The document summarizes the development of atomic models over time. It describes Dalton's billiard ball model of atoms as indivisible, hard spheres. Thomson's plum pudding model viewed atoms as a cloud of positive charge with electrons distributed throughout. Bohr modeled atoms as a small, positively charged nucleus surrounded by electrons in circular orbits, similar to the solar system. Later models such as Rutherford's and Schrodinger's provided a more accurate quantum mechanical description of atomic structure.