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b.c Democritus
Speculated the theory of atoms stating that all matter is made up of atoms. Also stated that atoms are infinite, invisible, and so small that they can't be divided, and they entirely fill up the space they're in. -
John Dalton
*Proposed the 1st model of the atom. Stated:
1) That all matter was composed of small particles called "atoms" 2) Atoms of given elements are identical in size, mass, & other properties 3) Atoms can't be subdivided, created, or destroyed 4) Atoms of different elements combine to form chemical compounds 5) In chemical terms Atoms are combined, separated, or rearranged
*Dalton expanded on the Greek idea of the atom -
J.J Thompson
*Discovered the electron
-Developed the plum pudding-model of the atom
-Describes the atom as a slightly positive sphere with small electrons inside
*Took the idea of the atom and tried to join the evidence for the electron -
Ernest Rutherford
*Indicated a small, dense positively-charged nucleus as the result of the alpha particle scattering gold foil experiment
- used the results of his gold-foil experiment to state that all the mass of an atom were in a small positively-charged ball at the center of the atom. -
Neils Bohr
*The model focuses on quantization of energy of electrons
-He stated that electrons could only orbit the nucleus in successively larger orbits around the nucleus.
- Bohr corrects the critical flaw in Rutherford's model -
Warner Heisenberg
*His contribution to the atomic theory was that he calculated the behavior of electrons, and subatomic particles that also make up an atom.
-He included quantum mechanics to the atomic theory
-His model brought math more into understanding the patterns of an atom's electrons -
Erwin Schrodinger
*Took the Bohr atom model a step further and created the "Electron Cloud Model"
-Viewed electrons as continuous clouds and introduced "wave mechanics" as a mathematical model of the atom
- Used mathematical equations to describe the possibility of finding an electron in a certain position
