Fermium (Fm, Z = 100)
100
Fm
257,000 u
Actinide Bloc f Groupe 3 Période 7 Solide (CNTP)
Fermium is a synthetic element with symbol Fm and atomic number 100. It is a member of the actinide series. It is the heaviest element that can be formed by neutron bombardment of lighter elements, and hence the last element that can be prepared in macroscopic quantities, although pure fermium metal has not yet been prepared.
Découvreur : Lawrence Berkeley National Laboratory
Propriétés physiques
- Masse atomique standard
- 257,0 u
- Densité
- —
- Point de fusion
- 1 800,0 K
- Point d'ébullition
- —
- Chaleur molaire
- —
- Électronégativité (Pauling)
- 1,300
- Affinité électronique
- 33,96 kJ/mol
- Énergies d'ionisation
- 627 kJ/mol
- Configuration électronique
- [Rn] 5f12 7s2
- Électrons par couche
- K : 2 · L : 8 · M : 18 · N : 32 · O : 30 · P : 8 · Q : 2
Isotopes (20)
| Nucléide | A | N | Masse (u) | Abondance (%) | Demi-vie | Spin | Parité | Magique |
|---|---|---|---|---|---|---|---|---|
| 241Fm | 241 | 141 | 241,074311 | — | 730 µs | 5/2 | ⁺ | — |
| 242Fm | 242 | 142 | 242,073430 | — | 800 µs | 0 | ⁺ | — |
| 243Fm | 243 | 143 | 243,074414 | — | 231 ms | 7/2 | ⁻ | — |
| 244Fm | 244 | 144 | 244,074036 | — | 3.12 ms | 0 | ⁺ | — |
| 245Fm | 245 | 145 | 245,075354 | — | 4.2 s | 1/2 | ⁺ | — |
| 246Fm | 246 | 146 | 246,075353 | — | 1.54 s | 0 | ⁺ | — |
| 247Fm | 247 | 147 | 247,076944 | — | 31 s | 7/2 | ⁺ | — |
| 248Fm | 248 | 148 | 248,077185 | — | 34.5 s | 0 | ⁺ | — |
| 249Fm | 249 | 149 | 249,078926 | — | 1.6 min | 7/2 | ⁺ | — |
| 250Fm | 250 | 150 | 250,079520 | — | 31 min | 0 | ⁺ | — |
| 251Fm | 251 | 151 | 251,081545 | — | 5.3 h | 9/2 | ⁻ | — |
| 252Fm | 252 | 152 | 252,082466 | — | 25.39 h | 0 | ⁺ | — |
| 253Fm | 253 | 153 | 253,085181 | — | 3 j | 1/2 | ⁺ | — |
| 254Fm | 254 | 154 | 254,086852 | — | 3.24 h | 0 | ⁺ | — |
| 255Fm | 255 | 155 | 255,089963 | — | 20.07 h | 7/2 | ⁺ | — |
| 256Fm | 256 | 156 | 256,091772 | — | 157.1 min | 0 | ⁺ | — |
| 257Fm | 257 | 157 | 257,095105 | — | 100.5 j | 9/2 | ⁺ | — |
| 258Fm | 258 | 158 | 258,097077 | — | 370 µs | 0 | ⁺ | — |
| 259Fm | 259 | 159 | 259,100596 | — | 1.5 s | — | — | |
| 260Fm | 260 | 160 | 260,102809 | — | — | 0 | ⁺ | — |
Liseré coloré en première colonne : vert = stable, jaune = demi-vie > 1 an, orange > 1 jour, rouge < 1 jour.