The Periodic Table. History of Periodic Table Developed by Dmitri Mendeleev 1869 Arranged 70 known elements by increasing atomic mass Noticed a periodic.
The Periodic Table Introduction Mendeleev’s Periodic Table Dmitri Mendeleev.
What do the numbers mean? Na 11 22.990 sodium This is the atomic number. It is the number of protons in a single atom of this element. It is also #
