Ra
Radium
Atomic number: 88Mass: 226 uCategory: Alkaline Earth Metal
About Radium
Radium is a radioactive element discovered by Marie and Pierre Curie. It glows faintly blue in the dark due to its radioactivity causing the air around it to glow. Radium was once used in luminous watch dials, which caused cancer in the Radium Girls.
Properties
Period
7
Group
2
Block
S
Category
Alkaline Earth Metal
Electronegativity
0.90 (Pauling)
Ionization Energy
509.3 kJ/mol
Melting Point
973 K (700°C)
Boiling Point
2010 K (1737°C)
Density
5 g/cm³
Oxidation States
+2
Electron Configuration
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 4f¹⁴ 5s² 5p⁶ 5d¹⁰ 6s² 6p⁶ 7s²
[Rn] 7s²
Shell 1:2e⁻
Shell 2:8e⁻
Shell 3:18e⁻
Shell 4:32e⁻
Shell 5:18e⁻
Shell 6:8e⁻
Shell 7:2e⁻
Real-World Uses
Cancer radiotherapy (historical)
Luminous paint (historical)
Leukaemia treatment
Research
Nuclear medicine
Fun Fact
Marie Curie's notebooks are still so radioactive that they're kept in lead-lined boxes — you must sign a waiver to look at them!