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Democritus created Democritus' Atomic Theory, which stated that everything is composed of atoms. -
Introduced theory in which ideal geometric forms serve as atoms. -
Preformed experiments in which the goal was to change the structure of metals and ores to increase their value. Created a scientific process which would lead to discovery of the atom. -
Created Boyle's law, which stated that atoms must exist based on the relationship between the pressure and volume of gas. -
Discovered the role oxygen plays in combustion. Named oxygen(1778), and hydrogen(1783). -
Created Dalton's Atomic Theory, which was the first complete attempt to describe all matter in terms of atoms and their properties. -
Created by John Dalton He envisioned atoms as solid hard spheres, like billiard balls, so he used wooden balls with holes to model atoms. -
Created Avogadro's law, which corrected a problem with Dalton's theory. He made it possible to accurately estimate the atomic masses of elements and made a clear distinction between atoms and molecules. -
Created what we know today as the periodic table. -
Discovered subatomic particles during experiments with cathode ray deflection. -
Deduced that radioactivity does not depend on how atoms are arranged into molecules, but rather that it originates within the atoms themselves. -
Created by J.J. Thomson. Model tried to account for 2 properties of atoms known at the time. Includes electrons surrounded by a volume of positive charge. -
Created Brownian Motion, which proved the existence of atoms. -
Using the oil-drop experiment, he created a way to measure an electron's charge accurately. -
His theory of the atomic nucleus proposed that most of the atom's mass is concentrated in a small, dense nucleus consisting of protons and neutrons. -
Created by Ernest Rutherford. Also known as Rutherford model. Describes an atom as a tiny, dense, positively charged nucleus, in which nearly all the mass is concentrated, surrounded by light, negatively charged electrons that circulate at some distance, much like planets revolving around the sun. -
Contributed to the atomic model. He was the first to discover that electrons travel in separate orbits around the nucleus. Also discovered that the number of electrons determines the properties of elements. -
Discovered that each element contains a unique positive charge. Asserted that the periodic table should be arranged in order of increasing atomic number. -
Created by Erwin Schrodinger and greatly contributed to by Werner Heisenberg. Says that we cannot know exactly where an electron is at any given time, but the electrons are more likely to be in specific areas. -
Introduced the first discovery of wave equation for electron movements. -
Formulated quantum mechanics in terms of matrices. Also discovered the uncertainty principle, which states that a particle's position and momentum cannot both be known exactly. -
Discovered neutrons using the polonium-beryllium-paraffin experiment.