chlorine - argon - potassium

[Ne] 3s 2 3p 6

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name, symbol, ordinal number argon, acre, 18
series Noble gases
group, period, block 18 (VIIIA), 3, p
appearance colorless
proportion at the Earth's shell 4 · 10 -4 %
atomic mass 39.948
atomic radius (computed) - (71) pm
Kovalenter radius 97 pm
van the Waals radius 188 pm
Elektronenkonfiguration [Ne] 3 s 2 3p 6
electrons per energy level 2, 8, 8
1. Ionization energy 1520.6 kJ/mol
2. Ionization energy 2665.8 kJ/mol
3. Ionization energy 3931 kJ/mol
4. Ionization energy 5771 kJ/mol
5. Ionization energy 7238 kJ/mol
6. Ionization energy 8781 kJ/mol
7. Ionization energy 11995 kJ/mol
8. Ionization energy 13842 kJ/mol
state of aggregation gaseously
crystal structure cubically face-centered
density (Mohshärte) 1.784 kg/m 3 volume molecular with 273 K (
- ) magnetism
not magnetically melting point 83.8 K (- 189.3 °
C ) boiling point 87.3 K (- 185.8
°C) 22,4 · 10 -3 m 3 /mol
heat of vaporization 6.447 kJ/mol
heat of fusion 1.188 kJ/mol
steam pressure -
speed of sound 308 m/s
319 m/s with 293,15 K
specific thermal capacity 520 j (kg · K)
Electrical conductivity -
heat conductivity 0.01772 w (m · K)
oxidation conditions 0
Oxides (basicity) -
Elektronegativität -
isotope NH t 1/2 ZM CPU M eV ZP
34 acre {syn.} 844.5 ms ε 6.061 34 Cl
35 acre {syn.} 1.775 s ε 5.965 35 Cl
36 acre 0.336% Acre is stable with 18 neutrons
37 acre {syn.} 35.04 D ε 0.813 37 Cl
38 acre 0.063% acre acre is stable {syn
. with 20 neutrons 39} 269 A β - 0.565 39 K
40 acre 99.6% acreacre is stable {syn
} 109.34 min β - 2.492 41 K 42 acre {syn
} 32.9 A β - 0.600 42 K 43 acre {syn
} 5.37 min β - 4.620 43 K 44 acre {syn
} 11.87 min with 22 neutrons 41 β - 3.550 44 K
as far as possible and common, are used SI-UNITs.
If not differently notes,
the indicated data apply with standard conditions.

The argon (Greek αργό (ν) [neutrally] - the slow-acting [element] - because of its chemical inertness) is in chemical element in the periodic system of the elements with the symbol acre and the ordinal number 18. Color and odorless inert gas is the most frequent noble gas in the terrestrial atmosphere.

Table of contents


were discovered argon by lord Rayleigh and Sir William Ramsay in the year 1894. The assumption of the existence of this element preceded the discovery by Henry Cavendish in the year 1785.


argon is with approximately0.933 percent by volume most frequently the noble gas occurring in the atmosphere. It is won with the fractionated distillation of liquid air ( see Luftverflüssigung).

Likewise argon results itself as by-product with the ammonia synthesis (see Haber-Bosch-processes), there it with approx.10% in the gas mixture enrich.


in water argon is nearly as well soluble as oxygen. In molten baths it is insoluble. In gas-discharge tubes argon shines violet.

As noble gas with an final Valenzschale it nearly never reactswith other elements. Only in the summer chemists Argonverbindungen under completely special conditions could manufacture 2000. A team under the line of the Finnish chemist Markku Räsänen (University of Helsinki) had succeeded in synthesizing the sturdy molecule Argonfluorohydrid (play the harp): Herefrozen argon, to which still another small quantity hydrogen fluoride was added, was illuminated with UV light.

With water argon can form Klathrate (storage connections of argon in ice).


the largest part of the world production becomes as inert gas when weldingused. It is as ionized argon laser in the eye medicine in the use. Argon is likewise used as inert gas in automatic fire-extinguishing systems. During the tungsten processing it serves as inert gas atmosphere, since tungsten already embrittles with small quantities oxygen. Argon becomes because of its smaller Wämeleitfähigkeitas air also as heat insulating filling gas assigned in insulation glass disks and Trockentauchanzügen. In addition argon is used together with nitrogen as relatively badly heat conducting poorly reactive inert gas in lamps. By the employment of argon can evaporate fewer metals of the Glühfades than in oneIt evacuated lamp whereby the life span of the lamp increase and the temperature of the filament on approximately 2500 can be increased °C by the luminous efficiency to increase.

The age determination the argon method or also potassium argon method makes themselves too uses that that usuallyfirm element potassium 40 K with a radioactive half-life from 1.3 billion years to gaseous 40 the acre disintegrates, which can escape from a melt, not however from a solid body. In the Archäometrie and in geology thereby the solidification time becomes more volcanic Materials dates.

Argon is used further in argon ions - lasers and argon krypton - lasers (Dowson gas lasers).

Further argon is used in the coating technology (to sputter/vaporizing) as feed gas, whereby it is not received reactions with the target material.

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