What did Niels Bohr discover about atoms?

Answer 1

It wasn't so much he "discovered" something about atoms, but that he proposed an idea about them that, while extremely radical for its time, turned out to be basically true. Specifically, that electrons surrounding the atomic nucleus are in specific orbits of a specific energy level, and that the angular momentum of the electron in each such orbit HAD to be a multiple of Planck's Constant divided by 2π (a quantity abbreviated as 'ħ'). In other words, the angular momentum of any electron in orbit around a nucleus could ħ or 2ħ or 3ħ, but it could NOT be 1.5ħ or 1.8ħ . Like many other radical ideas, some scientists liked the idea, others did not. However, when the use of the Bohr Model was successful in making predictions about helium lines, the idea was accepted, as incomplete as it was.

Answer 2

Niels Bohr proposed the planetary model of the atom, which states that electrons orbit the nucleus in specific energy levels or shells. He also introduced the concept of quantized angular momentum, which helps explain the stability of atoms and the emission of specific frequencies of light.