Argon (Ar)
noble-gasGas
Peso atomico standard
39,948 u [39,792, 39,963]Configurazione elettronica
[Ne] 3s2 3p6Punto di fusione
-189,35 °CPunto di ebollizione
-185,85 °CDensità
1,7837 kg/m³Stati di ossidazione
0Elettronegatività (Pauling)
N/DEnergia di ionizzazione (1ª)
15,759612 eVAnno della scoperta
1894Raggio atomico
71 pmDettagli
Argon is a colorless noble gas and the third most abundant gas in Earth’s atmosphere, after nitrogen and oxygen. Its closed-shell electron configuration makes it chemically very inert under ordinary conditions. Most terrestrial argon is ⁴⁰Ar, produced by the radioactive decay of ⁴⁰K in rocks. The element is valued mainly as a dense, nonreactive atmosphere for industrial, analytical, and lighting applications.
Argon is two and one half times as soluble in water as nitrogen, having about the same solubility as oxygen. Argon is colorless and odorless, both as a gas and liquid. Argon is considered to be a very inert gas and is not known to form true chemical compounds, as do krypton, xenon, and radon.
The name derives from the Greek argos for "lazy" or "inactive" because it does not combine with other elements. It was discovered in 1894 by the Scottish chemist William Ramsay and the English physicist Robert John Strutt (Lord Rayleigh) in liquefied air. Rayleigh's initial interest derived from a problem posed by the English physicist Henry Cavendish in 1785, i.e., when oxygen and nitrogen were removed from air, there was an unknown residual gas remaining.
Argon was discovered by Sir William Ramsay, a Scottish chemist, and Lord Rayleigh, an English chemist, in 1894. Argon makes up 0.93% of the earth's atmosphere, making it the third most abundant gas. Argon is obtained from the air as a byproduct of the production of oxygen and nitrogen.
From the Greek argos, inactive. Its presence in air was suspected by Cavendish in 1785, discovered by Lord Raleigh and Sir William Ramsay in 1894.
Pure argon is a monatomic gas at ordinary temperature and pressure, with no color, odor, or taste. It liquefies to a colorless liquid at cryogenic temperature and freezes to a transparent solid. In electrical discharges it emits a pale violet to lavender glow, depending on pressure and lamp conditions.
Argon is widely used as an inert shielding gas in arc welding, metal refining, and heat treatment, especially where nitrogen or oxygen would react with hot metals. It fills incandescent and some fluorescent lamps, provides inert atmospheres for crystal growth and semiconductor processing, and serves as a carrier or plasma gas in analytical instruments such as gas chromatographs and inductively coupled plasma spectrometers. Argon lasers have been used in medicine, research, and display technology, although many older uses have been replaced by other laser systems.
Argon is frequently used when an inert atmosphere is needed. It is used to fill incandescent and fluorescent light bulbs to prevent oxygen from corroding the hot filament. Argon is also used to form inert atmospheres for arc welding, growing semiconductor crystals and processes that require shielding from other atmospheric gases.
Once thought to be completely inert, argon is known to form at least one compound. The synthesis of argon fluorohydride (HArF) was reported by Leonid Khriachtchev, Mika Pettersson, Nino Runeberg, Jan Lundell and Markku Räsänen in August of 2000. Stable only at very low temperatures, argon fluorohydride begins to decompose once it warms above -246°C (-411°F). Because of this limitation, argon fluorohydride has no uses outside of basic scientific research.
It is used in electric light bulbs and in fluorescent tubes at a pressure of about 400 Pa. and in filling photo tubes, glow tubes, etc. Argon is also used as an inert gas shield for arc welding and cutting, as blanket for the production of titanium and other reactive elements, and as a protective atmosphere for growing silicon and germanium crystals.
