Is Argon a Noble Gas?

Argon is a colorless, odorless gas with atomic number 18 and the symbol Ar. It belongs to the 18th group and the 3rd period of the periodic table. Besides Nitrogen and Oxygen, it is the most abundant gas in the earth’s atmosphere.

Lord Rayleigh and Sir William Ramsay were the first to isolate Argon in 1984 from the sample of clean air. It is useful in multiple industrial processes like arc welding and cutting.

In this article, we will discuss the most searched questions related to Argon like-

• Nature of argon (inert or reactive)

• Electronic configuration of argon

• Reactivity of Argon

• Properties and uses of Argon

So, Is argon a noble gas? Yes, Argon is a noble gas because it has its octet already filled so, it does not tend to lose, gain or share an electron. Hence, it does not react with any other element under most conditions and is known as Noble or inert gas.

In general, atoms of all elements follow the octet rule and complete their shells by gaining, losing, or sharing electrons. 

What are Noble Gases?

There are seven chemical elements in the periodic table including, Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn), and Organesson (Og) that make up Group 18 (Noble gas).

In the theory of chemical bonding by Lewis and Kossel, the octet rule dictates the most stable arrangement for the valence shell of an atom.

Every atom can lose, gain or share electrons to have eight electrons in its outer shell.

However, in the case of noble gases, they already possess this arrangement. Their outer shells are completely filled so they do not bond to other atoms and remain noble or inert under most conditions.

General Properties of Noble Gases

• Completely filled outermost shells which give them little or no tendency to participate in chemical reactions.

• Monoatomic gases under standard conditions.

• Weak interatomic forces so they have very low melting and boiling points.

• Melting points and boiling points of noble are very close to each other indicating the liquid state of noble gases over a small temperature range only.

• Large ionization potential and negative electron affinity.

• Nearly Ideal gases under standard conditions.

Electronic Configuration of Noble Gases

The electronic configuration of an element represents the distribution of electrons in its atomic orbitals.

It provides insight into the number of valence electrons, period, block, and other chemical properties of elements.

Things to remember while writing noble configuration:

• Notation

Writing an electronic configuration starts with the shell number (1,2,3……) followed by name of subshells (s,p,d,f) and finally, a superscript indicates the total number of electrons in the subshell.

A short-hand notation or noble gas configuration of an element uses noble gas of the previous period as a substitution for inner-shell electrons of the element having the same configuration as that of the noble gas
For example,

Electron configuration of Sodium is 1s2 2s2 2p6 3s1

Electron configuration of Neon is 1s2 2s2 2p6

A short-hand notation of Sodium is [Ne] 3s1

• Number of maximum electrons accommodate in subshells

The maximum number of electrons that can be accommodated in s, p, d, f subshells are 2, 6, 10, and 14 respectively.

• Filling of atomic orbitals

Following the Aufbau principle, orbitals with lower energy get filled before orbitals with higher energy. The order of filling up electrons in atomic orbitals is as follows:

It is important to note that elements like copper and chromium disobey the Aufbau principle while filling their atomic orbitals.

These exceptions can be justified by the stability of partially filled and completely filled orbitals.

Why is Argon a Noble Gas?

In an atom, electrons normally exist in energy shells (K, L, M..) and each energy level can accommodate only a certain number of electrons. For instance, K shell can have 2 electrons, L shell can have 8 electrons.

According to the octet rule, the outermost shell must contain 8 electrons to be energetically stable. Therefore, atoms of elements lose, gain or share their valence electrons to attain octet.

In the case of noble gases, their outermost shells have already complete octet.

For example, Neon, E.C is 1s2 2s2 2p6

Its outermost shell (n =2) has 2+6 = 8 electrons

Now, electronic configuration of Argon is 1s2 2s2 2p6 3s2 3p6 where,

K shell (n = 1) has 2 electrons

L shell (n = 2) has 8 electrons

M shell, outermost shell (n = 3) has 2+6 = 8 electrons (octet)

The octet in the outermost shell is the most stable electronic configuration. As a result, losing, gaining, or sharing electrons is not necessary for Argon to attain stability.

