Uranium

Name Uranium
Symbol U
Atomic Weight 238.02891
Atomic Number 92
CAS ID 7440-61-1
Group Number
Group Name Actinoid
Period Number 7
Origin of Name Named after the planet Uranus.
Year Discovered 1789
Discovery Credits Discovered by M. H. Klaproth at Berlin, German; isolated in 1841 by E. M. Pleigot at Paris, France
Class Metallic
Color Metallic Gray
Standard State Solid at 77 F & 298 K
Description Radioactive silvery metal. malleable, ductile, and tarnishes in air. Attacked by steam and acids but not by alkalis. Used as nuclear fuel and in nuclear weapons.

Diagnostic tests: 
Uranium is usually detected by radioactivity (due, in part, to the daughter elements such as radium). Thorium is also naturally radioactive; however, many uranium minerals are generally yellow or green and fluorescent.

With a borax bead test in the oxidizing flame, the bead is yellow to brownish red color while hot and is colorless to yellow when cold. This test is very similar to iron.

The Na2(NH4)(PO4) bead  test for uranium is a much better test, under oxidizing conditions the bead is clear yellow (hot) yielding slightly greenish yellow on cooling. In the reducing flame, it becomes a fine green color when hot or cold.

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