-
400 BCE
Democritus
Proposed that all matter was made up of indestructible particles called atoms (atomos). -
Antoine Lavoisier
Listed 92 types of matter which we know today as "elements"; Elements in Chemistry, A New Systematic Order -
John Dalton
Said that elements consist of identical atoms and different elements combine to make compounds. Father of the Modern Atomic Theory -
Dmitri Mendeleev
Created the Periodic Table as we know it today. -
JJ Thomson
Discovered the electron and developed the plum-pudding model of the atom. Cathode ray tube experiements -
Ernest Rutherford (and others)
Demonstrated the existence of the atomic nucleus. Geiger and Marsden - Gold Foil Experiment -
Robert Millikan
Discovered the charge of an electron. Oil Drop Apparatus -
Frederick Soddy
Coined the term "isotope". -
Ernest Rutherford
Discovered the Proton. -
Niels Bohr
Proposed that the outer shell held more electrons than the inner shell. Bohr models; Nobel Prize in Physics -
James Chadwick
Discovered neutrons -
Murray Gell-Mann and George Zweig
Suggested elementary particles or 'quarks' that make up protons and neutrons. -
Large Hadron Collider
Discovered a new class of particles; pentaquarks.
