This book presents the foundations of nuclear physics, covering several themes that range from subatomic particles to stars. Also described in this book are experimental facts relating to the discovery of the electron, positron, proton, neutron and neutrino. The general properties of nuclei and the various nuclear de-excitation processes based on the nucleon layer model are studied in greater depth. This book addresses the conservation laws of angular momentum and parity, the multipolar transition probabilities E and M, gamma de-excitation, internal conversion and nucleon emission de-excitation processes. The fundamental properties of α and β disintegrations, electron capture, radioactive filiations, and Bateman equations are also examined. Nuclear Physics 1 is intended for high school physics teachers, students, research teachers and science historians specializing in nuclear physics.