Atomic Models and Particle Scattering

This page discusses the evolution of atomic models and the groundbreaking alpha particle scattering experiment. It covers three main topics: the plum pudding model, the Rutherford nuclear model, and the alpha particle scattering experiment.

Definition: The plum pudding model was proposed by J.J. Thomson in 1897 to explain the structure of an atom.

Thomson's model suggested that the atom consisted of a positively charged "dough" with negatively charged electrons embedded within it, similar to plums in a pudding. This model was an attempt to explain the two types of static electricity observed at the time.

Highlight: The Rutherford nuclear model of an atom proposed a significant change in our understanding of atomic structure.

Ernest Rutherford's model introduced the concept of a central nucleus surrounded by orbiting electrons. In this model, electrons revolve around the nucleus at high speeds in circular paths called orbits.

Vocabulary: Alpha particle scattering experiment was a crucial experiment that led to the development of the nuclear model of the atom.

In this experiment, positively charged alpha particles were fired at a thin gold foil. The results showed that while most alpha particles passed straight through the foil, a few were scattered in different directions. This unexpected outcome provided evidence for the existence of a small, dense, positively charged nucleus at the center of the atom.

Example: The atomic structure of calcium (Ca) is shown with 20 protons in the nucleus and electrons surrounding it.

The diagram illustrates the Rutherford atomic model applied to a calcium atom, demonstrating the central nucleus and the orbiting electrons.

Quote: "The evidence from this experiment led Rutherford to suggest a new model for the atom, called the nuclear model of an atom."

This statement emphasizes the significance of the alpha particle scattering experiment in shaping our modern understanding of atomic structure.