-
500 BCE
The Alchemists
The alchemists said that all metals were formed from two elements mercury and sulfur. -
460 BCE
Democritus
Said all matter is made up of small units called atoms. Moved in infinite numbers till time stopped -
427 BCE
Plato
Plato was the first person to come up with the atomic theory -
350 BCE
Aristotle
matter was fundamentally constructed out of atoms -
Lavoisier
said that matter was not created or destroyed in chemical reactions -
Dalton
all matter is made of atoms and all atoms of an element are identical in mass -
Newland's law of octaves
chemical elements that are arranged by atomic weight occur after seven elements -
Mendeleev's Pd. Table
elements were related to their mass in a periodic way. -
Einstein
Einstein was a theoretical physicist born in Germany, he is one of the most important and influential Physicists of all time and made many important contributions. said that any liquid is made up of atoms. -
Photoelectric Effect
electrically charged released from a material when the material absorbs electromagnetic radiation. -
Discovery of Radioactivity
On a overcast day in 1896 Henri Becquerel opened a drawer and discovery spontaneous radioactivity on accident. -
Discovery of the electron
Used cathode rays to find the carrier of electrical properties -
Planck's quantum theory of light
atoms and molecules can emit or absorb energy in discrete quantities only. -
Plum Pudding model
negatively charged particles in a pack of positive charge -
Rutherford's Gold Foil Experiment
When a piece of gold was hit with particles most of the particles passed through the gold foil showing gold atoms are mostly empty space. -
Bohr's Planetary model
Electrons circle the nucleus in a path called a orbit -
Mosley's atomic Number
The atomic number of an element is the number of positive charges. -
Discovery of the proton
Ernest Rutherford discovery the proton in the early 1900's. During his experiments he was the first person to split an atom. -
Charge of the electron
The electron is negatively charged
1.602176634 × 10−19 coulomb -
Robert Millikan
Robert Millikan was an American physicist that discovered the falling drop method. -
Schrodinger Equation
equation that governs the function of a quantum-mechanical system -
heisenberg uncertainty principle
we cannot know both the position and speed of a particle, such as a photon or electron, with perfect accuracy -
Discovery of the neutron
the core contained a uncharged particle