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440
Unable to split partilces
Democritus thought you would end up with a particle that could not be split. -
Element proportions
Scientists learned that elements combine in certin proportions based on mass to form compounds. -
Daltons atomic theory published
Dalton published his atomic theory -
Daltons theory not totally correct
In the late 1800's scientists agreed that Daltons theory explained much of what they saw but not all. -
Mistake in Daltons theory
In 1897 J. J. Thomson showed there was a mistake in daltons theory thomson discovered small particled inside the atom. -
Vibration
In 1900 Max Planck, a professor of theoretical physics in Berlin showed that when you vibrate atoms strong enough, such as when you heat an object until it glows, you can measure the energy only in discrete units. He called these energy packets, quanta. -
Testing Thomsons theory
Ernest nRutherford decided to test thomsons theory -
Revision of the atomic theory
Rutherford revised the atomic theory -
Particle waves
In 1924 a Frenchman named Louis de Broglie thought about particles of matter. He thought that if light can exist as both particles and waves, why couldn't atom particles also behave like waves? -
Particle waves model
In 1926 the Austrian physicist, Erwin Schrödinger had an interesting idea: Why not go all the way with particle waves and try to form a model of the atom on that basis? -
No particles
In 1926, a German physicist, Max Born had an idea about 'psi'. Born thought they resembled waves of chance. These ripples moved along waves of chance, made up of places where particles may occur and places where no particles occured. -
Electrons Dont move in definate paths
scientists found that electrons do not move in definate paths -
Electrons
In 1913 Niels Bohr proposed electrons move around the nucleus in paths.