Noble Gases: What They Are, Properties and Applications
What Are Noble Gases?
Noble Gases, also called Rare Gases, belong to Group 18 of the Periodic Table (formerly Group 0 or 8A). They are known for having low chemical reactivity, meaning they hardly combine with other elements. This is due to their completely filled valence electron shell, which makes them naturally stable.
Discovery of Noble Gases
The first evidence of the existence of these gases came from spectrographic studies of sunlight. This is how the presence of helium (He) was discovered in the Sun, even before it was identified on Earth. From then on, other noble gases were isolated and studied, confirming the existence of a group of elements with unique properties.
Which Are the Noble Gases?
The elements that make up the noble gases group are:
- Helium (He)
- Neon (Ne)
- Argon (Ar)
- Krypton (Kr)
- Xenon (Xe)
- Radon (Rn)
- Oganesson (Og) – formerly known as Ununoctium (Uuo)
⚠️ Note: Unlike what many think, Ununoctium has already been officially named Oganesson (Og) in honor of the scientist Yuri Oganessian. It occupies the position below Radon in the periodic table.
Physical and Chemical Properties
- Physical state: all noble gases are gaseous under standard conditions (25 °C and 1 atm).
- Low melting and boiling points: due to weak interatomic attractive forces.
- Chemical reactivity: very low, but not nonexistent. Heavier elements such as xenon and radon can form compounds, especially with highly electronegative elements like fluorine and oxygen.
- Colorless and odorless: these gases are invisible and odorless.
- Non-flammable: they do not catch fire nor support combustion.
Applications of Noble Gases
Despite their low reactivity, noble gases have numerous applications in daily life and industry:
- Helium (He): used in balloons, airships, deep-sea diving (breathing mixtures), and MRI equipment.
- Neon (Ne): famous for neon lamps and illuminated signs.
- Argon (Ar): widely used in welding and incandescent bulbs to prevent filament oxidation.
- Krypton (Kr) and Xenon (Xe): used in special lamps, lasers, and high-intensity lighting systems.
- Radon (Rn): although radioactive and hazardous, it was once used in controlled medical treatments.
- Oganesson (Og): due to its extreme instability, it has no practical applications — it is only studied in laboratories.
Importance in the Periodic Table
Noble gases are fundamental for the understanding of electronic stability and the octet rule, the basis of chemical bonding theory. They represent the tendency of atoms to seek electronic stability similar to these elements.
FAQ – Frequently Asked Questions about Noble Gases
Which are the noble gases?
The noble gases are: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).
Why are noble gases not very reactive?
They are not very reactive because they have a completely filled valence electron shell, which makes them stable and less likely to form chemical bonds.
Where are noble gases found?
They are mainly present in the Earth’s atmosphere (in small amounts), inside the Earth, and even in the Sun and other stars.
What are noble gases used for?
Each gas has its own application:
- Helium: balloons, airships, diving, and MRI machines.
- Neon: illuminated signs.
- Argon: welding and light bulbs.
- Krypton and Xenon: special lighting and lasers.
- Radon: once used in medicine, but it is dangerous.
- Oganesson: only studied in laboratories.
What makes noble gases different from other chemical elements?
The main difference is their electronic stability. They almost never need to react to reach the “ideal state,” unlike most elements in the Periodic Table.
Does Ununoctium still exist?
The name Ununoctium (Uuo) was temporary. Today the element is officially called Oganesson (Og), in honor of the physicist Yuri Oganessian.