Who were they? Ernest Rutherford is a physicist who won the Nobel Prize for chemistry. He discovered the concept of radioactive half-life and theorized that atoms have their charge concentrated in a very small nucleus. Hans Geiger is a German physicist. He is a co-inventor of the Geiger counter. He is also well known for the discovering the atomic nucleus. Ernest Marsden is an undergraduate he performed the Geiger-Marsden Experiment. After serving in WWII as a Royal Engineer, he became the leading scientist in New Zealand. He founded the department of scientific and industrial research. James Chadwick is an English physicist who was awarded the Nobel Prize for discovering the neutron. He was also the head of the British scientists who worked in Manhattan.
Theories & Models Rutherford’s model of the atom was simplified in a well known symbol showing electrons circling around the nucleus, similar to the planets orbiting the Sun. Radioactivity is shown to be accomplished in which new types of matter are being continually produced.
Chadwick Theory & Model Predicted that the atom would have a neutron. He then discovered the neutron.
Validity True The nucleus is a vital part of the Rutherford-Geiger-Marsden model. The atom has a neutron. Not True In the Rutherford-Geiger-Marsden model electrons do not orbit the nucleus
Timeline Timeline Marsden Chadwick Rutherford Geiger