How did later discoveries change the model of mendeleev's periodic table to what we accept today? a) mendeleev's periodic table was labelled as inaccurate and his founding principles were scrapped. b) elements were arranged by atomic number and properties of the elements varied periodically with atomic number. c) while elements are arranged by atomic mass number, known families of elements are organized by electron number. d) elements were arranged by the mass number of the nucleus and properties of the elements varied periodically with mass.