Name ______________________________ Class___________________Date__________________
Skills Worksheet
Section Review
11-2
The Atom
USING KEY TERMS
1. Use the following terms in the same sentence: proton, neutron, and isotope.
The proton and neutron make up the nucleus
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of the atom. Each isotope has a different number
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of neutrons but the same number of protons.
Complete each of the following sentences by choosing the correct term from the
word bank.
atomic mass unit
mass number
atomic number
atomic mass
Atomic number
2. An atom’s ______________________
is equal to the number of protons in its
nucleus.
atomic mass
3. An atom’s ______________________
is equal to the weighted average of the
masses of all the naturally occurring isotopes of that element.
UNDERSTANDING KEY IDEAS
_____ 4. Which of the following particles has no electric charge?
a. proton
c. electron
b. neutron
d. ion
5. Name and describe the four forces that are at work within the nucleus of an
atom.
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MATH SKILLS
6. The metal thallium occurs naturally as 30% thallium-203 and 70% thallium205. Calculate the atomic mass of thallium. Show your work below.
203 x 0.30 = 60.9amu
205 x 0.70 = 143.5amu
Total = 204.4amu
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology
18
Introduction to Atoms
Name ______________________________ Class___________________Date__________________
Section Review continued
CRITICAL THINKING
7. Analyzing Ideas Why is gravitational force in the nucleus so small?
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8. Predicting Consequences Could a nucleus of more than one proton but no
neutrons exist? Explain.
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No. Like charges would repel each other and the nucleus would become
unstable.
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INTERPRETING GRAPHICS
9. Look at the two atomic models below. Do the two atoms represent different
elements or different isotopes? Explain.
These are different elements due to the different number of protons
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in each diagram.
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Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Science and Technology
19
Introduction to Atoms