Promethium, #61

Promethium (Pm) is named for Prometheus. In the myth, the god of fire shares his knowledge with humanity. Zeus punishes him for this transgression by having him chained to a rock. An eagle eats his liver but it grows back, only to be eaten again on and on in eternal torment. Herakles (Hercules) ultimately sets Prometheus free. The gift of fire is a metaphor for all the arts and sciences that were once the exclusive province of the gods. Prometheus took a liking to people and tried to help them out, earning the wrath of his fellow deities. When wealthy, aristocratic President Franklin Delano Roosevelt tried to help poor people during the Depression, he earned the hatred of other rich people because he was a traitor to his class!

A team of Manhattan Project veterans (Jacob A. Marinsky, Lawrence E. Glendenin, and Charles D. Coryell) isolated the first sample of promethium at Oak Ridge in 1945. It was found in the decay products from the experimental graphite reactor. Their results were confirmed in 1947. The name was suggested by Coryell’s wife Grace Mary. The Promethean myth symbolizes the benefits and the perils of technology.

Element 61 was found after #60 Neodymium and #62 Samarium. The obvious gap in the Periodic Table led to predictions of the element’s existence and its properties. Several people claimed to have found what eventually become known as promethium, but the analytical techniques available at the time weren’t good enough to know for sure. The urgency of nuclear research during WWII produced a lot of improvements in the separation of isotopes. All the isotopes of promethium are radioactive. Only about half a kilogram of natural promethium is thought to exist on earth, possibly as a result of the decay of uranium minerals. Promethium is produced in the lab by bombarding U-235 with neutrons.

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