Isotopes in Earth/Planetary Science
Argon’s chemically inert properties and three stable isotopes make it an ideal tracer of Earth processes [101] Noble Gases in Geochemistry and Cosmochemistry: Reviews in Mineralogy and Geochemistry, D. Porcelli, C. J. Ballentine, and R. Wieler (Eds.), p. 844, Mineralogical Society of America and the Geochemical Society, Washington, DC (2002)., [157] SAHRA – Sustainability of Semi-Arid Hydrology and Riparian Areas. Argon, SAHRA – Sustainability of Semi-Arid Hydrology and Riparian Areas (2014), Feb. 24; http://web.sahra.arizona.edu/programs/isotopes/argon.html., [158] J. K. W. Lee. Chem. Geol.266, 104 (2009)., [159] F. M. Phillips, M. C. Castro. “Groundwater dating and residence-time measurements”, in Treatise on Geochemistry, J. I. Drever, H. D. Holland, and K. K. Turekian (Eds.), Pergamon Press, Oxford, New York (2003)., [160] T. Kobashi, J. P. Severinghaus, K. Kawamura. Geochim. Cosmochim. Acta.72, 4675 (2008)., [161] H. Sumino, K. Ikehata, A. Shimizu, K. Nagao, S. Nakada. J. Volcanol. Geotherm. Res.175, 189 (2008)., [162] D. R. Hilton, K. Hammerschmidt, G. Loock, H. Friedrichsen. Geochim. Cosmochim. Acta.57, 2819 (1993)., [163] B. P. Christensen, P. M. Holm, A. Jambon, J. R. Wilson. Chem. Geol.178, 127 (2001)., [164] H. H. Loosli, B. E. Lehmann, W. Balderer. Geochim. Cosmochim. Acta53, 1825 (1989)., [165] T. Torgersen, B. M. Kennedy, H. Hiyagon, K. Y. Chiou, J. H. Reynolds, W. B. Clarke. Earth Planet. Sci. Lett.92, 43 (1989)., [166] J. K. Böhlke. Pure Appl. Chem.86, 1421 (2014)., [167] P. R. Renne, K. A. Farley, T. A. Becker, W. D. Sharp. Earth Planet. Sci. Lett.188, 435 (2001).. Measurements and models of the isotope-amount ratio n(40Ar)/n(36Ar) can provide insights about the evolution of the atmosphere and orogenic (mountain-building) history of the Earth. The comparison of results from potassium-argon and n(40Ar)/n(39Ar) isotope-amount-ratio dating methods with results from other dating methods has been used to study temperature histories of rocks through differences in apparent ages caused by excess argon or partial argon gas loss. The isotope-amount ratio n(40Ar)/n(36Ar) of dissolved argon in groundwater can provide hydrologic information, such as rates of crustal degassing and relative groundwater age. 38Ar produced by cosmic-ray bombardment of rocks and soils at Earth’s surface can provide information about surface exposure history and erosion rate.
Isotopes in Geochronology
Argon isotopes are used to date rock samples, especially volcanic rocks, using two related techniques (Fig. IUPAC.18.1) [101] Noble Gases in Geochemistry and Cosmochemistry: Reviews in Mineralogy and Geochemistry, D. Porcelli, C. J. Ballentine, and R. Wieler (Eds.), p. 844, Mineralogical Society of America and the Geochemical Society, Washington, DC (2002)., [168] G. B. Dalrymple, M. A. Lanphere. Potassium-Argon Dating: Principles, Techniques and Applications to Geochronology, p. 258, Freeman, San Francisco (1969)., [169] I. McDougall, T. M. Harrison. Geochronology and Thermochronology by the 40Ar/39Ar Method, p. 212, Oxford University Press, Oxford (1999)., [170] United States Geological Survey. Periodic Table-Argon, U.S. Geological Survey (2014), Feb. 25; http://wwwrcamnl.wr.usgs.gov/isoig/period/ar_iig.html..
–The first technique is potassium-argon dating (K-Ar), which is based on the decay of radioactive 40K to stable 40Ar. By comparing the concentrations of potassium and 40Ar in a sample, it is possible to determine how long the sample has been accumulating radiogenic 40Ar to determine the “age” of the sample. The half-life of 40K is approximately 1.25×109 years, making this a useful tool for dating rocks range in age from about 106 to 109 years.
–A modification of the potassium-argon dating technique is the n(40Ar)/n(39Ar) isotope-amount-ratio technique, in which a sample is irradiated in a nuclear reactor to produce 39Ar from 39K. The isotope-amount ratio n(40Ar)/n(39Ar) is then determined, and from this, the approximate age of the rock can be calculated (Fig. IUPAC.18.2).
