Italian-American physicist · 1905–1989
Emilio Segrè
Emilio Segrè found the first element ever made by people. Technetium, identified in 1937, filled a gap the periodic table had held open for 70 years. He went on to discover astatine and later won a Nobel Prize for discovering the antiproton.
- Elements credited
- 2
- Discoveries
- 1937–1940
- Co-discoverers
- 3
- Where
- Italy; United States
The work
In 1937 Segrè visited Ernest Lawrence’s cyclotron at Berkeley and took home a molybdenum strip that had been bombarded with deuterons. In Palermo he and the mineralogist Carlo Perrier dissolved it and chemically isolated a radioactive substance that behaved like manganese and rhenium. It was element 43, which had never been found in nature. They named it technetium, from the Greek for “artificial”.
In 1940, having moved to Berkeley, he joined Dale Corson and Kenneth MacKenzie in bombarding bismuth with alpha particles. The product was element 85, the heaviest halogen, which they named astatine, “unstable”.
Technetium and Astatine side by side
| Property | Technetium | Astatine |
|---|---|---|
| Discovered | 1937 | 1940 |
| Atomic number | 43 | 85 |
| Category | Transition metal | Halogen |
| State at room temperature | Solid | Solid |
| Melting point | 2,157 °C | 302 °C |
| Density | 11 g/cm³ | 7 g/cm³ |
Life and career
Segrè was born in Tivoli near Rome and studied under Enrico Fermi, joining the group of young physicists who studied slow neutrons in Rome. He became professor in Palermo in 1936.
In 1938, while he was visiting Berkeley, Mussolini’s racial laws barred Jews from Italian universities, and he stayed in the United States. He worked on the Manhattan Project at Los Alamos and later shared the 1959 Nobel Prize in Physics with Owen Chamberlain for discovering the antiproton.
Also known for
- 1959 Nobel Prize in Physics for the antiproton
- Helped show in 1941 that plutonium-239 splits with slow neutrons