Cathode Ray Video http://www.youtube.com/watch?v=_B0o81loJi8&feature=related

J.J. THOMPSON discovered NEGATIVELY charged particles, ELECTRONS, which are a part of every atom

Used the CRT and said ALL atoms have a negative charge (electron) Used the CRT and said ALL atoms have a negative charge (electron). This meant that all matter SHOULD have a NEGATIVE charge…which wasn’t true. Thomson revised Dalton’s model to include a SPHERE with POSITIVE charges and negatively charged electrons spread EVENLY throughout the atom. The negatively charged electrons and the POSITIVE charge in the sphere NEUTRALIZE each other

J. J. THOMPSON’S Atom Model Like a chocolate chip cookie!!!

J.J. Thomson Discovers Electrons http://www.chem.uiuc.edu/clcwebsite/cathode.html

D. Ernest RUTHERFORD tested Thomson’s model, and discovered it was not a solid ball…but mostly EMPTY space!!! “It’s about as believable as if you had fired a 15 in. shell at a piece of tissue paper and it came back and hit you.”

Rutherford experiment video http://video.google.com/videoplay?docid=-1909836802101196671

E. An atomic model with a NUCLEUS was developed.

RUTHERFORD Model

RUTHERFORD Model Rutherford learned from experiments that atoms contained a small, but heavy central positive NUCLEUS. He proposed that inside an atom all the PROTONS were gathered at the center (nucleus) of the atom, with the electrons scattered RANDOMLY around, just like the fruit of a peach is formed around the center pit.

The positively charged PROTON is located in a very small space at the CENTER of the atom (NUCLEUS). 2. Most of an atom is EMPTY SPACE occupied by nearly mass less ELECTRONS