All of the negative charge was held in the electrons, which must orbit the dense nucleus like planets around the sun. In 1912 Bohr joined Rutherford. He realized that Rutherford's model wasn't ...

When an electron dropped from a high-energy orbit to a lower-energy one, it gave out light with an energy equal to the ...

Before Bohr, atoms were seen as fragile and unstable structures. Classical electrodynamics predicted that electrons in orbit around a nucleus would radiate energy and spiral into the nucleus ...

Niels Bohr adapted Ernest Rutherford's nuclear model. Bohr did calculations that led him to suggest that electrons orbit the nucleus in shells. The shells are at certain distances from the nucleus.