Name:____________________________
Date:___________
Period:____
Review Chemistry I
Unit 3: Atomic Theory and Structure
Define each of the following terms:
1. atom:
2. proton:
3. electron:
4. neutron:
5. nucleus:
6. average atomic mass:
7. isotope:
8. mass number:
9. atomic number:
10. Avogadro’s number:
11. molar mass:
Circle or write in the correct answer:
12. Which of the following was originally a part of Dalton's atomic theory, but had to be revised later
based on new experimental evidence? (circle all that apply)
A.
B.
C.
D.
Atoms are tiny indivisible particles.
Atoms of the same element are identical.
Atoms of different elements can sometimes be identical.
Compounds are made by combining atoms.
13. Consider J.J. Thomson’s cathode ray tube experiment. Briefly describe what occurred that gave
evidence of electrons in all atoms.
___________________________________________________________________
___________________________________________________________________
1
14. Which of the following is FALSE about subatomic particles?
A.
B.
C.
D.
Electrons are negatively charged and are the lightest subatomic particle.
Protons are positively charged and have nearly the same mass as neutrons.
Neutrons have no charge and have no mass.
The mass of a neutron nearly equals the mass of a proton.
15. All atoms are neutral because the number of __________________ always equals
the number of __________________ in every atom.
Fill in the chart with a charge and mass:
Proton
Neutron
Electron
Charge (+ , – , or 0 ) Mass (1 or 0)
____
____
____
____
____
____
Rutherford Gold Foil Experiment
gold
atom
expected results
gold
atom
actual results
16. What observations in this experiment by led to the theory that atoms are mostly empty space,
and that almost all of the mass of the atom is contained in a tiny, dense nucleus?
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
17. Based on Rutherford’s discovery of the nucleus, which model of the atom is thought to be true?
A.
B.
C.
D.
Protons, electrons, and neutrons are evenly distributed throughout the atom.
The nucleus is made of protons, electrons, and neutrons.
Electrons are located around the nucleus and occupy most of the volume.
The nucleus is made of electrons and protons.
2
18. All atoms of the same element have the same ____.
A.
B.
C.
D.
number of neutrons
number of protons
mass numbers
mass
19. What are atoms of the same element with different numbers of neutrons?
A.
B.
C.
D.
ions
atoms
numbers of electrons
isotopes
20. Explain why isotopes of the same element are not considered different elements.
___________________________________________________________________
___________________________________________________________________
75
35X
21. Element X has an atomic number of 35 and a mass number of 75.
How many of each subatomic particle are in a neutral atom of the element?
A.
B.
C.
D.
35 protons, 35 neutrons, and 70 electrons
35 protons, 75 neutrons, and 35 electrons
75 protons, 35 neutrons, and 40 electrons
35 protons, 40 neutrons, and 35 electrons
22. In which of the following is the number of neutrons correctly represented?
A.
F has 9 neutrons.
B.
As has 108 neutrons.
C.
Mg has 12 neutrons.
D.
U has 238 neutrons.
23. The weighted average atomic mass of the element chlorine is 35.45 amu, but the mass number of
a chlorine-37 atom is 37.
So how is the average atomic mass of an element different from the mass number of an atom?
___________________________________________________________________
___________________________________________________________________
24. Which of the following statements about atoms is FALSE?
A.
B.
C.
D.
Atoms of the same element can have different masses.
Isotopes of an element have different numbers of protons.
The nucleus of an atom has a positive charge.
Atoms are mostly empty space.
3
25. Which of the following statements about atoms and subatomic particles is FALSE?
A.
B.
C.
D.
Protons have a positive charge.
Electrons are negatively charged and have a mass of 1.
The nucleus of an atom is positively charged.
Neutrons are located in the nucleus of an atom.
26. 15 moles of sodium and 15 moles of carbon have the same number of _________.
A.
B.
C.
D.
atoms
grams
molecules
ALL of the above
27. _____________________ is the particles or energy emitted from an atomic nucleus when it is
unstable due to stronger ________________ repulsive forces than ______________ attractive forces.
28. Draw a line to match the name to the Greek symbol to the description to the symbol for each type
of radiation:
Name/Type
Greek letter
Alpha particle

