Details : Item 215
| 1 | 2 | 3 | 4 | 5 | 6 | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Alkali metals |  |  |  |  |  |  | |||||
| Alkaline earth metal |  |  |  |  |  |  | |||||
| Transition metals I |  |  |  |  |  |  | |||||
| Transition metals II |  |  |  |  |  |  | |||||
| Transition metals III |  |  |  |  |  |  | |||||
| Transition metals IV |  |  |  |  |  |  | |||||
| Post-transition metal |  |  |  |  | | | |||||
| Metalloid | | | | | | | |||||
| Diatomic non-metal | | | | | | | |||||
| Noble gas | | | | | | | |||||
| Other | | | | | | | |||||
 | |||||||||||
| Famille : Alkali metals/6 |
|---|
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| Francium |
| Symbol: Fr, phase: solid presumably Bulk francium has never been viewed. As little as 20–30 g exists at any given time throughout the Earth s crust. The largest amount produced was a cluster of 300,000 atoms. |
| Properties | |
|---|---|
| Atomic number | 87 |
| Atomic weight | 223 |
| Melting point (K) | 300 |
| Boiling point (K) | 950 |
| Speed of sound (m/s) | N/A |
| Discovery | 1939 (M. Perey) |