Key discoveries that have shaped our understanding of the current atomic model include Dalton’s atomic theory, Thomson’s discovery of the electron, Rutherford’s nuclear model, Bohr’s energy levels, and Schrödinger’s quantum mechanical model.

John Dalton, an English chemist, introduced the atomic theory in the early 19th century. His theory posited that all matter is composed of tiny, indivisible particles known as atoms. Dalton’s atomic theory marked the first attempt to provide a coherent and rational explanation of the nature of matter. However, it presented a simplistic view and overlooked the complexities of the atom’s internal structure.

In 1897, J.J. Thomson made a groundbreaking discovery by identifying the electron, a negatively charged particle found in all atoms. This led to the formulation of the ‘plum pudding’ model, where the atom was envisioned as a sphere of positive charge with electrons embedded within it. This model represented a significant advancement in atomic theory as it introduced the concept of subatomic particles.

Ernest Rutherford, a physicist from New Zealand, proposed the nuclear model of the atom in 1911. He theorized that atoms consist of a small, dense, positively charged nucleus surrounded by a cloud of negatively charged electrons. This model was derived from his famous gold foil experiment, which demonstrated that most of the atom’s volume is empty space.

In 1913, Niels Bohr, a Danish physicist, introduced a model in which electrons orbit the nucleus at specific energy levels. This model provided an explanation for why atoms emit light in distinct wavelengths. However, it fell short of accurately predicting the behavior of larger atoms.

The current accepted model, developed by Erwin Schrödinger in the 1920s, is known as the quantum mechanical model. This model describes electrons as existing within a cloud-like region surrounding the nucleus, referred to as the electron cloud. It employs complex mathematical equations to predict the probability of finding an electron in a specific location around the nucleus. The quantum mechanical model offers a more accurate and comprehensive understanding of electron behavior within atoms.