Technetium is the lightest element whose isotopes are all radioactive.
Core Principles & Analysis
Technetium was the first artificially produced element, identified in 1937 by Carlo Perrier and Emilio Segre in molybdenum bombarded in Berkeley's cyclotron.
It is the lightest element with no stable isotopes, which explains the long-puzzling gap at position 43 in the periodic table.
The metastable isotope technetium-99m is the workhorse of nuclear medicine, used in tens of millions of diagnostic imaging scans each year.