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Philosophers who first proposed that matter was composed of minute particles


The spreading out of particles through random motion from regions of higher concentration to regions of lower concentration


Scientist who proposed the Atomic Theory

Atomic Theory

1. All matter is made up of very small particles called atoms. 2. Atoms are indivisible. 3. Atoms cannot be created or destroyed


Scientist who investigated cathode rays in vacuum tubes

Cathode rays

Streams of negatively charged particles called electrons

Properties of cathode rays

1. Form shadows. 2. Cause glass to fluoresce. 3. Cause a paddle wheel to turn. 4. Consist of charged particles.


Scientist who named the electron


Scientist who showed that electrons are negatively charged and measured the e/m of the electron


Scientist who measured the charge on the electron using his Oil Drop experiment


Scientist who proposed a simple "plum pudding" model of the atom


Scientist who discovered the nucleus of the atom and the existence of protons in the nucleus.

Expected result

Most of the alpha particles should pass straight through the thin foil. Some alpha particles should suffer slight deflections.

Actual result

Most of the alpha particles went straight through the metal foil. Some of the alpha particles were deflected at large angles. A few were reflected back along their own path.


Scientist who discovered the neutron


Relative Charge = +1. Relative Mass = 1. Located in the nucleus


Relative Charge = 0. Relative Mass = 1. Located in the nucleus


Relative Charge = -1. Relative Mass = 1/1838. Located outside the nucleus

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