| Francium [Fr] (CAS-ID: 7440-73-5) | |
| An: 87 N: 136 Am: [ 223 ] | |
| Group No: 1 Group Name: Alkali metal | |
| Block: s-block Period: 7 | |
| State: solid at 298 K | |
| Colour: Metallic Classification: Metallic | |
| Boiling Point: 950K (677'C) | |
| Melting Point: 300K (27'C) | |
| Density: 1.87g/cm3 | |
 Discovery Information |
| Who: Marguerite Perey |
| When: 1939 |
| Where: France |
| Name Origin |
| From France. |
| Sources |
| Formed by decay of actinium. Chemical properties similar to cesium. Decays to radium or astatine. |
| Uses |
| None. |
| Notes |
| The longest lived isotope, 223Fr, a daughter of 227Ac, has a half-life of 22 minutes. This is the only isotope of francium occurring in nature, but at most there is only 20-30 g of the element present in the earth's crust at any one time. No weighable quantity of the element has been prepared or isolated. There are about 20 known isotopes. |
| Images |
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This sample of uraninite contains some francium because of a steady-state decay chain. |