![](http://www.alamy.com/thumbs/6/839BF3D2-091F-498B-BC1E-CB621648A03E/2ACT1EB.jpg)
Argon (Ar). Diagram of the nuclear composition, electron configuration, chemical data, and valence orbitals of an atom of argon-40 (atomic number: 18)
Argon (Ar). Diagram of the nuclear composition, electron configuration, chemical data, and valence orbitals of an atom of argon-40 (atomic number: 18), the most common terrestrial isotope of this element. The nucleus consists of 18 protons (red) and 22 neutrons (orange). 18 electrons (white) occupy shells (rings); eight fill the outer (third) electron shell in what is a very stable configuration. The stability of an element's outer (valence) electrons determines its chemical and physical properties. Argon is a noble gas in group 18, period 3, and the p-block of the periodic table. An inert gas formed from the decay of potassium-40, it is used in fluorescent lighting and lasers.
Size: 5197px × 5008px
Photo credit: © CARLOS CLARIVAN/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: -atomic, -block, -metal, -metallic, -metals, -reactive, 3, 18, 3p, 3p6, 3s, 3s2, amu, ar, argon, argon-40, atom, atomic, background, black, block, chemical, chemistry, configuration, data, diagram, electron, electronic, electrons, element, elemental, elements, energy, function, gas, gaseous, gases, group, illustration, inert, isotope, level, levels, neutron, neutrons, noble, nonmetal, nonmetallic, nonmetals, nuclear, nucleon, nucleons, nucleus, number, orbital, orbitals, period, physical, pm, properties, property, proton, quantum, radius, shell, shells, simple, structural, structure, subatomic, subshell, subshells, symbol, types, unreactive, valence, wave, weight