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500 BCE
The Alchemists
The Alchemists contributed to the atomic theory by helping to create the modern day periodic table by developing a theory that by altering the sulfur and mercury levels of a metal you can change that metal into a different metal. -
428 BCE
Plato
Plato contributed to the atomic theory by discovering a 5th atom type that makes up most planets, stars, and celestial bodies. -
400 BCE
Democritus
Democritus contributed to the atomic theory by helping to develop an initial atomic theory originated by Leucippus. -
Robert Boyle
Robert Boyle contributed to the atomic theory by coming up with a view of matter about particles and a less official theory about chemical elements. -
Antoine Lavoisier
Antoine Lavoisier contributed to the atomic theory by creating the atomic model. He did this using his findings about the relationship between total mass of products and reactants in a chemical reaction. -
The Billiard Ball Model
The Billiard Ball Model is different from the other atomic models because there are no electrons, neutrons, or protons within it. -
John Dalton
John Dalton contributed to the atomic theory by coming up with the modern day atomic theory and modern day definition of the atom. -
Amadeo Avogadro
Amadeo Avogadro contributed to the atomic theory by coming up with two hypotheses, the most important one being that elementary gases are composed of two atoms. -
Dmitri Mendeleev
Dmitri Mendeleev contributed to the atomic theory by discovering the different sections of the periodic table. -
J.J. Thompson
J.J. Thompson contributed to the atomic theory by proving the existence of electrons or negatively charged particles in an atom. -
Pierre and Marie Curie
Pierre and Marie Curie contributed to the atomic theory by discovering radioactive elements. -
The Plum Pudding Model
The Plum Pudding Model is different from every other atomic model because it had electrons mixed with positively charged protons. -
Albert Einstein
Albert Einstein contributed to the atomic theory by mathematically proving that the atom exists. -
Robert Millikan
Robert Millikan contributed to the atomic theory by discovering the electron - the easiest way to find the difference between two different elements. -
Ernest Rutherford
Ernest Rutherford contributed to the atomic theory by discovering that aside from the nucleus and electrons the atom is mostly empty space. -
Niels Bohr
Niels Bohr contributed to the atomic theory by creating a model for the most simple atom, the hydrogen atom. -
The Solar System Model
The Solar System Model is different from the other atomic models because the electrons orbit around the nucleus. -
Henry Mosely
Henry Mosely contributed to the atomic theory by discovering the atomic number or how we differentiate atoms in the periodic table. -
Erwin Schrödinger
Erwin Schrödinger contributed to the atomic theory by creating an equation to calculate the energy levels of any atom. -
The Electron Cloud Model
The Electron Cloud Model is different from the other atomic models because the nucleus is surrounded by moving electrons. -
Werner Heisenberg
Werner Heisenberg contributed to the atomic theory by discovering that a particle's position and momentum cannot exactly be known. -
James Chadwick
James Chadwick contributed to the atomic theory by discovering an important part of the atom, the neutron.