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The group 18 elements involve helium, argon, krypton, neon, xenon, and radon. In the outermost orbit, the members of the group possess eight electrons. However, helium has only two electrons. Group 18 elements are chemically unreactive and are gases that do not form compounds. They are located at the extreme right of the periodic table and are commonly known as inert gases or noble gases due to their unreactive nature.
Group 18 Elements: Electronic Configuration
The universal configuration of valence shells is given as ns2np6, with helium as the exception which has the configuration of 1s2.
Group 18 Elements Occurrence
- Except for radon, all of the elements are present in a free state in the atmosphere.
- Out of the total atmosphere, 1% is made up of these gases and argon alone accounts for 0.93%.
- Helium, neon and argon can be found as disintegrated gases in some water springs.
- Radon can be obtained by the decay of thorium minerals and radium.
- Natural gas deposits are one of the essential and commercial sources of helium.
Group 18 Elements: Characteristics
Let us now know about the characteristics of group 18 elements.
- They show a stable octet configuration and consist of eight valence electrons in the outermost orbit except for helium, which has a duplet configuration.
- The atomic radii present in the group 18 elements are very small. As the noble gases increase down the group, the atomic radii increase along with an increase in atomic number.
- Members of group 18 elements show large positive values of electron gain enthalpy.
- All the members of group 18 elements, except helium have eight electrons in their outermost shell and exhibit duplet configuration. Thus, they possess a high ionisation enthalpy.
- Due to the increase in the atomic size of group 18 elements as we move down the group, the ionisation enthalpy decreases.
Group 18 Elements: Physical Properties
The physical properties which the group 18 elements exhibit are mentioned below.
- These elements exist in a free state due to their stable nature.
- These gases are colourless, tasteless and odourless.
- They are sparsely dissolvable in water.
- Due to the weak Vander Waals force, these gases can be condensed at very low temperatures.
- Of all the group 18 elements, Helium has the least boiling point.
Group 18 Elements: Chemical Properties
Understanding the chemical properties of the members of group 18:
- Due to their stable electronic configuration, they are chemically latent.
- On moving down the group ionisation enthalpy decreases and it increases the chemical movement of the group 18 elements.
- The elements consist of high ionisation enthalpy and high positive electron gain enthalpy.
- Neon, helium and argon have a high ionisation enthalpy and this prevents them from forming compounds.
- Radon shapes a few compounds like radon difluoride because it has less ionisation enthalpy.
- Krypton forms krypton difluoride only due to its higher ionisation enthalpy than xenon.
Uses Of Helium
- Since Helium is flammable and has a low density, it is used in filling weather balloons and aircraft because and is also useful in cooling down the superconducting magnets.
- It is used as a cryogenic agent to conduct low-temperature tests due to its minimal boiling point.
- To get the low temperatures for superconductivity liquid, helium is used.
- Helium can also be used as stream and cooling gas, in gas-fluid chromatography and gas-cooled atomic reactors.
- Helium is also used in oxygen cylinders, particularly which are used in sea diving activity.
Uses of Radon, Argon, Krypton, Xenon, And Neon
- Neon finds its utility in release tubes where it is used in minute amounts and bright lighting bulbs which are used as neon signs.
- Argon is widely used for various metallurgical activities like welding magnesium, aluminium and stainless steel. It is also used to maintain a stable atmosphere in mechanically assembled research centres.
- Radon is used in radiotherapy for the treatment of cancer.
- Xenon is widely used as a part of release tubes which serves the rapid flash necessary for photography.
- Krypton is used for fibre lights and release tubes.
Conclusion
Group 18 elements consist of gases that are chemically unreactive and do not form compounds. These gases are helium, argon, krypton, neon, xenon, and radon. These elements have eight electrons in their outermost orbit. However, helium is an exception with two electrons. They are located at the extreme right of the periodic table and are commonly known as inert gases or noble gases due to their unreactive nature.
All of the elements are present in a free state in the atmosphere except Radon. Some gases like Helium, neon and argon can be found as disintegrated gases in some water springs. There are several physical and chemical properties of these elements. Helium has the lowest boiling point.
These gases have several uses like helium is used in filling weather balloons and aircraft and it is used as a cryogenic agent to conduct low-temperature tests. Krypton is used for fibre lights and release tubes and Radon is used in radiotherapy for the treatment of cancer.
