argon

• Description
• General information
• Physical data
• Radii
• Electronegativities
• Solid state structure
• Temperatures
• Enthalpies
• Ionization Enthalpies
• Isotopes
• Further information

Description

Argon is colourless and odourless. Argon is very inert and is not known to form true chemical compounds. It makes a good atmosphere for working with air-sensitive materials since it is heavier than air and less reactive than N₂.

General information

Discoveror: Sir William Ramsay, Lord Rayleigh
Date discovered: 1894
Discovered at: Scotland
Meaning of name: From the Greek word "argos" meaning "inactive"

Physical data

Standard state: gas at 298 K
Colour: colourless
Density of solid at ambient temperature/kg m^-3: no data
Molar volume/cm³: 22.56

Radii /pm

Atomic: 71
Covalent (single bond):
Pauling radius for the ion [Ar]^-: no data

Valence shell orbital radius maxima (R_max)

orbital	s	p	d	f
radius	62.6	68.8	no data	no data

Electronegativities

Both values are quoted on the Pauling scale.

Pauling: no data
Allred Rochow: 3.20

Crystal Structure

structure: ccp (cubic close-packed)

The following CrystalMaker image represents the solid state structure. For most elements, the most stable allotrope is illustrated. Try WebElements version 2 for interactive virtual reality and CHIME images.

Temperatures (/K)

melting point: 83.8
boiling point: 87.3

Enthalpies /kJ mol^-1

fusion: 1.18
vaporization: 6.5

single bond enthalpies:

Ar-F	Ar-Cl	Ar-Br	Ar-I	Ar-Ar
no data	no data	no data	no data	4.73

Ionization enthalpies /kJ mol^-1

Number	Enthalpy
1st	1520.5
2nd	2665.8
3rd	3931
4th	5771
5th	7238
6th	8780
7th	12000
8th	13844

Isotopes

This section gives some data for naturally occurring isotopes.

Nominal mass	Accurate mass	% natural abundance
36Ar	35.96754552 (29)	0.337 (3)
38Ar	37.9627325 (9)	0.063 (1)
40Ar	39.9623837 (14)	99.600 (3)

Further Information

• Additional information about WebElements 1.2.2
• This is a licensed copy (here is the full list) of WebElements 1.2.2 and contains a subset of the material contained within the main version of WebElements (version 2)
• For further information please try WebElements version 2
• Sheffield Chemdex: perhaps the largest internet chemistry directory
• Sheffield Chemputer: interactive chemistry calculators on the WWW