اختبار إلكتروني: Review for the Atomic Theory and the Atom

The evolution of atomic theory provides a fascinating look into how scientists discovered the fundamental building blocks of matter. Starting with ancient philosophers like Democritus and moving into the scientific era with John Dalton, models evolved from solid spheres to J.J. Thomson’s 'plum pudding' model. Rutherford’s gold foil experiment further refined this by identifying a dense, positive nucleus, while Niels Bohr introduced planetary orbits for electrons. Today, we define atoms by their subatomic particles—protons, neutrons, and electrons—and use properties like atomic number and mass number to categorize them in the periodic table.