THE HISTORY OF THE ATOM. Greek Philosophers (400 B.C.). Aristotle- believed the everything was made of the 4 elements (air, fire, water, and land). Each substance contained a varying portion of each element.
Determined there were positive and negative charges in nature.
Law of conservation of matter- matter isneither created nor destroyed in anyprocess (you did anexperiment with the test tube and the flask)
Law of constant composition - any sample of agiven compound always contains the samepercent of each element by mass.
Created the Atomic Theory of Matter
Contains 4 postulate:
4. A given compound always has the same relative numbers and kinds of atoms. (Proust)
Isolated the proton.
Isolated the electron. (cathode tube in the journal)
Accidentally discovered that uranium gave off invisible rays. Photo plates were developed when put close to the sample of uranium. (journals)
Found the mass (grams) and the charge (columbs) of the electron. (Famous oil drop experiment done at he University of Chicago.)
Proved electrons were in energy levels around the nucleus. (The current model changes part of Bohr’s idea.)
Found the nucleus of the atom also contained neutral particles; he called them neutrons.