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The Element Argon: Structure and Properties

The element Argon is the eighteenth heaviest element. Each Argon atom has 18 protons in the nucleus and 18 electrons orbiting that nucleus. The most common form of Argon also has 22 Neutrons in the nucleus. Argon belongs to the group of elements called the Noble Gases. It is stable in its natural form and so does not react with other elements Argon atoms are found singly in nature and in gas form.

Argon has many commercial uses. It is produced in commercial quantities through the fractional distillation of liquid air along with Nitrogen and Oxygen gases, making it the cheapest and easiest Noble Gas to obtain in bulk quantities, as it makes up just under 1% of the Earth's atmosphere. It is commonly used in fire extinguishers for sensitive electronic equipment. It is also used in many applications that require an non-reactive gas atmosphere such as the interior of incandescent light bulbs, storing reactive metals in solid form, preventing oxidation of food products and as a shielding atmosphere for welding.

Isotopes of Argon
There are 23 different possible isotopes of the element Argon, each with a differing number of neutrons in the nucleus of the Argon atom. The lightest of these is 30-Argon which contains the standard 18 protons and 12 neutrons, making a total of 30 nuclear components. The heaviest is 53-Argon which has 18 protons and 35 neutrons. All these isotopes have the same chemical properties due to them having the same number of electrons. The differences in nuclear structure result in these isotopes either being stable or breaking down radioactively to form other elements.
Only three of the Argon isotopes are stable. These are the 36-, 38- and 40-Argon isotopes that have 18, 20 and 22 neutrons respectively. The most common of these is 40-Argon which makes up 99.6% of all naturally occurring Argon atoms in a sample. The only radioactive isotope that has any degree of stability is 39-Argon, which has a half life of 269 years. It is mainly produced in the atmosphere through the interaction of cosmic rays with 40-Argon.
Electron Structure of Argon

Argon's 18 electrons are arranged into three full shells. We can find the electron details of Argon by placing 18 electrons into the subshell filling pattern, which gives the configuration 1s2 2s2 2p6 3s2 3p6. This is shown in picture form below. From this we get the electron dot diagram of Argon as seen to the right. It clearly shows all 8 electron sites being filled, which is why Argon atoms are non-reactive under normal circumstances. This is the same outer shell electron configuration as the next lightest Noble Gas, the element Neon.

The Electronegativity of Argon
An atom of the element Argon has a complete outer shell of electrons, and therefore has no ability to attract or lose electrons. This results in it having no electronegativity value at all. Only members of the Noble Gas group of elements have this property, with the single exception of the element Xenon.

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