The Atom System is an Asset Store release that allows the user to create their own atom based on the Bohr model of atoms, inspired by the Online 3D Periodic Table by Sarath Saleem.
The script allows the user to choose the number of protons, neutrons and electrons, as well as the electron shell layout, and it can be placed anywhere in the scene while still being attracted to the local centre position of the nucleus.
If you would like the source of this project, please contact me.