Argon (Ar, Z = 18)
Gaz noble Bloc p Groupe 18 Période 3 Gaz (CNTP)
Argon is a chemical element with symbol Ar and atomic number 18. It is in group 18 of the periodic table and is a noble gas. Argon is the third most common gas in the Earth's atmosphere, at 0.934% (9,340 ppmv), making it over twice as abundant as the next most common atmospheric gas, water vapor (which averages about 4000 ppmv, but varies greatly), and 23 times as abundant as the next most common non-condensing atmospheric gas, carbon dioxide (400 ppmv), and more than 500 times as abundant as the next most common noble gas, neon (18 ppmv).
Découvreur : Lord Rayleigh
Propriétés physiques
- Masse atomique standard
- 39,95 u
- Densité
- 1,784 g/L
- Point de fusion
- 83,81 K
- Point d'ébullition
- 87,30 K
- Chaleur molaire
- —
- Électronégativité (Pauling)
- —
- Affinité électronique
- -96,00 kJ/mol
- Énergies d'ionisation
- 1 521 ; 2 666 ; 3 931 ; 5 771 kJ/mol
- Configuration électronique
- [Ne] 3s2 3p6
- Électrons par couche
- K : 2 · L : 8 · M : 8
- Aspect
- colorless gas exhibiting a lilac/violet glow when placed in a high voltage electric field
Correspondance ANU historique / conjectural
Comptage de la Chimie Occulte (1908) : 714 ANU (atomes ultimes), soit N/18 = 39,67 — masse « noologique » à comparer à la masse standard 39,948 u et à l'isotope dominant 40Ar. Coefficient k(Z) = 1,104
Matériel historique et conjectural — voir la page Pont ANU ↔ Nucléides.
Isotopes (26)
| Nucléide | A | N | Masse (u) | Abondance (%) | Demi-vie | Spin | Parité | Magique |
|---|---|---|---|---|---|---|---|---|
| 29Ar | 29 | 11 | 29,040761 | — | stable | 5/2 | ⁺ | — |
| 30Ar | 30 | 12 | 30,023694 | — | — | 0 | ⁺ | — |
| 31Ar | 31 | 13 | 31,012158 | — | 15 ms | 5/2 | ⁺ | — |
| 32Ar | 32 | 14 | 31,997638 | — | 98 ms | 0 | ⁺ | — |
| 33Ar | 33 | 15 | 32,989926 | — | 173 ms | 1/2 | ⁺ | — |
| 34Ar | 34 | 16 | 33,980270 | — | 846.46 ms | 0 | ⁺ | — |
| 35Ar | 35 | 17 | 34,975258 | — | 1.7756 s | 3/2 | ⁺ | — |
| 36Ar | 36 | 18 | 35,967545 | 0,3336 | stable | 0 | ⁺ | — |
| 37Ar | 37 | 19 | 36,966776 | — | 35.011 j | 3/2 | ⁺ | — |
| 38Ar | 38 | 20 | 37,962732 | 0,0629 | stable | 0 | ⁺ | N magique |
| 39Ar | 39 | 21 | 38,964313 | — | 268 an | 7/2 | ⁻ | — |
| 40Ar | 40 | 22 | 39,962383 | 99,6035 | stable | 0 | ⁺ | — |
| 41Ar | 41 | 23 | 40,964501 | — | 109.61 min | 7/2 | ⁻ | — |
| 42Ar | 42 | 24 | 41,963046 | — | 32.9 an | 0 | ⁺ | — |
| 43Ar | 43 | 25 | 42,965636 | — | 5.37 min | 5/2 | ⁻ | — |
| 44Ar | 44 | 26 | 43,964924 | — | 11.87 min | 0 | ⁺ | — |
| 45Ar | 45 | 27 | 44,968040 | — | 21.48 s | 5/2 | ⁻ | — |
| 46Ar | 46 | 28 | 45,968039 | — | 8.4 s | 0 | ⁺ | N magique |
| 47Ar | 47 | 29 | 46,972767 | — | 1.23 s | 3/2 | — | |
| 48Ar | 48 | 30 | 47,976001 | — | 415 ms | 0 | ⁺ | — |
| 49Ar | 49 | 31 | 48,981685 | — | 236 ms | 3/2 | ⁻ | — |
| 50Ar | 50 | 32 | 49,985797 | — | 106 ms | 0 | ⁺ | — |
| 51Ar | 51 | 33 | 50,993033 | — | — | 1/2 | ⁻ | — |
| 52Ar | 52 | 34 | 51,998519 | — | — | 0 | ⁺ | — |
| 53Ar | 53 | 35 | 53,007290 | — | — | 5/2 | ⁻ | — |
| 54Ar | 54 | 36 | 54,013484 | — | — | 0 | ⁺ | — |
Liseré coloré en première colonne : vert = stable, jaune = demi-vie > 1 an, orange > 1 jour, rouge < 1 jour.