Uranium

Symbol: U
Atomic number: 92
Category: actinides
Group: n/a
Period: 7
Block: f
Atomic weight: 238.02891 g/mol
Electrons per shell: 2, 8, 18, 32, 21, 9, 2
CAS number: 7440-61-1
Phase: solid
Density: 19.1 kg/dm³ (near room temperature)
Melting point: 1405.3 K (1132.3 °C, 2070 °F)
Boiling point: 4404 K (4131 °C, 7468 °F)
Crystal structure: orthorhombic
Oxidation states: 3, 4, 5, 6
Electronegativity: 1.38 (Pauling scale)
Name's origin: Uranus
Name's meaning: the planet in the Solar System
Facts:
- is a silvery white, weakly radioactive metal, which is slightly softer than steel, strongly electropositive and a poor electrical conductor
- is malleable, ductile, and slightly paramagnetic
- has very high density, being approximately 70 % denser than lead, but slightly less dense than gold
- in nature, uranium atoms exist as uranium-238 (99.284%), uranium-235 (0.711%),[2] and a very small amount of uranium-234 (0.0058%)
- is used e.g. in the nuclear reactors, bombs and as a colorant in uranium glass, producing orange-red to lemon-yellow hues
- the half-life of uranium-238 is about 4.47 billion years and that of uranium-235 is 704 million years, making them useful in dating the age of the Earth
- normal functioning of the kidney, brain, liver, heart, and other systems can be affec uranium exposure, because, in addition to being weakly radioactive, uranium is a toxic metal
- finely divided uranium metal presents a fire hazard because uranium is pyrophoric; small grains will ignite spontaneously in air at room temperature