What particle in an atom is responsible for the atom's positive charge?

The particle responsible for an atom's positive charge is the proton. Protons are found in the nucleus of the atom and possess a positive electrical charge. This positive charge is crucial as it balances the negative charge of the electrons, which are located in the surrounding electron cloud. The presence of protons determines the atomic number of an element, which defines what element it is and its chemical properties.

In contrast, neutrons are neutral particles found alongside protons in the nucleus and do not contribute to the charge of the atom. Electrons carry a negative charge and are not found in the nucleus but rather orbit around it. Quarks are fundamental particles that make up protons and neutrons, but they do not exist as standalone particles in an atom. Therefore, protons are the key contributors to an atom's overall positive charge, making them essential for understanding atomic structure and behavior.