The number of electrons in an atom is equal to the number of protons, giving the atom a neutral charge overall. Atoms with incomplete valence shells tend to react with other atoms to complete their shells, resulting in the formation of chemical bonds. The electrons in the outermost shell, or valence shell, determine the chemical behavior of the atom. They orbit around the nucleus in shells or energy levels. ElectronĮlectrons are negatively charged particles with a mass of approximately 0.0005 amu. These different forms of the same element are called isotopes. The number of neutrons in an atom’s nucleus can vary, and atoms of the same element can have different numbers of neutrons. Like protons, they are located in the nucleus of the atom. Neutrons are neutral particles with a mass of approximately 1 amu. The number of protons in an atom’s nucleus determines its atomic number, which defines the element. They are located in the nucleus of the atom and are responsible for giving the atom its positive charge. Protons are positively charged particles with a mass of approximately 1 atomic mass unit (amu). The protons and neutrons are located in the nucleus at the center of the atom, while the electrons orbit around the nucleus in shells or energy levels. Atoms are made up of three types of subatomic particles: protons, neutrons, and electrons. The structure of an atom can be understood in terms of its constituent parts. Ernest Rutherford’s Gold Foil Experiment (1911).

Why is the atomic theory important