Actinium (Ac, Z = 89)
Actinide Bloc f Groupe 3 Période 7 Solide (CNTP)
Actinium is a radioactive chemical element with symbol Ac (not to be confused with the abbreviation for an acetyl group) and atomic number 89, which was discovered in 1899. It was the first non-primordial radioactive element to be isolated. Polonium, radium and radon were observed before actinium, but they were not isolated until 1902.
Découvreur : Friedrich Oskar Giesel
Propriétés physiques
- Masse atomique standard
- 227,0 u
- Densité
- 10,00 g/cm³
- Point de fusion
- 1 500,0 K
- Point d'ébullition
- 3 500,0 K
- Chaleur molaire
- 27,20 J·mol⁻¹·K⁻¹
- Électronégativité (Pauling)
- 1,100
- Affinité électronique
- 33,77 kJ/mol
- Énergies d'ionisation
- 499 ; 1 170 kJ/mol
- Configuration électronique
- [Rn] 6d1 7s2
- Électrons par couche
- K : 2 · L : 8 · M : 18 · N : 32 · O : 18 · P : 9 · Q : 2
Correspondance ANU historique / conjectural
Comptage de la Chimie Occulte (1908) : 4 140 ANU (atomes ultimes), soit N/18 = 230,00 — masse « noologique » à comparer à la masse standard 227,000 u et à l'isotope dominant 227Ac. Coefficient k(Z) = 0,885 · multiple de 18
Matériel historique et conjectural — voir la page Pont ANU ↔ Nucléides.
Isotopes (33)
| Nucléide | A | N | Masse (u) | Abondance (%) | Demi-vie | Spin | Parité | Magique |
|---|---|---|---|---|---|---|---|---|
| 205Ac | 205 | 116 | 205,015144 | — | 80 ms | 9/2 | ⁻ | — |
| 206Ac | 206 | 117 | 206,014476 | — | 25 ms | 3 | ⁺ | — |
| 207Ac | 207 | 118 | 207,011966 | — | 31 ms | 9/2 | ⁻ | — |
| 208Ac | 208 | 119 | 208,011552 | — | 97 ms | 3 | ⁺ | — |
| 209Ac | 209 | 120 | 209,009495 | — | 94 ms | 9/2 | ⁻ | — |
| 210Ac | 210 | 121 | 210,009409 | — | 350 ms | 7 | ⁺ | — |
| 211Ac | 211 | 122 | 211,007669 | — | 213 ms | 9/2 | ⁻ | — |
| 212Ac | 212 | 123 | 212,007836 | — | 895 ms | 7 | ⁺ | — |
| 213Ac | 213 | 124 | 213,006593 | — | 738 ms | 9/2 | ⁻ | — |
| 214Ac | 214 | 125 | 214,006906 | — | 8.2 s | 5 | ⁺ | — |
| 215Ac | 215 | 126 | 215,006474 | — | 171 ms | 9/2 | ⁻ | N magique |
| 216Ac | 216 | 127 | 216,008749 | — | 440 µs | 1 | ⁻ | — |
| 217Ac | 217 | 128 | 217,009342 | — | 69 ns | 9/2 | ⁻ | — |
| 218Ac | 218 | 129 | 218,011649 | — | 1 µs | 1 | ⁻ | — |
| 219Ac | 219 | 130 | 219,012420 | — | 9.4 µs | 9/2 | ⁻ | — |
| 220Ac | 220 | 131 | 220,014755 | — | 26.36 ms | 3 | ⁻ | — |
| 221Ac | 221 | 132 | 221,015600 | — | 52 ms | 9/2 | ⁻ | — |
| 222Ac | 222 | 133 | 222,017844 | — | 5 s | 1 | ⁻ | — |
| 223Ac | 223 | 134 | 223,019136 | — | 2.1 min | 5/2 | ⁻ | — |
| 224Ac | 224 | 135 | 224,021722 | — | 2.78 h | 0 | ⁻ | — |
| 225Ac | 225 | 136 | 225,023229 | — | 9.919 j | 3/2 | ⁻ | — |
| 226Ac | 226 | 137 | 226,026097 | — | 29.37 h | 1 | ⁻ | — |
| 227Ac | 227 | 138 | 227,027751 | — | 21.772 an | 3/2 | ⁻ | — |
| 228Ac | 228 | 139 | 228,031020 | — | 6.15 h | 3 | ⁺ | — |
| 229Ac | 229 | 140 | 229,032947 | — | 62.7 min | 3/2 | ⁺ | — |
| 230Ac | 230 | 141 | 230,036327 | — | 122 s | 1 | ⁺ | — |
| 231Ac | 231 | 142 | 231,038393 | — | 7.5 min | 1/2 | ⁺ | — |
| 232Ac | 232 | 143 | 232,042034 | — | 1.98 min | 1 | ⁺ | — |
| 233Ac | 233 | 144 | 233,044346 | — | 143 s | 1/2 | ⁺ | — |
| 234Ac | 234 | 145 | 234,048139 | — | 45 s | 1 | ⁺ | — |
| 235Ac | 235 | 146 | 235,050840 | — | 62 s | 1/2 | ⁺ | — |
| 236Ac | 236 | 147 | 236,054988 | — | 4.5 min | 3 | ⁺ | — |
| 237Ac | 237 | 148 | 237,057993 | — | — | 1/2 | ⁺ | — |
Liseré coloré en première colonne : vert = stable, jaune = demi-vie > 1 an, orange > 1 jour, rouge < 1 jour.