The study of 37Ar (half-life of 35 days), 39Ar (half-life of 268 years), and 40Ar concentrations in groundwater can provide information about the production and release of these isotopes from rocks and other sources into groundwater and the relative ages of different groundwaters [159] F. M. Phillips, M. C. Castro. “Groundwater dating and residence-time measurements”, in Treatise on Geochemistry, J. I. Drever, H. D. Holland, and K. K. Turekian (Eds.), Pergamon Press, Oxford, New York (2003)., [164] H. H. Loosli, B. E. Lehmann, W. Balderer. Geochim. Cosmochim. Acta53, 1825 (1989)., [165] T. Torgersen, B. M. Kennedy, H. Hiyagon, K. Y. Chiou, J. H. Reynolds, W. B. Clarke. Earth Planet. Sci. Lett.92, 43 (1989)., [171] B. E. Lehmann, R. Purtschert. Appl. Geochem.12, 727 (1997)., [172] H. Z. Loosli, B. E. Lehmann, W. M. Smethie, Jr. “Noble gas radioisotopes: 37Ar, 85Kr, 39Ar, 81Kr”, in Environmental Tracers in Subsurface Hydrology, P. G. Cook and A. L. Herczeg (Eds.), Kluwer, Boston (2000)., [173] R. Yokochi, N. C. Sturchio, R. Purtschert. Geochim. Cosmochim. Acta88, 19 (2012)..
Isotopes in Industry
38K (half-life of 7.6 min), which is produced by the reactions 38Ar (p, n) 38K and 40Ar (n, 3n) 38K, is a widely used blood-flow tracer. Because 38Ar is more expensive, 40Ar, which also offers many additional advantages as a target, is more commonly used to produce 38K for medical purposes [176] K. Nagatsu, A. Kubodera, K. Suzuki. Appl. Radiat. Isot.49, 1505 (1998)., [177] J. R. Mercer, M. J. M. Duke, S. A. McQuarrie. Appl. Radiat. Isot.52, 1413 (2000).. 41Ar (half-life of 1.82 h) is used as an industrial gas-flow tracer to help track the movement of gases because its inert properties, half-life, and gamma radiation make it well suited for this purpose [177] J. R. Mercer, M. J. M. Duke, S. A. McQuarrie. Appl. Radiat. Isot.52, 1413 (2000)..
Argon has no stable neutral compounds under ordinary conditions, and its chemistry is extremely limited compared with heavier noble gases. The best established neutral argon compound is argon fluorohydride, HArF, made in cryogenic matrices and stable only at very low temperature. Argon can form ions and weakly bound complexes in plasmas, mass spectrometers, and solids, including ArH⁺ and van der Waals adducts. Clathrate-like trapping of argon in cages is physical inclusion rather than normal valence chemistry.
See more information at the Argon compound page.
Argon is not chemically toxic and is nonflammable, but it is an asphyxiant because it can displace breathable air, especially in confined or low-lying spaces. Liquid argon can cause severe cold burns and can embrittle some materials. Gas released from cryogenic liquid expands strongly and may create oxygen-deficient atmospheres. High-pressure cylinders add mechanical and handling hazards.
Atmospheric argon is well mixed and chemically persistent because it reacts only under exceptional conditions. Natural ⁴⁰Ar accumulates from decay of ⁴⁰K within minerals and is released slowly by weathering, volcanism, and degassing. Argon has no known biological role and is not a greenhouse gas of practical concern, since it does not absorb strongly in the main thermal infrared bands under atmospheric conditions.
Commercial argon is obtained almost entirely by fractional distillation of liquefied air, usually as a coproduct of large oxygen and nitrogen plants. Supply is therefore tied to industrial gas infrastructure and to demand for bulk oxygen in steelmaking, chemicals, and other sectors. Ultra-high-purity grades require additional purification to remove oxygen, nitrogen, water, and hydrocarbons. Recycling is uncommon for general welding use but can be economical in closed or high-purity systems such as specialized metallurgy and semiconductor processing.
