Bismuth is a pentavalent post-transition metal and one of the pnictogens, noted for its iridescent oxide tarnish.
Core Principles & Analysis
Bismuth was used by medieval metalworkers but was only proven distinct from lead by Claude Francois Geoffroy in 1753.
It is the most diamagnetic element, expands about 3 percent on freezing, and its one natural isotope decays so slowly its half-life is a billion times the age of the universe.
Bismuth subsalicylate settles upset stomachs as Pepto-Bismol, and low-melting bismuth alloys trigger fire-sprinkler heads and replace lead in shot and solder.