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Period: 500 to 510
Democritus
Introduced that matter cannot be infinitely divided.
Used the word atomos but it later became atom.
Belived atoms were the smallest of matter and they cannot be created or destoyed.
Couldn't figure what holds atoms together -
Period: 525 to 560
Aristotle
Disputed with Democritus' about his ideas that atoms move through empty space.
Was narrow minded about science because of his opinions.
Slowed down the development of science and replaced Democritus' beliefs. -
Period: to
Dalton
Marks the beginning of modern atomic theory
Agreed with Democritus and modified Democritus' work with the research he did himself.
Changed Atomos to Atom and changed "atoms cannot be created, destroyed, or further divided" into "atoms are invinsible and indestructible." -
Period: to
J.J Thompson
A Cathod Ray Tube was designed because they carried a negative charge.
Proved Dalton's theory about atom's indivisbility, and concluded that the mass of the particle was much less than that of a Hydrogen atom. -
Period: to
Robert Millican
Designed a oil drop apparatus to determine the chrage of the electron.
He determined the magnitude of the charge of an electron was 1.602x10^-9 coulombs.
Discovered the mass of an electron using the charge mass ratio; 9.1x10^-28g -
Period: to
Ernest Rutherford
Studied how positively charged a-dashed particles interacted with solid matter.
Designed an experiment to see if a-particles would be deflected as they move through a thin sheet of gold foil.
He came to the conclusion that Thompson's Plum Pudding model of the atom was incorrect.
Rutherford calculated that an atom was mostly just empty space for electrons to move around in.
There had to be a place for the positive charge and the majority of the mass of an atom to recide, the nucleus. -
Nobel Prize
Thompson recived a Nobel Prize for the discovery of the electron.