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Aristoltle Disagrees
ARistlotle a Greek philospher who lived from 384 to 322 disagreed with Democritus. He beleived you would never end up with an invisble particle. -
440
Democritus Proposed the Atom
Democritus proposed that all atoms are small, hard particles made up of a single material formed into dfifferent shapes and sizes. -
Dalton Creates Atomic Theory
Dalton proposed that
•All substances are made of atoms. Atoms are small particles that canny be created, divided, or destroyed.
•Atoms of the same element are exactly alike, and atoms of different elements are different.
•Atoms join with other atoms to make new substances. -
Thomson Finds An Electron In an Atom
JJ Thompson discovered something that identified an error in Daltons theory. Using simple equipment he discovered electrons inside the atom. So atoms could be divuided into smaller parts. -
Rutherford
To test Thompsons theory, Ernest Ruhtherford designed an experiment to investigate the structure of the atom. He aimed a beam of positivly charged particles at a thin sheet of gold foil. -
Rutherfords Atomic Model
Rutherford revised the atomic theory and developed a new model of the atom. -
Bohr
Bohr suggested that electrons travel arouind a definite path around the nucleus of the atom. -
Mopdern Theory
Today we have discovered that electrons do not travel in a definite path but rather in an electron cloud in a roandom motion around the nucleus of an atom.