Chapter # 14 Section #1
Name__________________________________
Pages 404-413
Fill in the blanks to complete each sentence. You may need to place several words in a blank to
complete the sentence.
Models of the Atom
Dalton’s Contribution
Dalton’s Concept of Matter
1._________________________________________________________________________________
2._________________________________________________________________________________
3._________________________________________________________________________________
4._________________________________________________________________________________
5. Make a drawing which represents Dalton’s model of the atom.
Crookes’ Contribution
6. Crookes’ cathode ray tube produced a_________________________________________________.
7. When Crookes’ placed a metal cross in the cathode ray tube and connected the tube to a power
source the cross produced ___________________________________________________________.
8. Crookes hypothesized that the green glow in the tube was caused by _______________________.
9. Crookes called the green glow __________________ rays.
10. Make a drawing that illustrates Crookes’ experiment. Label the parts of your drawing.
JJ. Thomson’s Contribution
11. Thomson carried out his experiment to determine if the cathode rays/green glow was__________
or __________________________________.
12. Thomson placed a magnet near Crookes’ cathode ray tube. The magnet ____________________
the beam in the tube.
13. Light __________________ be bent by a magnet.
14. So Thomson concluded that the beam was made up of ______________________________.
15. Make a drawing that illustrates Thomson’s experiment. Label the parts of your drawing.
Thomson repeated his experiment using different metals. He found that charged particles are
produced no matter which elements are used.
16. Thomson concluded that cathode rays are _____________________________ charged particles.
17. These negatively charged particles are now called ____________________________________.
18. Thomson’s experiments proved that particles __________________ than the atom do exist.
19. Thomson realized that the negatively charged electrons and the unknown _______________
charge would then neutralize each other in the atom.
20. Make a drawing of Thomson’s model of the atom. Label the parts and indicate the charge of each
part.
Rutherford’s Contribution
21. To test Thomson’s model Rutherford fired _____________________ at a thin film of ________.
22. What is the charge of an alpha particle? ________________________________
23. Rutherford predicted that all of the alpha particles would _________________________ the foil
and hit the screen on the other side.
24. He thought that the thin gold foil did not contain enough _____________ to stop the alpha
particles.
25. Rutherford was wrong, some of the alpha particles instead ____________________ the foil at
large angles.
26. He hypothesized that almost all of the atom’s mass is crammed into a small space in its center
called the _____________________________.
27. Based on the results of his experiments Rutherford proposed a new model of the atom. Draw the
model of the atom that he proposed and label its parts.
28. In 1920 scientists identified the positive charge in the nucleus as a _____________________.
29. Does the mass of an electron balance the mass of a proton? ____________
30. Rutherford’s model of the atom didn’t account for the huge amount of mass at the center of the
atom. It was proposed that another particle must be in the nucleus to account for the added mass,
the ________________.
31. What is the charge of a neutron? ____________
32. Draw and labeled the new updated model of the atom. Yes….label the parts AND indicate the
charge of each part.
Bohr’s Contribution
33. A group of physicists were working on a way to explain how electrons move around the nucleus.
One of the group Neils Bohr calculated exactly what energy levels those _______________ would
represent for the hydrogen atom..
Draw the Bohr model of the atom. (We will do this in class later.)
Electron Cloud Model
34. Where are electrons found in the electron cloud model of the atom?
35. Draw the electron cloud model. ( We will do this together in class.)