10 a.m.u. 1 a.m.u. 1/1800 a.m.u. 1/2 a.m.u.
Neutron Proton Neither Electron
Lithium Hydrogen Beryllium Helium
Totally randomly 1 circular orbit In random energy levels In discrete energy levels
Neutrons Neither Protons Electrons
Compound Mole Particle Isotope