Atomic Structure Nucleus-protons and neutrons Proton: 1 unit atomic mass 1 unit positive charge Neutron: 1 unit atomic mass, Neutral(no charge) 。E| ectrons Electron little mass, 1 unit negative charge 。 Atom and|on Atom: protons = of electrons lon: Atom gains/loses electron(s)Atomic Structure  Nucleus – protons and neutrons  Proton: 1 unit atomic mass,1 unit positive charge  Neutron: 1 unit atomic mass, Neutral (no charge)  Electrons  Electron: little mass, 1 unit negative charge  Atom and Ion  Atom: # protons = # of electrons  Ion: Atom gains/loses electron(s) 6