The Bohr model, introduced by Danish physicist Niels Bohr in 1913, was a key step on the journey to understand atoms. Ancient Greek thinkers already believed that matter was composed of tiny basic ...

For millennia, atoms had been phantoms, widely suspected to exist but remaining stubbornly invisible — though not indivisible, as their name (Greek for “uncuttable”) originally implied. By the start ...

John L. Heilbron describes the route that led Niels Bohr to quantize electron orbits a century ago. You have full access to this article via your institution ...