Name:______________________________Class:__________________ Date:__________________
Assessment
Subatomic Physics
Teacher Notes and Answers
22 Subatomic Physics
9. The more-massive nuclei have more protons
in their nucleus, and so have greater
repulsive forces within them. More neutrons
are needed to provide more of the strong
force that holds nucleons together without
causing any more repulsion.
10. 167.41 MeV
Given
21
For 10
Ne :
Z = 10
A = 21
atomic mass of Ne-21 = 20.993 841 u
Solution
N = A 2 = 21 10 = 11
THE NUCLEUS
1. b
2. d
3. b
4. a
5. c
6. c
7. b
Given
For 52
24 Cr :
Z = 24
A = 52
atomic mass of Cr-52 = 51.940 511 u
atomic mass of H = 1.007 825 u
atomic mass of mn = 1.008 665 u
Solution
N = A Z = 52 24 = 28
m = Z(atomic mass of 11 H ) + Nmn atomic mass
= 10(1.007 825 u) + 11(1.008 665 u) 20.993 841 u
= 10.078 250 u + 11.095 315 u 20.993 841 u
= 0.179 724 u
Ebind = (0.179 724 u)(931.49 MeV/u) =
m = Z(atomic mass of 11 H ) +
Nmn atomic mass
= 24(1.007 825 u) + 28(1.008 665 u) 51.940 511 u
= 24.187 800 u + 28.242 620 u 51.940 511 u = 0.489 909 u
8. d
Given
m = 0.466 769 u
c2 = 931.49 MeV/u
Solution
Ebind = mc2(0.466 769 u)
(931.49 MeV/u) = 434.79 MeV
167.41 MeV
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
1
Section Quizzes
Name:______________________________Class:__________________ Date:__________________
Assessment
Subatomic Physics
Section Quiz: The Nucleus
Write the letter of the correct answer in the space provided.
_____ 1. Which of the following statements correctly describes the relationship
between the three nuclear quantities?
a. Atomic number equals the mass number plus the neutron number.
b. Mass number equals the atomic number plus the neutron number.
c. Neutron number equals the mass number plus the atomic number.
d. Mass number equals the neutron number minus the atomic number.
_____ 2. The mass number of a given isotope is equivalent to which of the
following?
a. the precise mass of the nucleus in atomic mass units
b. the number of protons in the nucleus
c. the number of neutrons in the nucleus
d. the number of protons and neutrons in the nucleus
_____ 3. What is the energy associated with the mass of a subatomic particle
called?
a. internal energy
b. rest energy
c. nuclear energy
d. binding energy
_____ 4. Which of the following statements correctly describes the necessary
condition for a nucleus to be stable?
a. The number of neutrons must increase more than the number of
protons.
b. The number of neutrons must equal the number of protons.
c. The number of neutrons must increase less than the number of
protons.
d. Nuclear stability does not depend on the number of neutrons.
_____ 5. What force binds nucleons together in a nucleus?
a. gravitational force
b. Coulomb force
c. strong force
d. weak force
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
2
Section Quizzes
Name:______________________________Class:__________________ Date:__________________
Subatomic Physics continued
_____ 6. Why is the mass of a nucleus different than the sum of the masses of
the nucleons that make up the nucleus?
a. Some nucleons undergo beta decay, and so increase the nuclear
mass.
b. Some nucleons undergo beta decay, and so decrease the nuclear
mass.
c. Part of nucleon mass is converted to binding energy within the
nucleus.
d. The nucleus absorbs particles not bound to individual nucleons.
_____ 7. The atomic mass of
52
24 Cr
is 51.940 511 u. What is the mass defect for
this isotope? (atomic mass of 11 H = 1.007 825 u; mn 1.008 665 u)
a. 0.244 954 u
b. 0.489 909 u
c. 0.979 818 u
d. 1.959 636 u
_____ 8. The mass defect for a particular isotope is 0.466 769 u. What is the
binding energy in MeV for the nucleus of this isotope?
(c2 = 931.49 MeV/u)
a. 5.0109 104 MeV
b. 5.0109 MeV
c. 217.40 MeV
d. 434.79 MeV
9. Explain why the number of neutrons required for stability by more-massive
nuclei differs from the number of neutrons required for stability by lessmassive nuclei.
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
_________________________________________________________________
10. Calculate the binding energy of a
21
10 Ne
nucleus. (c2 = 931.49 MeV/u; atomic
21
mass of 10
Ne = 20.993 841 u; atomic mass of 11 H = 1.007 825 u;
mn = 1.008 665 u)
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Physics
3
Section Quizzes