In the early 1900s many scientists thought that an atom consisted of a positive substance with negative charges scattered throughout the substance. Then Ernest Rutherford completed an experiment that changed the concept of an atom. His discovery led to the understanding that an atom consists mostly of empty space with — electrons and protons orbiting a cloud of neutrons
electrons orbiting a dense nucleus made of protons and neutrons
neutrons and protons orbiting a cloud of electrons
protons orbiting a dense nucleus made of electrons and neutrons