumulates over time.
10. Are noble gases found in minerals or only in air?
Noble gases are found both in the atmosphere and in certain minerals and natural gas deposits.
- Helium is present in natural gas fields.
- Radon is found in uranium- and radium-containing minerals.
- Other noble gases are mainly atmospheric.





















