The video discusses the foundational experiments that led to the modern atomic theory, focusing on the contributions of JJ Thompson, Millikan, and Rutherford. Thompson's cathode ray tube experiment identified the electron, Millikan's oil drop experiment measured the electron's charge and mass, and Rutherford's gold foil experiment revealed the atomic nucleus.

This chapter introduces atomic theory and atomic structure, focusing on early experiments that shaped our understanding of the atom. It highlights JJ Thompson's cathode ray tube experiment, which led to the discovery of the electron and its properties.

Millikan's oil drop experiment demonstrated the balance of gravitational and electric forces on charged oil droplets, allowing the determination of the electron's mass and charge. By using an atomizer to create uniform oil droplets and x-rays to impart a negative charge, Millikan was able to measure these fundamental properties accurately.

Rutherford's gold foil experiment revealed that atoms have a tiny, dense nucleus containing most of the atom's mass, surrounded by much lighter, diffuse electrons. By shooting alpha particles at gold foil, he observed that most particles passed through, but some deflected, indicating the presence of a massive nucleus.