Elements
18

Ar

Argon

Argon (Ar) exists as a colourless, odourless gas and is chemically inert. It has the atomic number 18 in the periodic table and belongs in Group 18, the Noble Gases. It is a non metal with the symbol Ar.

Argon was the first noble gas that was discovered by Sir Henry Cavendish through his work to identify an unknown compound in air. After identifying Oxygen, he proceeded to react Oxygen and Nitrogen in the air to form Nitrous oxides. After chemical treatment with Sodium hydroxide a small bubble of gas remained that Cavendish identified as an unreactive gas, at the time this was Argon. It was not until 1895 and the use of spectrum analysis that Lord Rayleigh and William Ramsey discovered the unique spectrum of Argon, named after the Greek ‘Argos’ meaning inactive. Argon has a wide variety of uses in the metal industry due to its inert behaviour. It is often used in welding and cutting of metals and also to produce protective layers on metals such as Titanium. Originally, the symbol for Argon was A until 1957 when IUPAC decided to change the symbol to A. Argon makes up 1% of the earths atmosphere but the vast majority of Argon comes from the radioactive decay of Potassium-40. It is located in Group 18 as a non metal gas which is odourless and colourless. It has a melting point of -189°c and a boiling point of -185°c.

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FAQ's

What is the Melting Point for Argon?

Argon has a Melting Point of -189.2°F, meaning at -189.2°F it will turn to a liquid.

What is the Boiling Point for Argon?

Argon has a Boiling Point of -185.7°F, meaning at -185.7°F it will turn to a Gas.

What is the Electronegativity of Argon?

Argon's Electronegativty is 0. Electronegativity is a measure of how strongly atoms attract bonding electrons to themselves.

What is the Heat of Vaporization of Argon?

Argon has a Heat of Vaporization of 6.447 kJ/mol.

Uses

Used in lighting products. It is often used in filling incandescent light bulbs. Some is mixed with krypton in fluorescent lamps. Crystals in the semiconductor industry are grown in argon atmospheres.

Sources

Continuously released into the air by decay of radioactive potassium-40. Pure form is obtained from fractional distillation of liquid air.

18
Protons
18
Electrons
22
Neutrons

Ar

Element Symbol
Ar
Atomic Weight
39.948
Atomic Number
18
State
Gas
Melting Point
Unknown
-189.2
°C
Boiling Point
-185.7
Unknown
°C
Heat of Vaporization
6.447
Unknown
kJ/mol
Crystal Structure
Cubic: Face centered
Thermoconductivity
0.0001772
Unknown
W/cmK
Shells
2,8,8
Group
Noble Gas
Period
3
Block
P Block
Orbitals
[Ne] 3s2 3p6
Coefficient of Thermal Expansion
618 10^-6 K^-1
Covalent Radius
0.98 Å
Density at 293K
0.0017824 g/cm³
Electrical Conductivity
--
First Ionization Potential
15.7596 V
Second Ionization Potential
27.629 V
Third Ionization Potential
40.74 V
Ionic Radius
--
Oxydation States
0
Lattice Parameter
--
Lattice Parameter 2
--
Lattice Parameter 3
5.2735 Å
Pronounced

AR-gon

Discovered by

Sir William Ramsey, Baron Rayleigh

Discovery date

1894

Orbital configuration
2,8,8

Download the Periodic Table

Explore Other Noble Gass

4.003
2

He

Helium
83.798
36

Kr

Krypton
222
86

Rn

Radon
131.293
54

Xe

Xenon
294
118

Og

Oganesson
20.18
10

Ne

Neon
Noble gases are seven chemical elements that make up group 18 (VIIIa) of the periodic table: helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn) and oganesson (Og). They are colorless, odorless, tasteless, nonflammable gases.
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