The modern version of atomic theory is generally attributed to Niels Bohr, a Danish physicist. While the concept of atoms had been proposed by the ancient Greeks, it was Bohr who, in 1913, significantly advanced the understanding of atomic structure. He built upon the earlier work of Ernest Rutherford and proposed the following key points:

* Electrons orbit the nucleus in specific energy levels (shells).

* Electrons can only jump between these energy levels by absorbing or emitting energy.

* The energy levels are quantized, meaning that electrons can only exist in specific energy states.

Bohr's model, while later superseded by more complex models, laid the foundation for our modern understanding of the atom, including how it interacts with light and other atoms.

However, it's important to note that the development of atomic theory was a collaborative effort involving numerous scientists. Some key contributions from other scientists include:

* John Dalton (1803): Proposed the first modern atomic theory, which included the idea that elements are composed of indivisible atoms.

* J.J. Thomson (1897): Discovered the electron, showing that atoms are not indivisible.

* Ernest Rutherford (1911): Proposed the nuclear model of the atom, where a positively charged nucleus is surrounded by negatively charged electrons.

While Bohr's model revolutionized our understanding of the atom, further advancements in quantum mechanics led to more sophisticated models of the atom, such as the quantum mechanical model, which is our current understanding.