Which of the following particles is not found in the nucleus of an atom?

Electrons are not found in the nucleus of an atom; they occupy regions around the nucleus called electron shells or orbitals. In contrast, the nucleus contains protons and neutrons, which are collectively referred to as nucleons. Protons have a positive charge and determine the atomic number of an element, while neutrons have no charge and contribute to the atomic mass. Understanding the structure of an atom is fundamental in radiation safety, as it helps explain how different particles interact and the nature of radioactive decay.