Uranium

Symbol

U

Atomic number

92

Atomic mass	238.029		Thermal conductivity	0.276
Atomic radius	...		Covalent radius	1.42
Density	18.7		Atomic volume	12.59
Melting point	1405		Oxidation states	6,5,4,3
Boiling point	4091		Stable isotopes	2
Heat of vapor.	477.0		Electronegativity	1.38
Heat of fusion	8.52		First ionization	6.05
Specific heat	0.12		Electrical conduct.	...

Electron configuration

Uranium

Uranium is the rarest metal of the chromium group. It was not valued until the discovery in 1942 that it was capable of nuclear fission, yielding an enormous amount of energy. For energy use, uranium is usually purified in the form of uranium oxide U3O8, commonly called yellowcake. This image of uranium oxide is from Wikipedia.

Uranium is usually found in the ores pitchblende (U₃O₈) and carnotite (K₂U₂V₂O₁₂.3H2O). It is also found in the minerals Becquerelite, euxenite and Boltwoodite. Uranium appears in the phosphate minerals meta-autunite and metatorbernite. Uranium appears with lead in curite and kasolite, both of which exhibit orange coloration which might be the source of color in radioactive orange fiestaware dishes. It appears with vanadium and lead in Francevillite.

Uranium Nuclear Data

Uranium plays a major role in the natural radioactive series on the earth. ²³⁵U is the progenitor of the uranium-235 series, ²³⁸U the progenitor of the uranium-238 series, and ²³³U is a member of the neptunium-237 series. Uranium-235 is the most important isotope for nuclear fission.

From Evans: "²³⁸U does show a half-period of about 10¹⁶ years for spontaneous fission, or about 25 fissions per hour in 1 gram of ²³⁸U. The probability of a decay is about 10⁷ times as great." The half-life for spontaneous fission for ²³⁵U is about 1.8 x 10¹⁷ years compared to its a half-life of 7 x 10⁸ years.

Uranium is a key to the uranium-lead dating processes in geology, where the ratio found in rock from the Earth, moon and meteorites is ²³⁸U/²³⁵U =137.88 (Dalrymple, Ch. 3). This ratio is use for developing the equations for Pb-Pb isochrons.