The gas is prepared by fractionation of liquid air because the atmosphere contains 0.94% argon. The atmosphere of Mars contains 1.6% of 40Ar and 5 ppm of 36Ar.
Argon is a significant cosmic noble gas, produced mainly in massive stars during oxygen and silicon burning and dispersed by supernovae. In the Solar System it occurs in planetary atmospheres, meteorites, and the solar wind, but its abundance varies strongly because noble gases are readily lost from small or warm bodies. Radiogenic ⁴⁰Ar is especially important in rocky planets and in potassium-argon geochronology.
- Argon’s name comes from the Greek word for inactive, reflecting its chemical inertness.
- Atmospheric argon is mostly radiogenic ⁴⁰Ar, not primordial ³⁶Ar.
- Argon is denser than air, so leaks can accumulate in pits and poorly ventilated spaces.
- Potassium-argon dating depends on the retention of ⁴⁰Ar produced inside minerals.
- Argon is often preferred over helium when a heavier, less thermally conductive inert gas is useful.
Immagini
Proprietà
Fisiche
- Raggio atomico (empirico)
- 71 pm Confronta Raggio atomico (empirico) di tutti gli elementi →
- Raggio covalente
- 106 pm Confronta Raggio covalente di tutti gli elementi →
- Raggio di van der Waals
- 188 pm Confronta Raggio di van der Waals di tutti gli elementi →
- Densità
- 1,7837 kg/m³ Confronta Densità di tutti gli elementi →
- Volume molare
- 0,0242 L/mol
- Fase in condizioni STP
- Gas Confronta Fase in condizioni STP di tutti gli elementi →
- Punto di fusione
- -189,35 °C Confronta Punto di fusione di tutti gli elementi →
- Punto di ebollizione
- -185,85 °C Confronta Punto di ebollizione di tutti gli elementi →
- Conducibilità termica
- 0,018 W/(m·K) Confronta Conducibilità termica di tutti gli elementi →
- Capacità termica specifica
- 0,52 J/(g·K) Confronta Capacità termica specifica di tutti gli elementi →
- Capacità termica molare
- 20,786 J/(mol·K) Confronta Capacità termica molare di tutti gli elementi →
- Struttura cristallina
- Cubica a facce centrate Confronta Struttura cristallina di tutti gli elementi →
Chimiche
- Elettronegatività (Allen)
- 3,242
- Affinità elettronica
- -1 eV (valore negativo — l'atomo non dovrebbe legare un elettrone extra)
- Energia di ionizzazione (1ª)
- 15,759612 eV Confronta Energia di ionizzazione (1ª) di tutti gli elementi →
- Energia di ionizzazione (2ª)
- 27,629765 eV Confronta Energia di ionizzazione (2ª) di tutti gli elementi →
- Energia di ionizzazione (3ª)
- 40,73514 eV Confronta Energia di ionizzazione (3ª) di tutti gli elementi →
- Energia di ionizzazione (4ª)
- 59,580205 eV Confronta Energia di ionizzazione (4ª) di tutti gli elementi →
- Energia di ionizzazione (5ª)
- 74,840258 eV Confronta Energia di ionizzazione (5ª) di tutti gli elementi →
- Stati di ossidazione
- 0 Confronta Stati di ossidazione di tutti gli elementi →
- Elettroni di valenza
- 8 Confronta Elettroni di valenza di tutti gli elementi →
- Configurazione elettronica
- [Ne] 3s2 3p6
Termodinamiche
- Punto triplo (temperatura)
- -189,34 °C
- Punto triplo (pressione)
- 6,89e+4 Pa
