Skip to content

Argon [Ar] – Element Details, History, Atomic Structure, Facts, Properties, Electronic Configuration, Atomic Spectrum, Uses.


Argon is 18th element of Periodic table with atomic number 18, atomic weight 32.065. Sulfur,  symbol ‘Ar’, has a Face Centered Cubic structure and Colorless color. Argon is a Noble Gas element. It is part of group 18 (helium family or neon family) . Know everything about Argon Facts, Physical Properties, Chemical Properties, Electronic configuration, Atomic and Crystal Structure.  

History of Argon

They discovered the gas by comparing the molecular weights of nitrogen prepared by liquefaction from air and nitrogen prepared by chemical means. It is the first noble gas to be isolated.

The element Argon was discovered by Lord Rayleigh and W. Ramsay in 1894 in United Kingdom. Argon derived its name from the Greek word argos, meaning ‘idle’.

How to Locate Argon on Periodic Table

Periodic table is arranged by atomic number, number of protons in the nucleus which is same as number of electrons. The atomic number increases from left to right. Periodic table starts at top left ( Atomic number 1) and ends at bottom right (atomic number 118). Therefore you can directly look for atomic number 18 to find Argon on periodic table.

Another way to read periodic table and locate an element is by using group number (column) and period number (row). To locate Argon on periodic table look for cross section of group 18 and period 3 in the modern periodic table.

Argon Facts

Atomic Symbol
Atomic Number
Atomic Weight
Noble Gas
Group in Periodic Table
Group Name
helium family or neon family
Block in Periodic Table
Period in Periodic Table
Electronic Configuration
[Ne] 3s2 3p6
Melting Point
83.8 K
Boiling Point
87.3 K
Electronic Shell Structure
[2, 8, 6]
CAS Number

Argon Atomic Structure and Orbital Properties

Argon atoms have 18 electrons and the electronic shell structure is [2, 8, 8] with Atomic Term Symbol (Quantum Numbers) 1S0.

Element Properties

Atomic Number
Number of Protons
Mass Number
Number of Neutrons
Shell structure (Electrons per energy level)
[2, 8, 8]
Electron Configuration
[Ne] 3s2 3p6
Valence Electrons
3s2 3p6
Oxidation State
Atomic Term Symbol (Quantum Numbers)


Atomic Structure of Argon

Atomic Radius
71 pm (0.71 Å)
Atomic Radius Empirical
71 pm (0.71 Å)
Atomic Volume
22.4134 cm3/mol
Covalent Radius
97 pm (0.97 Å)
Van der Waals Radius
188 pm
Neutron Cross Section
Neutron Mass Absorption

Crystal Structure of Argon

The solid state structure of Argon is Face Centered Cubic.

The Crystal structure can be described in terms of its unit Cell. The unit Cells repeats itself in three dimensional space to form the structure.

The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a[525.6 pm]b[525.6 pm] and c[525.6 pm]) and the angles between them Lattice Angles (alpha[π/2], beta[π/2] and gamma[π/2])

The positions of the atoms inside the unit cell are described by the set of atomic positions ( xi, yi, zi) measured from a reference lattice point.

The symmetry properties of the crystal are described by the concept of space groups. All possible symmetric arrangements of particles in three-dimensional space are described by the 230 space groups (219 distinct types, or 230 if chiral copies are considered distinct.

Space Group Name

Oxidation States

Crystal Structure

Fm_ 3m

Space Group Number

Face Centered Cubic

Ground State Electronic Configuration of Argon - neutral Argon atom

Abbreviated electronic configuration of Argon

The ground state abbreviated electronic configuration of Neutral Argon atom is [Ne] 3s2 3p6. The portion of Argon configuration that is equivalent to the noble gas of the preceding period, is abbreviated as [Ne]. For atoms with many electrons, this notation can become lengthy and so an abbreviated notation is used. This is important as it is the Valence electrons 3s2 3p6, electrons in the outermost shell that determine the chemical properties of the element.

Unabbreviated electronic configuration of neutral Argon

Complete ground state electronic configuration for the Argon atom, Unabbreviated electronic configuration

1s2 2s2 2p6 3s2 3p6

Electrons are filled in atomic orbitals as per the order determined by the Aufbau principle, Pauli Exclusion Principle and Hund’s Rule.

  • As per the Aufbau principle the electrons will occupy the orbitals having lower energies before occupying higher energy orbitals. According to this principle, electrons are filled in the following order: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
  • The Pauli exclusion principle states that a maximum of two electrons, each having opposite spins, can fit in an orbital.
  • Hund’s rule states that every orbital in a given subshell is singly occupied by electrons before a second electron is filled in an orbital.

Regulatory and Health - Health and Safety Parameters and Guidelines

CAS Number
RTECS Number
EU Number
DOT Hazard Class
DOT Numbers
NFPA Fire Rating
NFPA Hazards
Autoignition Point
NFPA Health Rating
NFPA Reactivity Rating

Argon Chemical Properties : Argon Ionization Energies and electron affinity

0 kJ/mol

Argon Physical & Elastic Properties

0.001784 g/cm3
Molar Volume
22.4134 g/cm3
Young Modulus
Shear Modulus
Bulk Modulus
Poisson Ratio

Argon Electrical Properties

Electrical Conductivity
Superconducting Point

Argon Magnetic Properties

Magnetic Type
Curie Point
Mass Magnetic Susceptibility
-6e-9 m3/kg
Molar Magnetic Susceptibility
-2.4e-10 m3/mol
Volume Magnetic Susceptibility

Argon Thermal Properties

Melting Point
83.8 K (-189.35°C, -308.8299999999999 °F)
Boiling Point
87.3 K (-185.85°C, -302.5299999999999 °F)
Critical Temperature
150.87 K
Superconducting Point

Use of Argon

Argon is in many cases utilized when a latent air is required. It is utilized in this manner for the development of titanium and other responsive components. It is likewise utilized by welders to safeguard the weld region and in brilliant lights to prevent oxygen from eroding the fiber.

106. Seaborgium [Sg]