088Alkaline earth metal · Group 2 · Period 7
Radium
Radium (Ra) is element 88, a alkaline earth metal in the s-block — group 2, period 7. It is a solid at room temperature with 7 electron shells (2, 8, 18, 32, 18, 8, 2) and an atomic mass of 226 u.
- Atomic mass
- 226.0 u
- Phase · STP
- solid
- Melting
- 1233 K · 960 °C
- Boiling
- 2010 K · 1737 °C
- Electronegativity
- 0.9
- Density
- 5.5 g/cm³
Photograph — grenadier, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons
Identity
- Atomic number
- 88
- Standard atomic weight
- 226.0 u
- Category
- Alkaline earth metal
- Group
- 2 · Alkaline earth metals
- Period
- 7
- Block
- s-block
- Oxidation states
- +2
Physical properties
- Melting point
- 1233 K · 960 °C
- Boiling point
- 2010 K · 1737 °C
- Density
- 5.5 g/cm³
- Molar heat capacity
- —
- Atomic radius
- 283 pm
- Electron affinity
- 9.6485 kJ/mol
Atomic structure
88protons
138neutrons
88electrons
2valence e⁻
- Noble-gas notation
- [Rn] 7s2
- Full configuration
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2
- Electrons per shell
- 2, 8, 18, 32, 18, 8, 2
Periodic trends
Where Radium ranks across all 118 elements.
Ionization energies
Energy to remove each successive electron (kJ/mol).
509.31
9792
Successive ionization energies (kJ/mol, log scale).
Discovery
- Discovered
- 1898
- Discovered by
- Pierre Curie
- Named by
- —
- Appearance
- silvery white metallic