The particle that has a positive charge in an atom is called a "proton." Protons are located in the nucleus of an atom, along with neutrons, which are neutral particles. The number of protons in an atom determines its atomic number and, consequently, its identity as a specific element. For instance, an atom with one proton is hydrogen, while an atom with six protons is carbon. Protons play a crucial role in chemical reactions and influence the behavior of atoms in various physical and chemical processes.