Like other noble gases, Argon is highly stable as monoatomic and resists bonding with other elements.

Is Argon Reactive?

Argon is considered to be non-reactive and inert because of some basic properties of noble gases like

• Completely filled valence shell orbitals

• The high value of ionization potential and negative electron affinity

Ionization potential is the amount of energy required to remove a valence electron from an isolated atom to form a positive ion.

Whereas, electron affinity is the amount of energy released when an electron is added to a neutral atom to form a negative ion.

However, the discovery of Argon Flurohydride (HArF) in August 2000 showed that argon reacts with a small amount of Hydrogen fluoride with Caesium iodide to form this compound.

The discovery indicates that heavy noble gases like Argon can form weakly bound compounds as ionization potential decreases down the group due to an increase in size.

Other argon compounds are (Ar(H2)2), Ar1C60, ArNH+ etc.

Why Argon is used in Bulb?

Have you seen incandescent light bulbs at your home?

Light bulbs are filled with inert gas like Argon and mercury vapors. Argon is an inert gas so it does not react with tungsten and therefore does not affect the working of the filament.

In fact, it prevents the tungsten filament from oxidation at a high temperature which increases the light bulb life.

Properties of Argon

Uses of Argon

Manufacturing Industry

Argon is one of the cheapest and best alternatives for nitrogen to create an inert atmosphere in some industrial processes such as gas metal arc welding, gas tungsten arc welding, and casting.

It is used in making titanium and other reactive elements

Within the manufacturing of steel and aluminum, argon reduces the loss of chromium to meet the desired carbon content at a lower temperature.

Within the manufacturing of aluminum, argon removes hydrogen and other dissolved gases.

It is used in growing crystals of silicon and germanium.

Lighting

Argon is widely used in incandescent light bulbs to prevent the oxidation of tungsten filament at high temperatures.

When electricity is passed in gas-discharge lamps through Argon, it produces lilac/violet light.

Healthcare industry

Blue argon lasers are helpful in surgical equipment.

Liquid argon is used in Argon cryosurgery for the treatment of damaged tissues.

Food and drink industry

Being inert and denser than air, argon forms a layer above the liquid in open wine and liquid bottles that prevent them from souring and oxidation.

Preservation

Argon can increase shelf-lives of the content in the packaging material by replacing oxygen and moisture-containing air.

It provides a protective atmosphere against degradation, oxidation, and damage. So, Argon is used in the preservation of old documents, high-purity chemicals during their storage.

Other Uses

Liquid argon plays an important role in scientific researches for dark matter

Argon is used as drysuit insulation for scuba diving because of its inert nature and low thermal conductivity

Argon is used in cinematography

Argon is used in fire extinguishing

Argon ion laser is used in high-speed printing and laser shows

Conclusion

Argon is the third-most abundant, colorless, odorless, and non-toxic gas with atomic number 18. The gas derived its name “Argon” from a Greek word for άρόγν, meaning “lazy”, reflecting its nature of being unreactive and inert.

It belongs to group 18 of the periodic table and its electronic configuration is 1s2 2s2 2p6 3s2 3p6 or, [Ne] 3s2 3p6. Its outermost shell is completely filled with 8 electrons, the most stable electronic configuration therefore Argon is a noble gas

It has high ionization enthalpy and negative electron affinity, making it difficult to react with one another or any other atom by losing, gaining, or sharing electrons. However, a few compounds of Argon are known like Argon Flurohydride (HArF), stable at very low temperature

Its inert properties enhance its applications in multiple industries like manufacturing, healthcare, research, Food and drink industry, and more. It is widely used in incandescent light bulbs to slow down the evaporation of the tungsten filament.