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500 BCE
Alchemists
Alchemists introduced the thought of breaking and creating matter. These ideas set up the inevitable creation of the periodic table. -
Period: 460 BCE to 370 BCE
Ancient Greeks
The ancient Greeks first thought of the atom, and how it is the smallest thing in the universe. They also believed that they are constantly in motion. -
John Dalton
He believed that everything was made up of atoms (indestructible). Furthermore, chemical reactions were the rearrangements of the atoms. -
Period: to
Marie Sklodowska Curie
She and Becquerel were awarded the Nobel prize for discovering radioactivity. -
J. J. Thomson
He discovered the electron and made his own model of the atom: the plum pudding model. -
Max Planck
He invented the quantum theory of energy. He also invented the Planck's constant. -
Period: to
Hantaro Nagaoka
Developed one of the earliest models of the atom. -
Period: to
Lise Meitner
Discovered uranium fission with Otto Hahn and Fritz Strassmann. -
Ernest Rutherford
He discovered the nucleus by noticing that alpha rays would scatter when aimed at the center of an atom. -
Period: to
Satyendra Nath Bose
Predicted the existence of bosons, which obeyed the quantum physics. -
Niels Bohr
He proved that electrons move in orbits around the nucleus. He also predicted that energy is released and transferred when they move from atom to atom. -
Albert Einstien
Proved that atoms could not only emit but absorb photons. -
Louis de Broglie
His theory is that all matter has the characteristics of waves and particles. -
Werner Heisenberg
Was able to take the ideas of quantum physics and formulate them. This built a foundation for being able to solve problems. -
Wolfgang Pauli
Discovered that two electrons cannot stay in the same quantum state at the same time (Pauli exclusion principle). -
Erwin Schrodinger
Was able to use mathematics to predict the position of the electron in the atom. He made his own model: the quantum mechanic model. -
James Chadwick
James changed the idea that all atoms were positively charged and he discovered neutrons. -
Period: to
Ronald J. Gillespie
He developed the Valence Shell Electron Pair Repulsion (VSEPR) theory that is commonly used. -
Period: to
Robert J. LeRoy
Was able to use quantum mechanics to study further into the diatomic spectral analysis.
