88Ra226.02541
Radium
Alkaline Earth Metal
Solid at STP
Period 7Group 2Block SDiscovered 1898
[Rn]7s2
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).
📖 Read more on Wikipedia →Atomic Properties
| Atomic Number | 88 |
| Atomic Mass | 226.02541 u |
| Electron Configuration | [Rn]7s2 |
| Oxidation States | +2 |
| Electronegativity | 0.9 (Pauling) |
| Atomic Radius | 283 pm |
| Ionization Energy | 5.279 eV |
| Block | S |
Physical Properties
| Appearance | silvery white metallic |
| Standard State | Solid |
| Melting Point | 973 K (699.9 °C) |
| Boiling Point | 1413 K (1139.8 °C) |
| Density | 5 g/cm³ |
| CPK Color | #007D00 |
Classification
| Category | Alkaline Earth Metal |
| Group Block | Alkaline earth metal |
| Period | 7 |
| Group | 2 |
| Block | S |
Discovery
| Year Discovered | 1898 |
| Discovered By | Pierre Curie |
| Electron Shells | 2, 8, 18, 32, 18, 8, 2 |