- Atomic Radius (Å)
Radium 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).
88
Atomic Number
226
Atomic Mass (u)
973.15
Melting Point (K)
2010
Boiling Point (K)
5.5
Density (solid: g/cm³, gas: g/liter)
2.21
Covalent Radius (Å)
0.9
Electronegativity
5.28
First Ionization Energy (eV)
9.65
Electron Affinity
7
Number of Shells
2
Electron Valency
2, 8, 18, 32, 18, 8, 2
Electron Shell Occupations