What is the primary atomic characteristic that Mendeleev used to organize the periodic table?
  Chemistry: Creating the Periodic Table   www.mindbites.com This lesson examines the creation of the Periodic Table of the Elements. Professor Harman walks you through the thought process involved in the grouping and the changes that led to the periodic table we are familiar with. Initially, many organization methods were tried, but Mendeleev’s method was the most successful. The Mendeleev table used two characteristics for organizations, the atomic mass and the chemical reactivity. This method better organized the elements and made it possible to accurately predict unknown elements and their physical and chemical properties. Later discoveries changed the ordering of the periodic table. Ramsay discovered Argon, which doesn’t have any chemical reactivity and whose mass fits in between two existing elements. This suggested a missing family that eventually came to be known as the Noble gases. Then, the discovery of the nucleus led to a change in ordering of atomic number (number
