History of the Periodic Table

Dmitri Mendeleev 1834 – 1907,

Russian

Arranged elements in order of atomic mass

Noticed patterns in chemical and physical properties

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

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