Fr
Francium
العنصر 87 · 223.01973 u
Francium is the most unstable naturally occurring element with a half-life of only 22 minutes.
Physical Properties
| الكتلة الذرية | 223.01973 u |
| الكثافة | 1.87 g/cm³ |
| Melting Point | 300.0 K |
| نقطة الغليان | 950.0 K |
| المظهر | Likely silvery metallic |
| State at Room Temp | Solid |
الخواص الكيميائية
| السالبية الكهربائية | 0.7 (Pauling) |
| طاقة التأين الأولى | 380.0 kJ/mol |
| القرب الإلكتروني | 46.89 kJ/mol |
| Oxidation States | +1 |
الخصائص الذرية
| تشكيل الإلكترون | [Rn] 7s1 |
| نصف قطر الذرة | 260.0 pm |
| نصف قطر التكافؤ | 260.0 pm |
| Van der Waals Radius | 348.0 pm |
اكتشاف
| اكتشفها | Marguerite Perey |
| سنة الاكتشاف | 1939 |
| الموقع | Paris, France |
| Named After | Named after France |
عن Francium
Francium is an extremely radioactive alkali metal. Its longest-lived isotope has a half-life of only 22 minutes. It has never been produced in visible quantities and was the last element discovered in nature.
Uses & Applications
No commercial applications. Used only in basic spectroscopy research.
حقيقة مضحكة
At most about 30 grams of francium exist in the entire Earth's crust, and the largest amount collected was about 300,000 atoms.
النظائر
| Mass Number | الوفرة | نصف العمر | Stable |
| 221 | - | 4.9 minutes | No |
| 223 | - | 22.0 minutes | No |
تشكيل الإلكترون
[Rn] 7s1