<p align="right">Last Update: <font color="#4f81bd">November, 25, 2024</font></p> ## BIG IDEA - The electron is a fundamental particle; it is not composed of smaller particles. - Negatively charged [[Leptons|lepton]]. - Located in atomic orbitals (electron cloud or wave mechanics model). ### Discovery Discovered by [[J.J. Thomson]] in 1897. #### Thomson Experiment Cathode Ray Tube charged and magnetized #### Model Plum pudding model ### Size Scattering experiments provide an effective size of 2.82 femtometers (fm), or $2.82 \ x \ 10^{-15}$ meters. This is not the actual "physical size" of the electron. It is a theoretical value used to characterize its electromagnetic interactions. ### Related Topics --- [[Home|Home]] | [[Quantum mechanics]] | [[Notes Vault/Physics Notes Vault/Quantity of Motion/Quantum Mechanics/Blackbody Radiation|Blackbody Radiation]] | [[Photoelectric Effect]] | [[Atomic Theory]] | [[Atom]] | [[Early Models of the Atom]] | [[Bohr Model]] | [[Electrons]] | [[Nucleons]]