- Punto critico (temperatura)
- -122,463 °C
- Punto critico (pressione)
- 4,863e+6 Pa
- Calore di fusione
- 0,01222988 eV Confronta Calore di fusione di tutti gli elementi →
- Calore di vaporizzazione
- 0,06664248 eV Confronta Calore di vaporizzazione di tutti gli elementi →
- Calore di atomizzazione
- 0 eV
Nucleari
- Protoni
- 18 Confronta Protoni di tutti gli elementi →
- Neutroni
- 22 Confronta Neutroni di tutti gli elementi →
- Isotopi noti
- 26 Confronta Isotopi noti di tutti gli elementi →
- Isotopi stabili
- 3 Confronta Isotopi stabili di tutti gli elementi →
- Isotopo più stabile
- Ar-40
- Anno della scoperta
- 1894
Abbondanza
- Abbondanza (crosta terrestre)
- 3,5 mg/kg Confronta Abbondanza (crosta terrestre) di tutti gli elementi →
- Abbondanza (oceano)
- 0,45 mg/L Confronta Abbondanza (oceano) di tutti gli elementi →
Struttura cristallina
- Costante reticolare a
- 526 pm
Struttura elettronica
- Elettroni per guscio
- 2, 8, 8 Confronta Elettroni per guscio di tutti gli elementi →
Identificativi
- Numero CAS
- 7440-37-1 Confronta Numero CAS di tutti gli elementi →
- Simbolo di termine
- 1S0
- InChI
- InChI=1S/Ar
- Chiave InChI
- XKRFYHLGVUSROY-UHFFFAOYSA-N
Configurazione elettronica Misurato
Ar: 3s² 3p⁶[Ne] 3s² 3p⁶1s² 2s² 2p⁶ 3s² 3p⁶Modello atomico
Gli isotopi modificano il numero di neutroni, la massa e la stabilità — non la configurazione elettronica di un atomo neutro.
Modello atomico schematico, non in scala.
Impronta atomica
Spettro di emissione / assorbimento
Distribuzione isotopica
| Numero di massa | Massa atomica (u) | Abbondanza naturale | Emivita |
|---|---|---|---|
| 36 Stabile | 35,967545105 ± 0,000000028 | 0,3336% | Stabile |
| 38 Stabile | 37,96273211 ± 0,00000021 | 0,0629% | Stabile |
| 40 Stabile | 39,9623831237 ± 0,0000000024 | 99,6035% | Stabile |
Fase / Stato
Motivo: 210,8 °C sopra il punto di ebollizione (-185,85 °C)
Schema non in scala
Punti di transizione di fase
Energie di transizione
Energia necessaria per fondere 1 mol al punto di fusione
Energia necessaria per vaporizzare 1 mol al punto di ebollizione
Densità
In condizioni standard
Stimata con la legge dei gas ideali alla T attuale
Avanzate
Spettri atomici
Sono visualizzati 10 di 18. Ordinamento per carica ionica crescente.
Righe disponibili ?
| Ione | Carica | Righe totali | Probabilità di transizione | Designazioni dei livelli |
|---|---|---|---|---|
| Ar I | 0 | 461 | 428 | 429 |
| Ar II | +1 | 2858 | 307 | 2858 |
| Ar III | +2 | 509 | 80 | 509 |
| Ar IV | +3 | 256 | 42 | 256 |
| Ar V | +4 | 111 | 18 | 111 |
| Ar VI | +5 | 104 | 6 | 104 |
| Ar VII | +6 | 218 | 21 | 218 |
| Ar VIII | +7 | 141 | 27 | 141 |
| Ar IX | +8 | 178 | 2 | 178 |
| Ar X | +9 | 92 | 1 | 92 |
Livelli disponibili ?
| Ione | Carica | Livelli |
|---|---|---|
| Ar I | 0 | 504 |
| Ar II | +1 | 419 |
| Ar III | +2 | 125 |
| Ar IV | +3 | 58 |
| Ar V | +4 | 49 |
| Ar VI | +5 | 44 |
| Ar VII | +6 | 95 |
| Ar VIII | +7 | 72 |
| Ar IX | +8 | 98 |
| Ar X | +9 | 71 |
Composti
Isotopi (3)
Naturally occurring argon is a mixture of three isotopes. Twelve other radioactive isotopes are known to exist.
