Solutions to p22 and 23

1. a. Democritus or Dalton

b. Bohr

c. Democritus

d. Rutherford

e. Rutherford

f. Thomson

g. Bohr

h. Dalton or Democritus

i. Thomson

j. Rutherford

2. a. T

b. T

c. F

d. T

3. a. T

b. T

c. T

d. F

4.

	Democritus	Thomson	Rutherford	Bohr
Drawing
Any (+) and (-)?	No	Yes	Yes	yes
Mass is concentrated in...	Evenly distibuted	Evenly distibuted	In nucleus	In nucleus
Improves model with....	-------	Presence of electrons	Small but massive nucleus	Energy levels for electrons

5. a. It has electrons and positive charges.

b. In Rutherford's model, the mass and positive charge are concentrated in a small nucleus. Thomson's model proposes no nucleus. His assumption was that mass was evenly distributed throughout the atom.

6. a. Some alpha particles did not make it through the gold foil.

b. He expected all the alpha particles to penetrate the thin foil because alpha particles are very energetic, and the positive charge within the atom that could have repelled the alpha particles was supposedly spread out very thinly and evenly.