Symbol: Ra
Atomic number: 88
Category: alkaline earth metals
Group: 2
Period: 7
Block: s
Atomic weight: [226] g/mol
Electrons per shell: 2, 8, 18, 32, 18, 8, 2
CAS number: 7440-14-4
Phase: solid
Density: 5.5 kg/dm3 (near room temperature)
Melting point: 973 K (700 C, 1292 F)
Boiling point: 2010 K (1737 C, 3159 F)
Crystal structure: body centered cubic
Oxidation states: 2
Electronegativity: 0.9 (Pauling scale)
Name's origin: radius
Name's meaning: ray
- is almost pure white, but it readily oxidizes on exposure to air, turning black
- its most stable isotope, radon-226, has a half- life of 1602 years and decays into radon gas
- is luminescent (giving a faint blue color), reacts violently with water and oil to form radium hydroxide and is slightly more volatile than barium