| Numero di massa | Massa atomica (u) | Abbondanza naturale | Emivita | Modalità di decadimento | |
|---|---|---|---|---|---|
| 36 Stabile | 35,967545105 ± 0,000000028 | 0,3336% ± 0,0021% | Stabile | stable | |
| 38 Stabile | 37,96273211 ± 0,00000021 | 0,0629% ± 0,0007% | Stabile | stable | |
| 40 Stabile | 39,9623831237 ± 0,0000000024 | 99,6035% ± 0,0025% | Stabile | stable |
Righe spettrali
Sono visualizzati 50 di 1065. Per impostazione predefinita sono mostrate soltanto le righe spettrali con intensità misurata.
| Lunghezza d'onda (nm) | Intensità | Stadio di ionizzazione | Tipo | Transizione | Accuratezza | Fonte | |
|---|---|---|---|---|---|---|---|
| 458.989759 nm | 25704 | Ar II | emission | 3s2.3p4.(1D).4s 2D → 3s2.3p4.(1D).4p 2F* | Misurata | NIST | |
| 472.686807 nm | 23442 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2D* | Misurata | NIST | |
| 696.543 nm | 10000 | Ar I | emission | 3s2.3p5.(2P*<3/2>).4s 2[3/2]* → 3s2.3p5.(2P*<1/2>).4p 2[1/2] | Misurata | NIST | |
| 706.72175 nm | 10000 | Ar I | emission | 3s2.3p5.(2P*<3/2>).4s 2[3/2]* → 3s2.3p5.(2P*<1/2>).4p 2[3/2] | Misurata | NIST | |
| 738.39801 nm | 10000 | Ar I | emission | 3s2.3p5.(2P*<3/2>).4s 2[3/2]* → 3s2.3p5.(2P*<1/2>).4p 2[3/2] | Misurata | NIST | |
| 440.098598 nm | 8710 | Ar II | emission | 3s2.3p4.(3P).3d 4D → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 501.716264 nm | 7413 | Ar II | emission | 3s2.3p4.(3P).3d 2D → 3s2.3p4.(1D).4p 2F* | Misurata | NIST | |
| 476.486444 nm | 2344 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2P* | Misurata | NIST | |
| 460.956692 nm | 2291 | Ar II | emission | 3s2.3p4.(1D).4s 2D → 3s2.3p4.(1D).4p 2F* | Misurata | NIST | |
| 487.986345 nm | 2239 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2D* | Misurata | NIST | |
| 727.29354 nm | 2000 | Ar I | emission | 3s2.3p5.(2P*<3/2>).4s 2[3/2]* → 3s2.3p5.(2P*<1/2>).4p 2[1/2] | Misurata | NIST | |
| 427.752786 nm | 1995 | Ar II | emission | 3s2.3p4.(1D).4s 2D → 3s2.3p4.(1D).4p 2P* | Misurata | NIST | |
| 434.806354 nm | 1995 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4D* | Misurata | NIST | |
| 480.602014 nm | 1820 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 454.505166 nm | 1738 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2P* | Misurata | NIST | |
| 442.60008 nm | 1514 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4D* | Misurata | NIST | |
| 465.79009 nm | 1445 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2P* | Misurata | NIST | |
| 473.590548 nm | 1000 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 714.7041 nm | 1000 | Ar I | emission | 3s2.3p5.(2P*<3/2>).4s 2[3/2]* → 3s2.3p5.(2P*<1/2>).4p 2[3/2] | Misurata | NIST | |
| 413.172327 nm | 891 | Ar II | emission | 3s2.3p4.(1D).4s 2D → 3s2.3p4.(1D).4p 2P* | Misurata | NIST | |
| 496.507942 nm | 891 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2D* | Misurata | NIST | |
| 457.934934 nm | 871 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2S* | Misurata | NIST | |
| 484.780955 nm | 832 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 437.988058 nm | 794 | Ar II | emission | 3s2.3p4.(3P).4p 2S* → 3s2.3p4.(3P).5s 2P | Misurata | NIST | |
| 407.200431 nm | 708 | Ar II | emission | 3s2.3p4.(1D).4s 2D → 3s2.3p4.(1D).4p 2D* | Misurata | NIST | |
