Question | Answer |
Fundamental Particles Mass and charge | Proton:1,1
Neutron: 1,0
Electron:0,-1 |
Humphrey Davy | passed electricity through compounds and noted and concluded that:
the compounds decomposed into elements.
compounds are held together by electrical forces |
Michael Faraday | realized that the amount of reaction that occurs during electrolysis is proportional to the electrical current passed through the compounds |
Cathode Ray Tubes experiments | Consist of two electrodes sealed in a glass tube containing a gas at very low pressure.
When a voltage is applied to the cathodes (negative electrode) a glow discharge is emitted. |
Modifications to the basic cathode ray tube experiment | J.J. Thomson modified by adding two adjustable voltage electrodes.
Studied the amount that the cathode ray beam was deflected by additional electric field. "father of the electron" |
Thomson's Modification discovered... | charge:mass ratio of e. Studying the degree of deflections of cathode rays in different strengths of electric and magnetic fields, Thomson determined the ratio of the charge of the electron to its mass. e/m = -1.75882 x 108 coulomb/g |
Canal Rays and Protons | Eugene Goldstein noted streams of + particles in cathode rays move in opposite direction of cathode.
Called “Canal Rays” cause they passed through holes drilled through the - electrode.
Canal rays must be + called the “proton”. |
Millikan oil-drop experiment | Determined the charge and mass of e
charge on a single electron = -1.60218 x 10-19 coulomb.
Using Thomson’s charge to mass ratio we get that the mass of one electron is 9.11e-28 g.
e/m = -1.75882e8 coulomb
e = -1.60218e-19 coulomb
m = 9.10940e-28 |
Rutherford and the Nuclear Atom
Rutherford’s major conclusions from the beta-particle scattering experiment | The atom is mostly empty space.
It contains a very small, dense center called the nucleus.
Nearly all of the atom’s mass is in the nucleus.
The nuclear diameter is 1/10,000 to 1/100,000 times less than atom’s radius |
Rutherford model of the atom | Atoms consist of very small, very dense positively charged nuclei surrounded by clouds of electrons at relatively large distances from the nuclei |
Atoms | consist of very small, very dense positively charged nuclei surrounded by clouds of electrons at relatively large distances from the nuclei (Rutherford) |