atomic-structure

In 1911, Ernest Rutherford interpreted Geiger and Marsden's alpha scattering data and concluded that the atom has a tiny, dense nucleus. Here is how the experiment worked and what the results proved.

How the periodic table organizes the elements: Mendeleev's predictions, atomic number, electron shells, trends, gold's color, and superheavy oganesson.

Bohr proposed electrons orbit nuclei in discrete energy levels. His model explained atomic spectroscopy and won the Nobel Prize, though quantum mechanics later refined it.