The document summarizes key developments in the atomic theory of matter: 1) Early Greek philosophers like Democritus proposed ideas of atoms as indivisible particles that make up all matter. 2) Scientists like Lavoisier, Dalton, and Thomson contributed experimental evidence and early atomic models, including Dalton's first modern atomic theory stating atoms are indestructible particles that combine in specific ratios. 3) Rutherford's gold foil experiment provided evidence that atoms are mostly empty space with a small, dense positively charged nucleus at the center, overturning the plum pudding model.