1937

Technetium

• The missing element with atomic number 43
• was difficult to find because only traces exist naturally on Earth.
• They named it after the Greek word meaning “artificial”
• because it was the first man-made element to be found.
• It was found in a molybdenum foil deflector
• discarded from Ernest Lawrence’s cyclotron in Berkeley.
• Lawrence mailed the radioactive foil
• to Emilio Segrè and Carlo Perrier in Palermo
• who chemically isolated a couple of isotopes,
• particularly isotopes technetium-95m and technetium-97.

Atomic number 43

• Emilio and Glenn T. Seaborg later found
• the isotope technetium-99m,
• widely used today for medical diagnostics.
• The “m” after the atomic weight signifies
• the isotope is metastable, not decaying promptly,
• but in this case with a half-life of six hours.

Unstable stuff

• Technetium decays;
• it doesn’t matter
• what isotope you have,
• it’s a sandcastle,
• a house of cards
• that tumbles, or pops.