Magnésium (Mg, Z = 12)
Métal alcalino-terreux Bloc s Groupe 2 Période 3 Solide (CNTP)
Magnesium is a chemical element with symbol Mg and atomic number 12. It is a shiny gray solid which bears a close physical resemblance to the other five elements in the second column (Group 2, or alkaline earth metals) of the periodic table:they each have the same electron configuration in their outer electron shell producing a similar crystal structure. Magnesium is the ninth most abundant element in the universe.
Découvreur : Joseph Black
Propriétés physiques
- Masse atomique standard
- 24,31 u
- Densité
- 1,738 g/cm³
- Point de fusion
- 923,0 K
- Point d'ébullition
- 1 363,0 K
- Chaleur molaire
- 24,87 J·mol⁻¹·K⁻¹
- Électronégativité (Pauling)
- 1,310
- Affinité électronique
- -40,00 kJ/mol
- Énergies d'ionisation
- 738 ; 1 451 ; 7 733 ; 10 543 kJ/mol
- Configuration électronique
- [Ne] 3s2
- Électrons par couche
- K : 2 · L : 8 · M : 2
- Aspect
- shiny grey solid
Correspondance ANU historique / conjectural
Comptage de la Chimie Occulte (1908) : 432 ANU (atomes ultimes), soit N/18 = 24,00 — masse « noologique » à comparer à la masse standard 24,305 u et à l'isotope dominant 24Mg. Coefficient k(Z) = 1,160 · multiple de 18
Matériel historique et conjectural — voir la page Pont ANU ↔ Nucléides.
Isotopes (23)
| Nucléide | A | N | Masse (u) | Abondance (%) | Demi-vie | Spin | Parité | Magique |
|---|---|---|---|---|---|---|---|---|
| 19Mg | 19 | 7 | 19,034180 | — | 5 ps | 1/2 | ⁻ | — |
| 20Mg | 20 | 8 | 20,018763 | — | 90.4 ms | 0 | ⁺ | N magique |
| 21Mg | 21 | 9 | 21,011706 | — | 120 ms | 5/2 | ⁺ | — |
| 22Mg | 22 | 10 | 21,999571 | — | 3.8745 s | 0 | ⁺ | — |
| 23Mg | 23 | 11 | 22,994124 | — | 11.3039 s | 3/2 | ⁺ | — |
| 24Mg | 24 | 12 | 23,985042 | 78,9650 | stable | 0 | ⁺ | — |
| 25Mg | 25 | 13 | 24,985837 | 10,0110 | stable | 5/2 | ⁺ | — |
| 26Mg | 26 | 14 | 25,982593 | 11,0250 | stable | 0 | ⁺ | — |
| 27Mg | 27 | 15 | 26,984341 | — | 9.435 min | 1/2 | ⁺ | — |
| 28Mg | 28 | 16 | 27,983875 | — | 20.915 h | 0 | ⁺ | — |
| 29Mg | 29 | 17 | 28,988607 | — | 1.3 s | 3/2 | ⁺ | — |
| 30Mg | 30 | 18 | 29,990465 | — | 317 ms | 0 | ⁺ | — |
| 31Mg | 31 | 19 | 30,996648 | — | 270 ms | 1/2 | ⁺ | — |
| 32Mg | 32 | 20 | 31,999110 | — | 80.4 ms | 0 | ⁺ | N magique |
| 33Mg | 33 | 21 | 33,005328 | — | 92 ms | 3/2 | ⁻ | — |
| 34Mg | 34 | 22 | 34,008935 | — | 44.9 ms | 0 | ⁺ | — |
| 35Mg | 35 | 23 | 35,016790 | — | 11.3 ms | 3/2 | ⁻ | — |
| 36Mg | 36 | 24 | 36,021879 | — | 3.9 ms | 0 | ⁺ | — |
| 37Mg | 37 | 25 | 37,030286 | — | 8 ms | 3/2 | ⁻ | — |
| 38Mg | 38 | 26 | 38,036580 | — | — | 0 | ⁺ | — |
| 39Mg | 39 | 27 | 39,045921 | — | stable | 7/2 | ⁻ | — |
| 40Mg | 40 | 28 | 40,053194 | — | — | 0 | ⁺ | N magique |
| 41Mg | 41 | 29 | 41,062373 | — | stable | 3/2 | ⁻ | — |
Liseré coloré en première colonne : vert = stable, jaune = demi-vie > 1 an, orange > 1 jour, rouge < 1 jour.