Final answer:
The plum-pudding model proposed by Thompson described the atom as a spherical ball of positive charge with scattered electrons. Rutherford's gold foil experiment challenged this model with evidence of a dense nucleus at the center of the atom. These discoveries revolutionized chemistry by introducing the nuclear model of the atom.
Step-by-step explanation:
Plum-Pudding Model of Thompson
The plum-pudding model, proposed by J.J. Thomson in 1904, suggested that the atom was a spherical ball of positive charge, with negatively charged electrons scattered evenly throughout. The positive charges made up the pudding, while the electrons acted as isolated plums. This model could explain the overall neutrality of atoms.
Gold Foil Test of Rutherford
Rutherford's gold foil experiment, conducted in the early 1900s, aimed to test the plum-pudding model. He bombarded a thin gold foil with alpha particles and expected them to pass through un-deflected. However, he observed that a small fraction of the alpha particles were deflected at larger angles.
Revolutionizing Chemistry
Thompson's plum-pudding model laid the foundation for understanding the distribution of positive and negative charges within an atom. Rutherford's gold foil experiment revolutionized chemistry by providing evidence for the existence of a tiny, dense region at the center of the atom called the nucleus. This led to the development of the nuclear model of the atom, which introduced the concept of a positively charged nucleus surrounded by a cloud of electrons.