| 443.018862 nm | 661 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4D* | Misurata | NIST | |
| 448.181045 nm | 646 | Ar II | emission | 3s2.3p4.(3P).3d 2D → 3s2.3p4.(1D).4p 2D* | Misurata | NIST | |
| 437.075295 nm | 617 | Ar II | emission | 3s2.3p4.(3P).3d 2D → 3s2.3p4.(1D).4p 2D* | Misurata | NIST | |
| 433.119915 nm | 603 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4D* | Misurata | NIST | |
| 437.966649 nm | 550 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4D* | Misurata | NIST | |
| 611.492319 nm | 537 | Ar II | emission | 3s2.3p4.(1D).3d 2G → 3s2.3p4.(1D).4p 2F* | Misurata | NIST | |
| 410.391181 nm | 447 | Ar II | emission | 3s2.3p4.(3P).4p 4D* → 3s2.3p4.(3P).5s 4P | Misurata | NIST | |
| 617.227751 nm | 407 | Ar II | emission | 3s2.3p4.(1D).3d 2G → 3s2.3p4.(1D).4p 2F* | Misurata | NIST | |
| 415.85907 nm | 400 | Ar I | emission | 3s2.3p5.(2P*<3/2>).4s 2[3/2]* → 3s2.3p5.(2P*<3/2>).5p 2[3/2] | Misurata | NIST | |
| 420.067472 nm | 400 | Ar I | emission | 3s2.3p5.(2P*<3/2>).4s 2[3/2]* → 3s2.3p5.(2P*<3/2>).5p 2[5/2] | Misurata | NIST | |
| 506.203703 nm | 398 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 437.132854 nm | 355 | Ar II | emission | 3s2.3p4.(3P).3d 4D → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 500.93342 nm | 355 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 447.475916 nm | 347 | Ar II | emission | 3s2.3p4.(3P).3d 2D → 3s2.3p4.(1D).4p 2P* | Misurata | NIST | |
| 422.815775 nm | 331 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 2D* | Misurata | NIST | |
| 404.289342 nm | 288 | Ar II | emission | 3s2.3p4.(1D).4s 2D → 3s2.3p4.(1D).4p 2D* | Misurata | NIST | |
| 426.652661 nm | 288 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4D* | Misurata | NIST | |
| 488.904194 nm | 288 | Ar II | emission | 3s2.3p4.(3P).4s 2P → 3s2.3p4.(3P).4p 2P* | Misurata | NIST | |
| 423.721956 nm | 269 | Ar II | emission | 3s2.3p4.(1D).4s 2D → 3s2.3p4.(1D).4p 2P* | Misurata | NIST | |
| 664.369734 nm | 269 | Ar II | emission | 3s2.3p4.(3P).3d 4F → 3s2.3p4.(3P).4p 4D* | Misurata | NIST | |
| 385.058079 nm | 263 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4S* | Misurata | NIST | |
| 440.009637 nm | 257 | Ar II | emission | 3s2.3p4.(3P).3d 4D → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 443.099589 nm | 251 | Ar II | emission | 3s2.3p4.(3P).3d 4D → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 493.320891 nm | 251 | Ar II | emission | 3s2.3p4.(3P).4s 4P → 3s2.3p4.(3P).4p 4P* | Misurata | NIST | |
| 514.17826 nm | 224 | Ar II | emission | 3s2.3p4.(3P).3d 2D → 3s2.3p4.(1D).4p 2F* | Misurata | NIST |
Proprietà estese
Raggi covalenti (dati estesi)
- Raggio covalente (Pyykkö)
- 96 pm
- Raggio covalente (Pyykkö, legame doppio)
- 107 pm
- Raggio covalente (Pyykkö, legame triplo)
- 96 pm
Raggi di van der Waals
- Bondi
- 188 pm
- Alvarez
- 194 pm
- UFF
- 386,8 pm
- MM3
- 199 pm
Raggi atomici e metallici
- Raggio atomico (Rahm)
- 197 pm
Scale di numerazione
- Mendeleev
- 114
- Pettifor
- 3
- Glawe
- 3
Scale di elettronegatività
- Ghosh
- 0
- Gunnarsson–Lundqvist
- 5
- Robles–Bartolotti
- 5
Polarizzabilità e dispersione
- Polarizzabilità dipolare
- 11,083 a.u.
- Polarizzabilità dipolare (inc.)
