Niels Bohr didn't *discover* where electrons can be found, but rather he proposed a model for how electrons are arranged within atoms. This model, known as the Bohr model, was revolutionary for its time. Here's what it stated:

* Electrons orbit the nucleus in specific, quantized energy levels. This means electrons can only occupy specific energy levels, not any random position.

* Each energy level has a fixed distance from the nucleus. The further an electron is from the nucleus, the higher its energy level.

* Electrons can jump between energy levels by absorbing or emitting photons of specific energies. This explains the characteristic spectral lines emitted by atoms.

While the Bohr model was a great advancement in understanding atomic structure, it has some limitations. It doesn't accurately describe the behavior of electrons in multi-electron atoms and fails to explain the finer details of atomic spectra.

Later developments, like quantum mechanics, provided a more accurate understanding of electron behavior, describing it as a wave-particle duality. This means that electrons cannot be thought of as orbiting the nucleus like planets around a sun, but rather exist in a cloud of probability called an orbital. This cloud represents the likelihood of finding an electron in a particular region of space.

So, while Bohr's model wasn't completely accurate, it laid the foundation for our current understanding of how electrons are arranged in atoms, emphasizing that they occupy specific energy levels and can transition between them.