Noble gases or inert gases are a family of the periodic table known for their high stability and unreactive nature. They have complete valence electrons and do not react with other elements of the periodic table. This is not a deficiency on their part, but a satisfaction of the octet rule.
These elements are content with their electronic configuration and would rather not react by losing or gaining electrons. But is this all there is to the reason for the unreactive nature of noble gases? Aren’t there any exceptions? This article provides answers to these questions and provides information on the applications of these elements.
An overview of the noble gases
The noble gases are a family of six elements. They are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). They are found in group 18 (VIIIA) of the periodic table, which accounts for their eight valence electrons.
These elements are known for their complete octet, stability, and unreactive nature.
Why are noble gases unreactive?
The nature of noble gases has three explanations. They are:
1. Their electronic configuration
Electron configuration is a major driving force behind chemical reactions. Chemical reactions come about from the sharing or transferring of electrons to fill valence shells.
Noble gases have a stable electronic configuration. They all have full valence shells that satisfy the octet rule. Helium has two electrons in its valence shell and the other elements have eight electrons in their valence shells.
The electrons are also arranged in energy levels or electron shells around the nucleus. This arrangement and electronic configuration explain the unreactive nature of these gases. It shows their satisfaction and unwillingness to participate in chemical reactions.
2. The octet rule
The octet rule, also known as the rule of eight, is a fundamental principle in chemistry. This rule states that atoms are most stable when they have eight electrons in their valence shell.
Noble gases follow the octet rule. Their valence shells are complete, containing the maximum number of electrons they can hold. Consequently, they do not gain, lose, or share electrons with other atoms. This is how the octet structure explains the unreactive nature of the noble gases.
3. The electronegativity
Noble gases are also unreactive because of their low electronegativity. Electronegativity measures the ability of an element to attract electrons and form a chemical bond. The full valence shell of the noble gases makes them have a low tendency to attract electrons.
Their low electronegativity makes them unlikely to participate in chemical reactions and form bonds with bond with other elements. They would rather retain their stable electronic configuration than lose electrons to form bonds.
Properties of the noble gases
- The noble gases have lower densities: usually denser than air (helium, for instance)
- They are not flammable
- Noble gases are colorless, odorless, and tasteless
- Also, they are monotonic gases with low chemical reactivity
- Noble gases have low melting and boiling points
- They are found in small amounts in the Earth’s crust and Earth’s atmosphere
- Noble gases are insoluble in water
- They are conductors of electricity and fluorescence
- Down the group, the number of occupied shells increases, and atomic radii or size increases
- Ionization potential decreases with increasing atomic size down the group
- Additionally, these elements have the highest ionization enthalpy
Xenon, the exceptional noble gas
While most noble gases are generally unreactive, there are a few exceptions under extreme conditions. For instance, xenon can form fluorides and oxides with fluorine and oxygen, under very high pressures and temperatures.
Some of these compounds are xenon difluoride (XeF2), xenon tetrafluoride (XeF4), xenon hexafluoride (XeF6), and xenon tetroxide (XeO4). These compounds are either white or colorless crystal solids and are usually stable.
Do noble gases have any applications?
Regardless of the unreactive nature of noble gases, each of them has various applications across different industries.
Helium
Helium is a light gas. It is less dense than air which makes it a good choice for filling balloons to keep them afloat. Another use for helium gas is in cryogenics. Cooled helium is used for superconducting magnets in MRI machines and particle accelerators.
Some other applications are seen in gas chromatography, where it is used as a carrier gas to separate and analyze chemical compounds in a mixture; making helium-oxygen mixtures to treat patients with respiratory conditions; for propelling spacecraft and rockets; and in ionization detectors.
Neon
Neon gas in its excited state emits a bright, colorful glow that is used for illuminated signs, advertising, and decorative lighting.
Argon
Argon is a common shielding gas used in welding. It is used in gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) to protect the welding areas from atmospheric gases like oxygen and nitrogen which can cause contamination and ruin the weld.
Krypton
Krypton lasers are used in scientific research, medical applications, laser surgery, and laser light shows.
Xenon
Most high-intensity discharge (HID) lamps are made with xenon. They produce very bright and white light, which makes them an excellent choice for automobile headlights, stadium lighting, and movie projectors.
Radon
Radon is not a radioactive element, but it finds application in radioactivity, especially for cancer treatment. This gas is not very abundant in nature. It is usually generated artificially for use in the treatment of cancerous cells.
FAQs
Why are noble gases called noble?
Noble gases are termed noble because they are unreactive. They rarely bond and form compounds with other elements of the periodic table.
Are noble gases abundant in nature?
Noble gases are not so abundant in nature, and that is why they are called rare gases. However, they are present in the atmosphere in a fair percentage. Helium is the most abundant noble gas in the atmosphere. The abundance of noble gases reduces as you go down the group.
Can other elements behave like noble gases?
Other elements of the periodic table must gain one or more electrons to attain octet and become like the nearest noble gas. For instance, chlorine, a member of the halogen family must gain one electron to attain octet to behave like argon, the nearest noble gas.
Conclusion
Noble gases are truly noble, separating themselves from other elements of the periodic table with their complete octet structure. There are some exceptions to their reactivity, but they have perfectly managed their renowned stability regardless.
Moreover, they still find valuable applications. Helium balloons, neon signs, argon for welding, xenon in high-intensity discharge lamps, and krypton in laser technology. These elements are indeed applaudable.
Additionally, learn about the properties of transition metals – another family of wonderful elements.
Thanks for reading.