Atom
Democritus
Postulates
John Dalton
Law of Mass Conservation
Antoine Lavoisier
Law of Constant Composition
Joseph Proust
Periodic Table
Dmitri Mendeleev
Octet Rule
Gilbert N. Lewis
Father of Radioactivity
Henri Bequerel
Coined the term radioactivity
Marie Curie
Transuranium elements
Glenn Seaborg
Nuclear Fission
Enrico Fermi & Otto Han