Periodic Table Dmitri Mendeleev : Periodic Table Of Elements Dmitri Mendeleev Vector Design Fototapete Fototapeten Uran Quanten Atom Myloview De : 7 horizontal rows are called periods there are 7 periods periods represent the electron. Periodic Table Dmitri Mendeleev : Periodic Table Of Elements Dmitri Mendeleev Vector Design Fototapete Fototapeten Uran Quanten Atom My... Visit Site