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88Ra226.000
Radium
Alkaline Earth MetalRadium is a chemical element with symbol Ra and atomic number 88. It is the sixth element in group 2 of the periodic table, also known as the alkaline earth metals. Pure radium is almost colorless, but it readily combines with nitrogen (rather than oxygen) on exposure to air, forming a black surface layer of radium nitride (Ra3N2).
Phase: SolidAppearance: silvery white metallic
2, 8, 18, 32, 18, 8, 2
Physical Properties
Atomic Mass226 u
Density5.5 g/cm³
Melting Point1233 K
Boiling Point2010 K
Period7
PhaseSolid
Chemical Properties
Electron Configuration1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14 5d10 6p6 7s2
Semantic Config[Rn] 7s2
Shells2, 8, 18, 32, 18, 8, 2
Electron Affinity9.6485 kJ/mol
Electronegativity0.9
Ionization Energies
IE1: 509.3 kJ/molIE2: 979 kJ/mol
Discovery
Discovered byPierre Curie