Element Information, Facts, Properties, Trends, Uses, Comparison with other elements
Argon is a chemical element with symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a Noble Gas. Argon is the third most common gas in the Earth's atmosphere, at 0.934% (9,340 ppmv), making it over twice as abundant as the next most common atmospheric gas, water vapor (which averages about 4000 ppmv, but varies greatly), and 23 times as abundant as the next most common non-condensing atmospheric gas, carbon dioxide (400 ppmv), and more than 500 times as abundant as the next most common Noble Gas, neon (18 ppmv).
It belongs to group 18 of the periodic table having trivial name noble gases, aerogens.
Read key information and facts about element Argon
|Phase||Gas (Monoatomic Gas )|
|Appearance||colorless gas exhibiting a lilac/violet glow when placed in a high voltage electric field|
|Group in Periodic Table||18|
|Group Name||helium family or neon family|
|Period in Periodic Table||period 3|
|Block in Periodic Table||p -block|
|Electronic Configuration||[Ne] 3s2 3p6|
|Electronic Shell Structure (Electrons per shell)||2, 8, 8|
|Melting Point||83.8 K|
|Boiling Point||87.3 K|
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.
The element Argon was discovered by Lord Rayleigh and W. Ramsay in year 1894 in United Kingdom. Argon was first isolated by Lord Rayleigh and W. Ramsay in 1894. Argon derived its name from the Greek word argos, meaning 'idle'.
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.
Argon Presence: Abundance in Nature and Around Us
The table below shows the abundance of Argon in Universe, Sun, Meteorites, Earth's Crust, Oceans and Human Body.
|ppb by weight (1ppb =10^-7 %)||ppb by atoms (1ppb =10^-7 %)|
|Abundance in Universe||200000||6000|
|Abundance in Sun||70000||2000|
|Abundance in Meteorites||-||-|
|Abundance in Earth's Crust||1500||780|
|Abundance in Oceans||450||70|
|Abundance in Humans||-||-|
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.
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)
|525.6 pm||525.6 pm||525.6 pm|
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 ( 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||Fm_ 3m|
|Oxidation States||Space Group Number||225|
|Crystal Structure||Face Centered Cubic|
Argon Atomic and Orbital Properties
Argon atoms have 18 electrons and the electronic shell structure is [2, 8, 8] with Atomic Term Symbol (Quantum Numbers) 1S0.
|Number of Electrons (with no charge)||18|
|Number of Protons||18|
|Number of Neutrons||22|
|Shell structure (Electrons per energy level)||2, 8, 8|
|Electron Configuration||[Ne] 3s2 3p6|
|Valence Electrons||3s2 3p6|
|Main Oxidation States||0|
|Atomic Term Symbol (Quantum Numbers)||1S0|
Bohr Atomic Model of Argon - Electrons per energy level
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.
Atomic Structure of Argon
Argon atomic radius is 71 pm, while it's covalent radius is 97 pm.
|Atomic Radius Calculated|
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||0.65|
|Neutron Mass Absorption||0.0006|
Atomic Spectrum of Argon
Argon Chemical Properties: Argon Ionization Energies and electron affinity
The electron affinity of Argon is 0 kJ/mol.
Ionization Energy of Argon
Refer to table below for Ionization energies of Argon
|Ionization energy number||Enthalpy - kJ/mol|
Argon Physical Properties
Refer to below table for Argon Physical Properties
|Molar Volume||22.4134 cm3/mol|
Hardness of Argon - Tests to Measure of Hardness of Element
Argon Electrical Properties
Argon is Conductor of electricity. Refer to table below for the Electrical properties ofArgon
Argon Heat and Conduction Properties
|Thermal Conductivity||0.01772 W/(m K)|
Argon Magnetic Properties
|Mass Magnetic Susceptibility||-6e-9 m3/kg|
|Molar Magnetic Susceptibility||-2.4e-10 m3/mol|
|Volume Magnetic Susceptibility||-1.07e-8|
Optical Properties of Argon
Acoustic Properties of Argon
|Speed of Sound||319 m/s|
Argon Thermal Properties - Enthalpies and thermodynamics
Refer to table below for Thermal properties of Argon
|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|
Enthalpies of Argon
|Heat of Fusion||1.18 kJ/mol|
|Heat of Vaporization||6.5 kJ/mol|
|Heat of Combustion||-|
Argon Isotopes - Nuclear Properties 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.
|Isotope||Z||N||Isotope Mass||% Abundance||T half||Decay Mode|