Answer by  
                                                                                          fig40 (89)
                                                            
                          
                          
                                                          The Bohr model of helium (He) is the simplest design of an atom. Helium has an atomic weight of 4 and an atomic number of two. This means that it has two protons and two neutrons and two electrons (full first shell). As a result, it is a stable representation of modern valence theory.