Radium
A glowing radioactive metal once used in luminous dials.
Inside the Radium atom
Switch between Bohr and Quantum Cloud modes to compare a simple teaching model with a more realistic probability-based view, and follow the guided tour to explore the Radium atom step by step.
Electron configuration
[Rn] 7s2
A neutral Radium atom has 88 electrons (equal to its proton count). Choosing a different isotope above changes only the neutron count.
Shell distribution
Electrons fill inner shells before outer ones; the outermost (valence) shell drives the element's chemistry.
Physical & atomic properties
- State (room temp)
- Solid
- Melting point
- 973 K (700 °C)
- Boiling point
- 2010 K (1737 °C)
- Density
- 5.5 g/cm³
- Electronegativity
- 0.9 Pauling
- Atomic radius
- 215 pm
- 1st ionization energy
- 509 kJ/mol
- Category
- Alkaline earth metals
Discovery & naming
- Discovered
- 1898
- Discovered by
- Marie and Pierre Curie
- Origin of name
- Latin 'radius', meaning ray.
Notable uses
Historic luminous paint; some cancer-therapy research.
Where Radium comes from
Neutron star mergers
Occurs on Earth only as a fleeting decay product of uranium and thorium, so it inherits their r-process origin.
Simplified origin map — many elements form through more than one astrophysical pathway.
Summary
- Atomic number
- 88
- Atomic mass
- [226]
- Category
- Alkaline earth metals
- Group · Period
- 2 · 7
- Block
- s-block
- Shells
- 2 · 8 · 18 · 32 · 18 · 8 · 2