Discovery date : 1940
Discovered by: Glenn Seaborg and colleagues
Origin of the name: Plutonium, is named after the then planet Pluto,
following from the two previous elements uranium and neptunium.
Allotropes :
~>PLUTONIUM is a radioactive chemical element with symbol Pu and atomic number 94. It is an actinide metal of silvery-gray appearance that tarnishes when exposed to air, and forms a dull coating when oxidized.
| FACT BOX | |||
| Group | Actinides | Melting point | 640°C, 1184°F, 913 K |
| Period | 7 | Boiling point | 3228°C, 5842°F, 3501 K |
| Block | f | Density (g cm−3) | 19.7 |
| Atomic number | 94 | Relative atomic mass | [244] |
| State at 20°C | Solid | Key isotopes | 238Pu,239Pu,240Pu |
| Electron configuration | [Rn] 5f67s2 | CAS number | 7440-07-5 |
| ChemSpider ID | 22382 | ChemSpider is a free chemical structure database | |
Plutonium was first made in December 1940 at Berkeley, California, by Glenn Seaborg, Arthur Wahl, Joseph Kennedy, and Edwin McMillan. They produced it by bombarding uranium-238 with deuterium nuclei (alpha particles). This first produced neptunium-238 with a half-life of two days, and this decayed by beta emission to form element 94 (plutonium). Within a couple of months element 94 had been conclusively identified and its basic chemistry shown to be like that of uranium.
To begin with, the amounts of plutonium produced were invisible to the eye, but by August 1942 there was enough to see and weigh, albeit only 3 millionths of a gram. However, by 1945 the Americans had several kilograms, and enough plutonium to make three atomic bombs, one of which exploded over Nagasaki in August 1945.