Symbol	Ar
Atomnummer	18
Gruppe	18 (Ædelgasser)
Periode	3
Blok	p
Klassifikation	Ædelgasser

Udseende	Colorless gas exhibiting a lilac/violet glow when placed in a high voltage electric field
Farve	Farveløs

Antal protoner	18 p+
Antal neutroner	22 n0
Antal elektroner	18 e-

Fra Wikipedia, den gratis encyklopædiArgon er et grundstof med atomnummer 18 i det periodiske system og symbolet Ar. Argon er det tredje grundstof i hovedgruppe 8, ædelgasserne. Der er lidt mindre end 1 % argon i jordens atmosfære, og dermed er det den mest almindelige ædelgas på jorden.

Fase ved STP	Gas
Massefylde	1.784 g/cm3
Atommasse	39.792 u

Smeltepunkt	83.81 K -189.34 °C -308.812 °F
Kogepunkt	87.302 K -185.848 °C -302.5264 °F
Fordampningsvarme	6.506 kJ/mol

Elektronegativitet (Pauling Scale)	-
Elektronaffinitet	-96 kJ/mol
Oxidationstrin	0
Ioniseringsenergier	1520.6 kJ/mol 2665.8 kJ/mol 3931 kJ/mol 5771 kJ/mol 7238 kJ/mol 8781 kJ/mol 11995 kJ/mol 13842 kJ/mol 40760 kJ/mol 46186 kJ/mol 52002 kJ/mol 59653 kJ/mol 66199 kJ/mol 72918 kJ/mol 82473 kJ/mol 88576 kJ/mol 397605 kJ/mol 427066 kJ/mol

Elektronkonfiguration Kortfattet konfiguration	[Ne] 3s2 3p6
Elektronkonfiguration Fuld konfiguration	1s2 2s2 2p6 3s2 3p6
Elektronkonfigurationsdiagram	1s2 2s2 2p6 3s2 3p6
Elektroner pr. Skal	2, 8, 8
Valenselektroner	8
Valency-elektroner	0
Bohrs atommodel	Figur: Skaldiagram af Argon (Ar) atom.
Orbital diagram	1s 2s 2p 3s 3p

Opdagelse og første isolation

Lord Rayleigh, William Ramsay (1894)

Opdagelse af argon Argon (Greek ἀργόν, neuter singular form of ἀργός meaning "lazy" or "inactive") is named in reference to its chemical inactivity. This chemical property of this first noble gas to be discovered impressed the namers. An unreactive gas was suspected to be a component of air by Henry Cavendish in 1785. Argon was first isolated from air in 1894 by Lord Rayleigh and Sir William Ramsay at University College London by removing oxygen, carbon dioxide, water, and nitrogen from a sample of clean air. They first accomplished this by replicating an experiment of Henry Cavendish's.

CAS Number	7440-37-1
ChemSpider ID	22407
EC number	231-147-0
PubChem CID Number	23968