Ra
Radium
Z 88 226.0 g/molAlkaline Earth Metal Radioactive
Nucleus
88 Protons
138 Neutrons
88 Electrons (2 Valence)
Shell distribution: K2 • L8 • M18 • N32 • O18 • P8 • Q2
Electron Configuration
Energy
7p
6d
5f
7s
6p
5d
4f
6s
5p
4d
5s
4p
3d
4s
3p
3s
2p
2s
1s
[Rn]7s2
Oxidation States
CommonRare
0
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Radii
Empirical
215 pm2.15 Å
Calculated
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Covalent
221±2 pm2.21±0.02 Å
Van der Waals
283 pm2.83 Å
IonicRa2+ · CN 8
148 pm1.48 Å
Crystal Structure
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Body-centered cubic
Pearson symbol
cI2
Space group
Im3m No. 229