Adapted from an image by Nobel Foundation (public domain), via Wikimedia Commons.
1907–1991
Edwin McMillan
Announced neptunium in 1940 and discovered plutonium in 1941.
Elements
93NpNeptunium
1940
In 1940 Edwin McMillan and Philip Abelson, at Berkeley, hit uranium with neutrons and found a new element among the products, the first heavier than uranium. They named it neptunium, after the planet beyond Uranus.
94PuPlutonium
1941
Glenn Seaborg, Arthur Wahl, Joseph Kennedy and Edwin McMillan made element 94 at Berkeley from uranium bombarded in the cyclotron, and proved it was new in February 1941. It was named plutonium, after the planet beyond Neptune, and kept secret until after the Second World War.
Keep exploring
Where the dates and stories on this page come from; each event on the timeline links to its own source.
- Edwin McMillanEncyclopaedia Britannica
- NeptuniumRoyal Society of Chemistry
- PlutoniumRoyal Society of Chemistry
- Edwin McMillanWikipedia