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Ra
Radium
Z
88
226.0 g/mol
Alkaline Earth Metal
Radioactive
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Overview
Atomic Properties
Thermodynamics
Electromagnetism
Isotopes
88 p⁺
138 n⁰
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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]
7s
2
Semantic
Radii
r =
215
2.15
r =
221
±2
2.21
±0.02
r =
283
2.83
Empirical
215 pm
2.15 Å
Calculated
---
Covalent
221
±2
pm
2.21
±0.02
Å
van Der Waals
283 pm
2.83 Å
Oxidation States
Common
Rare
0
+2
Crystal Structure
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Body-centred Cubic
87
Fr
89
Ac
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