Ar - Argon

Argon is used in incandescent and fluorescent bulbs as a protective layer around the filament to keep oxygen from eroding it. It is also used as a protective shield in arc welding and semiconductor crystals.

The table below shows the abundance of Argon in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.

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.

Unit Cell Parameters

The unit cell is represented in terms of its lattice parameters, which are the lengths of the cell edges Lattice Constants (a, b and c)

and the angles between them Lattice Angles (alpha, beta and gamma).

The positions of the atoms inside the unit cell are described by the set of atomic positions ( x_i, y_i, z_i) 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	Fm_ 3m
Space Group Number	225
Crystal Structure	Face Centered Cubic
Number of atoms per unit cell	4

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

Atomic Number	18
Number of Electrons (with no charge)	18
Number of Protons	18
Mass Number	40
Number of Neutrons	22
Shell structure (Electrons per energy level)	2, 8, 8
Electron Configuration	[Ne] 3s2 3p6
Valence Electrons	3s2 3p6
Valence (Valency)	0
Main Oxidation States	0
Oxidation States	0
Atomic Term Symbol (Quantum Numbers)	1S0

Bohr Atomic Model of Argon - Electrons per energy level

n		s	p	d	f

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.

Atomic Structure of Argon

Argon atomic radius is 71 pm, while it's covalent radius is 97 pm.

Spectral Lines of Argon - Atomic Spectrum of Argon

A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from an excess or deficiency of photons in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to identify atoms and molecules.

Spectral lines are the result of interaction between a quantum system and a single photon. A spectral line may be observed either as an emission line or an absorption line.

Spectral lines are highly atom-specific, and can be used to identify the chemical composition of any medium. Several elements, including helium, thallium, and caesium, were discovered by spectroscopic means. They are widely used to determine the physical conditions of stars and other celestial bodies that cannot be analyzed by other means.

Emission spectrum of Argon

Absorption spectrum of Argon

The electron affinity of Argon is 0 kJ/mol.

Ionization Energy of Argon

Ionization energy is the amount of energy required to remove an electron from an atom or molecule.in chemistry, this energy is expresed in kilocalories per mole (kcal/mol) or kilojoules per mole (kJ/mol).

Refer to table below for Ionization energies of Argon

Refer to below table for Argon Physical Properties

Elastic Properties

Hardness of Argon - Tests to Measure of Hardness of Element

Argon Electrical Properties

Electrical resistivity measures element's electrical resistance or how strongly it resists electric current.The SI unit of electrical resistivity is the ohm-metre (Ω⋅m). While Electrical conductivity is the reciprocal of electrical resistivity. It represents a element's ability to conduct electric current. The SI unit of electrical conductivity is siemens per metre (S/m).

Argon is a -. Refer to table below for the Electrical properties of Argon

Argon Heat and Conduction Properties

Argon Magnetic Properties

Optical Properties of Argon

Acoustic Properties of Argon

Refer to table below for Thermal properties of Argon

Enthalpies of Argon

Argon has 24 isotopes, with between 30 and 53 nucleons. Argon has 3 stable naturally occuring isotopes.

Isotopes of Argon - Naturally occurring stable Isotopes: 36Ar, 38Ar, 40Ar.

The United States Department of Transportation (DOT) identifies hazard class of all dangerous elements/goods/commodities either by its class (or division) number or name. The DOT has divided these materials into nine different categories, known as Hazard Classes.

NFPA 704 is a Standard System for the Identification of the Hazards of Materials for Emergency Response. NFPA is a standard maintained by the US based National Fire Protection Association.

The health (blue), flammability (red), and reactivity (yellow) rating all use a numbering scale ranging from 0 to 4. A value of zero means that the element poses no hazard; a rating of four indicates extreme danger.

List of unique identifiers to search the element in various chemical registry databases