who discovered what Flashcards
who first suggested existence of atoms
Democritus
First Principle of Dalton’s Atomic Theory
All elements are composed of tiny indivisible particles called atoms
Second/third Principle of Dalton’s Atomic Theory
Atoms of the same element are identical. the atoms of any one element are different from those of any other element
Fourth Principle of Dalton’s Atomic Theory
Atoms of different elements can physically mix together or can chemically combine with one another in simple whole-number ratios to form compounds
Fifth Principle of Dalton’s Atomic Theory
Chemical reactions occur when atoms are separated, joined, or rearranged. Atoms of one element, however , are never changed into atoms of another element as a result of a chemical reaction
who discovered electrons
J.J. Thompson, using Cathode Ray Tube
who discovered charge of an electron
Robert A. Millikan, using oil drop experiment
who found evidence for a positively charged particle
E. Goldstein, also used cathode ray tube
who confirmed existence of neutron
James Chadwick
who showed atom was mostly empty space with a little positive charge condensed in the middle
Rutherford, using gold foil experiment
