argon: Quick Facts

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Oct. 14, 2026

Facts

Also Known As	Ar

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Diagram showing the chemical properties of argon from the periodic table, including atomic number 18, symbol Ar, atomic weight range, electron configuration, noble gas classification, face-centered cubic crystal structure, and gaseous state at room temperature.

Argon isolation

Line graph showing the first ionization energies of the elements as a function of atomic number, with peaks at noble gases like helium, neon, argon, krypton, xenon, and radon, and labeled elements at key points.

argon phase diagram

Figure 1: The four stable geometric structures of the seven-atom cluster of argon, in order of increasing energy: (A) A pentagonal bipyramid. (B) A regular octahedron with one face capped by the seventh atom. (C) A regular tetrahedron with three of its faces capped by other atoms. (D) A trigonal bipyramid with two of its faces capped by other atoms; although this has the highest energy of the four structures, it is very close in energy to the tricapped tetrahedron.

Figure 2: The four lowest-energy structures of the 13-atom cluster of argon.

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Topics

argon-40 air chemical element noble gas hydrogen carbon sodium nitrogen sulfur phosphorus boron iodine fluorine zinc

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