Francium (Fr, Z = 87)
Métal alcalin Bloc s Groupe 1 Période 7 Solide (CNTP)
Francium is a chemical element with symbol Fr and atomic number 87. It used to be known as eka-caesium and actinium K. It is the second-least electronegative element, behind only caesium. Francium is a highly radioactive metal that decays into astatine, radium, and radon.
Découvreur : Marguerite Perey
Propriétés physiques
- Masse atomique standard
- 223,0 u
- Densité
- 1,870 g/cm³
- Point de fusion
- 300,0 K
- Point d'ébullition
- 950,0 K
- Chaleur molaire
- —
- Électronégativité (Pauling)
- 0,7900
- Affinité électronique
- 46,89 kJ/mol
- Énergies d'ionisation
- 380 kJ/mol
- Configuration électronique
- [Rn] 7s1
- Électrons par couche
- K : 2 · L : 8 · M : 18 · N : 32 · O : 18 · P : 8 · Q : 1
Correspondance ANU historique / conjectural
Comptage de la Chimie Occulte (1908) : 4 006 ANU (atomes ultimes), soit N/18 = 222,56 — masse « noologique » à comparer à la masse standard 223,000 u et à l'isotope dominant 223Fr. Coefficient k(Z) = 0,888
Matériel historique et conjectural — voir la page Pont ANU ↔ Nucléides.
Isotopes (37)
| Nucléide | A | N | Masse (u) | Abondance (%) | Demi-vie | Spin | Parité | Magique |
|---|---|---|---|---|---|---|---|---|
| 197Fr | 197 | 110 | 197,011008 | — | 2.3 ms | 7/2 | ⁻ | — |
| 198Fr | 198 | 111 | 198,010282 | — | 15 ms | 3 | ⁺ | — |
| 199Fr | 199 | 112 | 199,007269 | — | 6.6 ms | 1/2 | ⁺ | — |
| 200Fr | 200 | 113 | 200,006585 | — | 47.5 ms | 3 | ⁺ | — |
| 201Fr | 201 | 114 | 201,003852 | — | 62.8 ms | 9/2 | ⁻ | — |
| 202Fr | 202 | 115 | 202,003330 | — | 372 ms | 3 | ⁺ | — |
| 203Fr | 203 | 116 | 203,000941 | — | 550 ms | 9/2 | ⁻ | — |
| 204Fr | 204 | 117 | 204,000652 | — | 1.75 s | 3 | ⁺ | — |
| 205Fr | 205 | 118 | 204,998594 | — | 3.9 s | 9/2 | ⁻ | — |
| 206Fr | 206 | 119 | 205,998661 | — | — | 3 | ⁺ | — |
| 207Fr | 207 | 120 | 206,996941 | — | 14.8 s | 9/2 | ⁻ | — |
| 208Fr | 208 | 121 | 207,997139 | — | 59.1 s | 7 | ⁺ | — |
| 209Fr | 209 | 122 | 208,995940 | — | 50.5 s | 9/2 | ⁻ | — |
| 210Fr | 210 | 123 | 209,996411 | — | 3.18 min | 6 | ⁺ | — |
| 211Fr | 211 | 124 | 210,995555 | — | 3.1 min | 9/2 | ⁻ | — |
| 212Fr | 212 | 125 | 211,996225 | — | 20 min | 5 | ⁺ | — |
| 213Fr | 213 | 126 | 212,996184 | — | 34.14 s | 9/2 | ⁻ | N magique |
| 214Fr | 214 | 127 | 213,998971 | — | 5.51 ms | 1 | ⁻ | — |
| 215Fr | 215 | 128 | 215,000342 | — | 90 ns | 9/2 | ⁻ | — |
| 216Fr | 216 | 129 | 216,003190 | — | 700 ns | 1 | ⁻ | — |
| 217Fr | 217 | 130 | 217,004632 | — | 22 µs | 9/2 | ⁻ | — |
| 218Fr | 218 | 131 | 218,007579 | — | 1.4 ms | 1 | ⁻ | — |
| 219Fr | 219 | 132 | 219,009251 | — | 22.5 ms | 5/2 | ⁻ | — |
| 220Fr | 220 | 133 | 220,012327 | — | 27.4 s | 1 | ⁺ | — |
| 221Fr | 221 | 134 | 221,014254 | — | 4.801 min | 5/2 | ⁻ | — |
| 222Fr | 222 | 135 | 222,017583 | — | 14.2 min | 2 | ⁻ | — |
| 223Fr | 223 | 136 | 223,019734 | — | 22 min | 3/2 | — | |
| 224Fr | 224 | 137 | 224,023348 | — | 3.33 min | 1 | — | |
| 225Fr | 225 | 138 | 225,025572 | — | 3.95 min | 3/2 | ⁻ | — |
| 226Fr | 226 | 139 | 226,029545 | — | 48.5 s | 1 | — | |
| 227Fr | 227 | 140 | 227,031865 | — | 2.47 min | 1/2 | ⁺ | — |
| 228Fr | 228 | 141 | 228,035839 | — | 38 s | 2 | ⁻ | — |
| 229Fr | 229 | 142 | 229,038291 | — | 50.2 s | 1/2 | ⁺ | — |
| 230Fr | 230 | 143 | 230,042391 | — | 19.1 s | 2 | ⁺ | — |
| 231Fr | 231 | 144 | 231,045175 | — | 17.6 s | 1/2 | ⁺ | — |
| 232Fr | 232 | 145 | 232,049461 | — | 5.5 s | 5 | — | |
| 233Fr | 233 | 146 | 233,052518 | — | 900 ms | 1/2 | ⁺ | — |
Liseré coloré en première colonne : vert = stable, jaune = demi-vie > 1 an, orange > 1 jour, rouge < 1 jour.