de en fr hr it es
Neighborhood
F
9
Ne
10
Na
11
Cl
17
Ar
18
K
19
Br
35
Kr
36
Rb
37

 

Periodic table

de  German

Argon

en  English

Argon

fr  French

Argon

hr  Croatian

Argon

it  Italian

Argo

es  Spanish

Argón

 

Ar
Ar
Argonum

 

Atomic number:18

Group numbers:18

Period:3

Electronic configuration:[Ne] 3s2 3p6

Formal oxidation number:0

Electronegativities:-

Atomic radius / pm:188

Relative atomic mass:39.948 ± 0.001

 

Argon was discovered by Lord Raleigh and Sir William Ramsay (GB) in 1894. The origin of the name comes from the Greek word argos meaning inactive. It is a colourless and odourless noble gas, chemically inert. Argon is the third most abundant element in the earth's atmosphere and makes up about 1%. Argon is continuously released into the air by decay of radioactive potassium-40. Pure form is obtained from fractional distillation of liquid air. It is used in lighting products, and is often used in filling incandescent light bulbs. Some is mixed with krypton in fluorescent lamps. Crystals in the semiconductor industry are grown in argon atmospheres.

PHYSICAL PROPERTIES

Density / g dm-3:1656 (40 K)

 1.784 (273 K)

Molar volume / cm3mol-1:24.12 (40 K)

 22392.38 (273 K)

Electrical resistivity / μΩcm:- (20 °C)

THERMAL PROPERTIES

Thermal conductivity / W m-1K-1:0.0179

Melting point / °C:-189.34

Boiling point / °C:-185.89

Heat of fusion / kJ mol-1:1.21

Heat of vaporization / kJ mol-1:6.53

Heat of atomization / kJ mol-1:0

IONIZATION ENERGIES

First ionization energy / kJ mol-1:1520.58

Second ionization energy / kJ mol-1:2665.88

Third ionization energy / kJ mol-1:3930.84

ABUNDANCE OF ELEMENTS

in the atmosphere / ppm:9300

in the Earth's crust / ppm:1.2

in the oceans / ppm:0.6

CRYSTALLOGRAPHIC DATA

face-centered cubic

Crystal structure:

face-centered cubic

Unit-cell dimensions / pm:

a=531.088

Space group:

Fm3m

ISOTOPES

IsotopeRelative atomic massMass percent (%)
36Ar35.9675463(3)0.337(3)
37Ar36.9667759(3)*
38Ar37.9627322(5)0.063(1)
39Ar38.964313(5)*
40Ar39.962383123(3)99.600(3)

REDUCTION POTENTIALS

Balanced half-reaction Eo / V

 

17 Chlorine <=
18 Argon
=> 19 Potassium