Ra
Radium
Element 88 · 226.02541 u
Radium is a highly radioactive metal once widely used in luminous paint.
Physical Properties
| Atomic Mass | 226.02541 u |
| Density | 5.5 g/cm³ |
| Melting Point | 973.0 K |
| Boiling Point | 2010.0 K |
| Appearance | Silvery-white metallic |
| State at Room Temp | Solid |
Chemical Properties
| Electronegativity | 0.9 (Pauling) |
| 1st Ionization Energy | 509.3 kJ/mol |
| Electron Affinity | 9.65 kJ/mol |
| Oxidation States | +2 |
Atomic Properties
| Electron Configuration | [Rn] 7s2 |
| Atomic Radius | 221.0 pm |
| Covalent Radius | 221.0 pm |
| Van der Waals Radius | 283.0 pm |
Discovery
| Discovered By | Marie Curie, Pierre Curie |
| Discovery Year | 1898 |
| Location | Paris, France |
| Named After | Latin 'radius' meaning ray |
About Radium
Radium is a luminous, silvery-white radioactive metal discovered by the Curies. It glows blue due to intense radioactivity. The 'Radium Girls' who painted watch dials suffered tragic radiation poisoning.
Uses & Applications
Formerly used in luminous paint and quack medicine. Now mostly replaced in radiation therapy.
Fun Fact
The 'Radium Girls' who painted luminous watch dials suffered horrific poisoning, leading to landmark workplace safety laws.
Isotopes
| Mass Number | Abundance | Half-Life | Stable |
| 223 | - | 11.43 days | No |
| 224 | - | 3.6319 days | No |
| 226 | - | 1600 years | No |
| 228 | - | 5.75 years | No |
Electron Configuration
[Rn] 7s2