- 0,007 a.u.
- C₆
- 64,2 Ha·Bohr6
- C₆ (Gould–Bučko)
- 67,4 Ha·Bohr6
Affinità chimica
- Affinità protonica
- 369,2 kJ/mol
- Basicità in fase gassosa
- 346,3 kJ/mol
Proprietà dei gas nobili
Transizioni di fase e allotropi
| Punto di fusione | 83,81 K |
| Punto di ebollizione | 87,3 K |
| Punto critico (temperatura) | 150,69 K |
| Punto critico (pressione) | 4,86 MPa |
| Punto triplo (temperatura) | 83,81 K |
| Punto triplo (pressione) | 68,89 kPa |
Dati di riferimento avanzati
Costanti di schermaggio (5)
| n | Orbitale | σ |
|---|---|---|
| 1 | s | 0,4925 |
| 2 | p | 3,9918 |
| 2 | s | 5,7696 |
| 3 | p | 11,2359 |
| 3 | s | 10,2432 |
Modalità di decadimento degli isotopi (46)
| Isotopo | Modalità | Intensità |
|---|---|---|
| 29 | 2p | 100% |
| 30 | 2p | 100% |
| 31 | B+ | 100% |
| 31 | B+p | 68,3% |
| 31 | 2p | 9% |
| 31 | B+pA | 0,4% |
| 31 | 3p | 0,1% |
| 31 | B+A | 0% |
| 31 | 2p | 0% |
| 32 | B+ | 100% |
Fattori di diffusione dei raggi X (506)
| Energia (eV) | f₁ | f₂ |
|---|---|---|
| 10 | — | 0 |
| 10,1617 | — | 0 |
| 10,3261 | — | 0 |
| 10,4931 | — | 0 |
| 10,6628 | — | 0 |
| 10,8353 | — | 0 |
| 11,0106 | — | 0 |
| 11,1886 | — | 0 |
| 11,3696 | — | 0 |
| 11,5535 | — | 0 |
Dati aggiuntivi
Estimated Crustal Abundance
The estimated element abundance in the earth's crust.
3.5 milligrams per kilogram
Riferimenti (1)
Estimated Oceanic Abundance
The estimated element abundance in the earth's oceans.
4.5×10-1 milligrams per liter
Riferimenti (1)
Sources
Sources of this element.
The gas is prepared by fractionation of liquid air because the atmosphere contains 0.94% argon. The atmosphere of Mars contains 1.6% of 40Ar and 5 ppm of 36Ar.
Riferimenti (1)
- [6] Argon https://periodic.lanl.gov/18.shtml
Riferimenti
(9)
Data deposited in or computed by PubChem
The half-life and atomic mass data was provided by the Atomic Mass Data Center at the International Atomic Energy Agency.
Element data are cited from the Atomic weights of the elements (an IUPAC Technical Report). The IUPAC periodic table of elements can be found at https://iupac.org/what-we-do/periodic-table-of-elements/. Additional information can be found within IUPAC publication doi:10.1515/pac-2015-0703 Copyright © 2020 International Union of Pure and Applied Chemistry.
The information are cited from Pure Appl. Chem. 2018; 90(12): 1833-2092, https://doi.org/10.1515/pac-2015-0703.
Thomas Jefferson National Accelerator Facility (Jefferson Lab) is one of 17 national laboratories funded by the U.S. Department of Energy. The lab's primary mission is to conduct basic research of the atom's nucleus using the lab's unique particle accelerator, known as the Continuous Electron Beam Accelerator Facility (CEBAF). For more information visit https://www.jlab.org/
The periodic table at the LANL (Los Alamos National Laboratory) contains basic element information together with the history, source, properties, use, handling and more. The provenance data may be found from the link under the source name.
The periodic table contains NIST's critically-evaluated data on atomic properties of the elements. The provenance data that include data for atomic spectroscopy, X-ray and gamma ray, radiation dosimetry, nuclear physics, and condensed matter physics may be found from the link under the source name. Ref: https://www.nist.gov/pml/atomic-spectra-database
This section provides all form of data related to element Argon.
The element property data was retrieved from publications.