Which chemical element has the lowest boiling point?

The story behind the answer

Helium has the lowest boiling point of any element (about 4.2 K, −269 °C) because its atoms barely attract each other. As the smallest, least polarizable noble gas and a monatomic species, helium experiences the weakest London dispersion (van der Waals) forces, so very little heat is needed to separate its atoms into a gas. Quantum effects also matter: helium’s large zero-point energy keeps it from condensing or freezing easily.

That extreme cold behavior has big uses—liquid helium cools superconducting magnets in MRI machines and research labs, and helium-4 becomes a frictionless “superfluid” below 2.17 K. Memory tip: Helium “won’t hang on,” so it “boils away first”—think of a party balloon that slips from your hand and disappears skyward.