Brief-Constructed Response
Atoms and Elements Review
Teacher Guide
Objectives assessed: The student will be able to:
• Describe that an atom is composed of a nucleus (containing protons and neutrons) and
electrons.
• Explain that all atoms of an element have the same number of protons in their nucleus.
• Describe ions as atoms of the same element with different numbers of electrons and different
charges.
Students will need about 20–25 minutes to complete this brief constructed response.
1. Describe the structure of an atom. Include in your description the name, location, number, charge
and mass of each of the subatomic particles.
Correct response(s):
Sample Correct Response: An atom consists of a very small nucleus surrounded by
electrons in a cloudlike region. The nucleus is made up of protons and neutrons. The
hydrogen atom is the only exception because it has no neutrons. Electrons have a very
small mass and a negative electrical charge. Protons and neutrons are much heavier and are
almost equal in mass. A proton has a positive electrical charge, and a neutron has no
electrical charge. The number of protons in the nucleus of an atom is the same as the atomic
number of that atom. The number of electrons in a neutral atom is the same as the number of
protons. The number of neutrons in the nucleus varies from atom to atom but is usually
greater than the number of protons.
Response scoring tool:
Score Content
4
Response correctly states the names of particles, their number, relative
mass, charge, and location of subatomic particles.
3
2
1
0
Response correctly identifies the subatomic particles and their locations
but may include one or two errors in mass, charge, and number.
Response correctly describes three or four of the listed characteristics of
subatomic particles.
Response correctly describes one or two of the listed characteristics of
subatomic particles.
No response, or response not appropriate to the question.
2. What feature of an atom of an element determines the identity of the element?
a. the number of electrons
b, the number of protons
c. the number of neutrons
d. the total numbers of protons and neutrons
[Answer: b]
Brief-Constructed Response: Concept Name
© 2010 Discovery Education
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Brief-Constructed Response
Atoms and Elements Review
Teacher Guide
3. Compare and contrast the atomic structure of an atom of oxygen and an ion of oxygen. Be sure
to include the following information:
• The number of protons
• The number of neutrons
• The number of electrons
Correct response(s):
Sample Correct Response: An atom of oxygen is similar to an ion of oxygen in because they
both have the same number of protons and neutrons in their nucleus; there are eight of
each. They differ from each other because an oxygen atom is stable. This means that the
number of protons is equal to the number of electrons in an atom of oxygen. An ion of
oxygen is unstable. This means that there is a difference between the number of protons and
electrons in an atom of oxygen. Since the ion of oxygen has a charge of -2, the ion has 2
more electrons than protons for a total of ten.
Response scoring tool:
Score Content
3
Response identifies; there are 8 protons, 8 neutrons and 8 electrons in a
stable atom of oxygen and 8 protons, 8 neutrons and 10 electrons in an
ion of oxygen. Similar- same number of protons and neutrons in the
nucleus. Differ- different number of electrons
2
Response indicates; only the number of protons, neutrons and electrons in
both the atom and the ion, but does not state specifically the similarities or
differences
1
Response indicates; the similarity and differences of the atom and the ion,
but there is no mention of the number of protons, neutrons or electrons.
0
No response, or response not appropriate to the question.
Teacher Notes: Students may find it useful to use a periodic table for this activity.
Brief-Constructed Response: Concept Name
© 2010 Discovery Education
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