Category: actinide
Atomic number: 94
Colour: silvery white
Melting point: 639°C (1,183°F)
Boiling point: 3,228°C (5,842°F)
First identified: 1940
|
Category: actinide Atomic number: 94 Colour: silvery white Melting point: 639°C (1,183°F) Boiling point: 3,228°C (5,842°F) First identified: 1940 |
Plutonium was discovered in the same year as neptunium, also at Berkeley: neptunium was synthesized and this decayed, losing a beta particle to form plutonium-239 (which in turn decays to form uranium-235). It was named after Pluto, since the previous two elements had also been named after planets.
It is quite an interesting metal – at room temperature it is brittle, but if you heat it up or alloy it with gallium, it becomes more malleable and workable. It can also be alloyed with cobalt and gallium to produce a material that is a superconductor at low temperatures (although this doesn’t last long, as the plutonium rapidly decays, damaging the material in the process). Plutonium-238 also used to be employed as a thermoelectric generator in old pacemakers. And its ability to generate heat as it decays has allowed scientists to create power sources in probes such as Cassini, which explored Saturn.
The team of scientists that synthesized what came to be known as plutonium during the A-bomb project in the Second World War was led in the US by Glenn Seaborg – apparently a guy with a quirky sense of humour. In the short term, the A-bomb project was top secret and so the codename ‘copper’ (while referring to real copper as ‘honest-to-God copper’) was used for the element. When the war ended, and Seaborg was finally allowed to rename it, he spurned the obvious choice of ‘Pl’ for the abbreviation, instead choosing ‘Pu’ – ‘he just thought it would be fun’ to name it ‘Pee-Yu’, because that is what a child might say when they encounter something really stinky. Seaborg’s joke was approved by the naming committee and is now immortalized in the periodic table.
Of course, plutonium is best known for being one of the elements used to power nuclear weapons – ‘Little Boy’ (the bomb that was used on Hiroshima) was a uranium weapon, but ‘Fat Man’ (which subsequently devastated Nagasaki) used plutonium to horrible effect.