What element has the symbol 'Pm'?

The story behind the answer

Pm stands for Promethium, a lanthanide (atomic number 61). It’s one of only two elements below bismuth with no stable isotopes (the other is technetium), so it’s extremely rare in nature and mostly made in nuclear reactors. Named after Prometheus—the Titan who stole fire—promethium’s beta-emitting isotope Pm-147 has been used in luminous paints, thickness gauges, and small betavoltaic “nuclear batteries.”

Memory tip: Think “Pm = ProMEThium = ProMETheus,” the fire-bringer—helpful for recalling its glow-related uses. Don’t mix it up with Pd (Palladium), Pu (Plutonium), or Po (Polonium); only Promethium matches Pm.