How is the table organized? The Periodic Table, first compiled by Russian chemist Dmitri Mendeleyev, is organized by the number of protons in the nucleus of each element's atom, known as the atomic ...

A century and a half ago, a Russian chemistry professor published a classification of all the known elements, organized by atomic weight. Today, the system that he created for his students — plus some ...

Note: This video is designed to help the teacher better understand the lesson and is NOT intended to be shown to students. It includes observations and conclusions that students are meant to make on ...