1. History of the Periodic Table

2. Dmitri Mendeleev 1834 – 1907, Russian
Arranged elements in order of atomic mass
Noticed patterns in chemical and physical properties

3. Many periodic tables were created around the same time
Mendeleev is famous because he predicted the existence of new elements
He left blank spots in his table for the new elements

6. Henry Moseley 1887 – 1915, British
1913 – determined atomic number of elements
Rearranged periodic table according to atomic number
Went to WWI, killed at age 28