Chemistry C1

Discovery of the Atom

1) Democritus 

- a ball/sphere

2) Thompson

- plum pudding model 

- positive nucleas with a cloud of negative electrons sourrounding it

- atoms contain electrons

- atoms are neutral overall

3) Rutherford and Geiger and Marsden

- experiment: firing alpha particles at a thin peice of gold foil

- most particles fired back (like particles repel)

- some particles went through the foil (empty space between particles)

- atoms had a postive nucleas with electrons sorrounding it in elipse orbits

4) Neils Bohr

- shells orbit the nucleas in fixed shells

Chemical and Physical Changes:

Chemical:                                                   Physical:          

produces one or more substances             change in state or shape - no new substances made

difficult or impossible to reverse                 most are reversible

example…