Beta particle

Gamma ray

Description
Helium nucleus
Symbol
0
0𝛾
Energy
0
−1𝑒
Electron
4
2𝐻𝑒
29. The three radioactive emissions from question 2 were shot from the left side of Figure 1.
Cross out the symbol of each emission in the boxes based of the ability of different materials
to stop the emission from penetrating.



Single sheet
of paper



Single sheet of
Aluminum Foil



three feet
of concrete
concretese
4
Calculations and Mole Conversions
SHOW ALL WORK
BOX your answer
molar mass
30. What is the molar mass of CaF2 ?
31. What is the molar mass of Fe3(PO4)2 ?
______________________________________________________________________
particle ↔ mole
32. Convert 4.50 moles of Fe to atoms of Fe.
33. Convert 4.03 x 1022 molecules of water to moles of water.
5
Calculations and Mole Conversions
SHOW ALL WORK
BOX your answer
gram ↔ mole
34. Convert 0.300 moles of S to grams of S.
35. Convert 652 g Sn(CO3)2 to moles of Sn(CO3)2 . (MM = 238.73 g/mol)
______________________________________________________________________
particle ↔ gram
36. What is the mass in grams of 3.42 x 1024 atoms of C ?
37. How many atoms of aluminum are in a 5.60 g sheet of aluminum foil?
38. How many molecules are in 237 g H2O (one cup of water)? (MM = 18.02 g/mol)
6
Calculations and Mole Conversions
SHOW ALL WORK
BOX your answer
Mix of all 6 Mole Conversion Types
39. How many atoms are in 1.85 mol Pb?
40. How many molecules are in 120 g H2O2? (MM = 34.02 g/mol)
41. How many moles is 2.12 x 1024 molecules of PABA (sun block ingredient)?
42. What is the mass in grams of 4.78 x 1022 molecules of capsaicin, C18H27NO3?
(MM = 305.41 g/mol)
(capsaicin makes chili peppers hot!!)
[Extra] What mass of gold would have the same number of atoms as 1000. g lead?
7
KEY
12. A, B
13. Every element released negatively charge cathode rays that bent toward a positive plate.
14. C
15. protons, electrons
proton +1 1
neutron 0 1
electron –1 0
16. Most of the alpha particles traveled through the gold atoms showing atoms are mostly empty space.
Very few positively charged alpha particles deflected revealing a tiny, dense, positive region in atoms.
17. C
18. B
19. D
20. They are isotopes b/c they have different numbers of neutrons, but they are the same element b/c they
have the same number of protons (same atomic number).
21. D
22. C
23. Average atomic mass is a “weighted” average of all atoms of an element that depends on the relative
abundance (amount) of each isotope of an element, but mass number is just the number of protons and
neutrons in one single atom of an element.
24. B
25. B
26. A
27. Radioactivity , electrostatic , nuclear
28.
Alpha  α  Helium nucleus 
Beta  β 
electron

Gamma   
energy

4
2𝐻𝑒
0
−1𝑒
0
0𝛾
29. In 1st box, cross out  . In 2nd box, cross out α and β . In 3rd box, cross out α , β , and 
30. 78.08 g/mol
31. 357.49 g/mol
32. 2.7 x 1024 atoms
33. 0.0669 mol
34. 9.62 g
35. 2.73 mol
36. 68.2 g
37. 1.25 x 1023 atoms
38. 7.92 x 1024 molecules
39. 1.11 x 1024 atoms
40. 2.12 x 1024 molecules
41. 3.52 mol
42. 24.3 g
Extra: 950.6 g
8