90Th232.038
Thorium
Actinide
Solid at STP
Period 7Block FDiscovered 1828
[Rn]7s2 6d2
Thorium is a chemical element with symbol Th and atomic number 90. A radioactive actinide metal, thorium is one of only two significantly radioactive elements that still occur naturally in large quantities as a primordial element (the other being uranium). It was discovered in 1828 by the Norwegian Reverend and amateur mineralogist Morten Thrane Esmark and identified by the Swedish chemist Jöns Jakob Berzelius, who named it after Thor, the Norse god of thunder.
📖 Read more on Wikipedia →Atomic Properties
| Atomic Number | 90 |
| Atomic Mass | 232.038 u |
| Electron Configuration | [Rn]7s2 6d2 |
| Oxidation States | +4 |
| Electronegativity | 1.3 (Pauling) |
| Atomic Radius | 237 pm |
| Ionization Energy | 6.08 eV |
| Block | F |
Physical Properties
| Appearance | silvery, often with black tarnish |
| Standard State | Solid |
| Melting Point | 2023 K (1749.8 °C) |
| Boiling Point | 5061 K (4787.9 °C) |
| Density | 11.72 g/cm³ |
| Molar Heat | 26.23 J/(mol·K) |
| CPK Color | #00BAFF |
Classification
| Category | Actinide |
| Group Block | Actinide |
| Period | 7 |
| Block | F |
Discovery
| Year Discovered | 1828 |
| Discovered By | Jöns Jakob Berzelius |
| Electron Shells | 2, 8, 18, 32, 18, 10, 2 |