Discovery date : 1789
Discovered by: Martin Heinrich Klaproth
Origin of the name: Uranium was named after the planet Uranus.
Allotropes :
~>URANIUM is a chemical element with symbol U and atomic number 92. It is a silvery-white metal in the actinide series of the periodic table. Uranium has the highest atomic weight of the primordially occurring elements. Its density is about 70% higher than that of lead, and slightly lower than that of gold or tungsten.
| FACT BOX | |||
| Group | Actinides | Melting point | 1135°C, 2075°F, 1408 K |
| Period | 7 | Boiling point | 4131°C, 7468°F, 4404 K |
| Block | f | Density (g cm−3) | 19.1 |
| Atomic number | 92 | Relative atomic mass | 238.029 |
| State at 20°C | Solid | Key isotopes | 234U,235U,238U |
| Electron configuration | [Rn] 5f36d17s2 | CAS number | 7440-61-1 |
| ChemSpider ID | 22425 | ChemSpider is a free chemical structure database | |
In the Middle Ages, the mineral pitchblende (uranium oxide, U3O8) sometimes turned up in silver mines, and in 1789 Martin Heinrich Klaproth of Berlin investigated it. He dissolved it in nitric acid and precipitated a yellow compound when the solution was neutralised. He realised it was the oxide of a new element and tried to produce the metal itself by heating the precipitate with charcoal, but failed.
It fell to Eugène Peligot in Paris to isolate the first sample of uranium metal which he did in 1841, by heating uranium tetrachloride with potassium.
The discovery that uranium was radioactive came only in 1896 when Henri Becquerel in Paris left a sample of uranium on top of an unexposed photographic plate. It caused this to become cloudy and he deduced that uranium was giving off invisible rays. Radioactivity had been discovered.