Name
Date
Class
Content Vocabulary
LESSON 2
The Structure of Atoms
Directions: Use the terms below to complete the concept map. NOTE: You may need to change a term to its
plural form.
atomic number
isotope
charge
neutron
electron
nucleus
electron cloud
proton
ion
8.
that have gained or lost
electrons become
which have a positive
or negative
atoms
9.
have a central region
called
1.
5.
the number of these is
the same as the atom’s
2.
which contains particles called
4.
3.
have the same number of
these compared with other
atoms of the same element
have a region
surrounding the
central area called
which contains particles
called
6.
have different number of these
compared with other atoms of
the same element
7.
26
Matter and Atoms
Name
Date
Class
Lesson Outline
LESSON 2
The Structure of Atoms
A. The Parts of an Atom
1. Every kind of element is made up of its own kind of
.
2. Atoms are composed of several basic types of very small
; the
particles gives the different kinds of atoms their unique identity.
of each of these
3. The region at the center of an atom that contains most of the mass of the atom is
called the
.
a. A positively charged particle in the nucleus of an atom is called
a(n)
.
b. An uncharged particle in the nucleus of an atom is called
a(n)
.
4. A negatively charged particle that occupies the space in an atom outside the
nucleus is called a(n)
a.
.
are much smaller in size than
and neutrons, and they move very quickly.
b. The region surrounding an atom’s nucleus where one or more electrons are most
likely to be found is called a(n)
.
c. An electron cloud is mostly made up of
not a cloud of
d. The electrons closest to the
electrons farthest from the
space; it is
.
have the least energy; the
have the most energy.
B. The Size of Atoms
1. All the substances around you, including your body and the air you breathe are
made up of millions and millions of
.
2. If you could enlarge an atom to be 1 million times larger than its natural size, it
would be the size of a(n)
same degree would be the size of
Matter and Atoms
; this object enlarged to the
.
27
Name
Date
Class
Lesson Outline continued
C. Differences in Atoms
1. Every atom has a(n)
charged nucleus surrounded by
a(n)
charged electron cloud; however, atoms can have
different numbers of
, neutrons, and electrons.
2. The number of protons in the nucleus of an atom of an element is called
the
.
a. Each
has a different atomic number.
b. The number of
in the nucleus of the atom
determines the identity of the atom.
3. One of two or more atoms of an element having the same number of protons but
a different number of neutrons is called a(n)
.
4. A neutral atom has the same number of
as
in its nucleus
in its electron cloud.
a. A neutral atom can gain one or more
atom a(n)
more
charge.
, giving the
charge; a neutral atom can lose one or
, giving the atom a(n)
b. An atom that has a charge because it has gained or lost electrons is called
a(n)
.
c. Ions have same number of
and are the same element
they were before gaining or losing electrons.
D. Atoms and Matter
1. All atoms of the same element have the same number
of
.
2. For each element, the number of
and the number of
can vary.
3. The properties of an element and the ways its
combine
are determined mainly by the number and the arrangement of the
in its atoms.
28
Matter and Atoms
Name
Date
Class
Content Practice A
LESSON 2
The Structure of Atoms
Directions: On the line before each definition, write the letter of the term that matches it correctly. Each term is
used only once.
1. positively charged particle in the nucleus of
an atom
2. region surrounding an atom’s nucleus where one
or more electrons are often found
3. negatively charged particle that occupies the
space in an atom outside the nucleus
4. one or more atoms of an element having the
same number of protons but a different number
of neutrons
A. atomic number
B. electron
C. electron cloud
D. ion
E. isotope
F. nucleus
G. neutron
H. proton
5. region at the center of an atom that contains
most of the mass of an atom
6. an atom that has a charge because it has gained
or lost electrons
7. the number of protons in the nucleus of an atom
of an element
8. uncharged particle in the nucleus of an atom
30
Matter and Atoms
Name
Date
Class
Content Practice B
LESSON 2
The Structure of Atoms
Directions: Circle the term in parentheses that correctly completes each sentence.
1. The nucleus of an atom contains (protons/electrons) and neutrons.
2. The nucleus has a (positive charge/negative charge) and the (least mass/most mass)
of the atom.
3. An electron is a (positively charged/negatively charged) particle located outside the nucleus.
4. The modern model of an atom is called the (electron-cloud/nucleus-orbit) model.
5. Electrons that are close to the nucleus have (more energy/less energy) than electrons
that are farther from the nucleus.
6. The atomic number is the number of (protons/neutrons) in the nucleus of an atom
of an element.
7. Isotopes have the same number of protons but different numbers of (electrons/neutrons).
8. An ion has a charge because it has gained or lost (protons/electrons).
9. A (positive/negative) ion has more protons than electrons.
10. Adding a(n) (proton/electron) to a neutral atom produces a new element.
Matter and Atoms
31
Name
Date
School to Home
Class
LESSON 2
The Structure of Atoms
Directions: Use your textbook to respond to each statement.
1. All atoms have the same basic structure. The nucleus is the center region
of the atom.
Describe the nucleus by identifying the particles that are inside of it, its overall charge,
and its mass compared to the mass of an atom.
2. Electrons are one of the components of atoms. They are found in a region
of the atom called the electron cloud.
Describe electrons by identifying their charge and their relative mass compared to the
atom as a whole.
3. Elements are arranged in the periodic table in order of their atomic numbers.
Identify what can be learned about an atom of an element if its atomic number is
known.
4. Although every atom of an element has the same number of protons, the
atoms of an element can vary in other ways.
Identify how atoms can vary and what these types of atoms are called.
5. Atoms of an element can gain or lose electrons. An atom that has gained or
lost electrons is called an ion.
Describe how gaining an electron changes the overall charge on an atom.
Matter and Atoms
35
Name
Date
Key Concept Builder
Class
LESSON 2
The Structure of Atoms
Key Concept Where are protons, neutrons, and electrons located in an atom?
Directions: Label this diagram by writing the correct term on each line.
1.
2.
3.
Directions: Answer each question or respond to each statement on the lines provided.
4. Which particle in an atom has a positive charge?
5. Which particle in an atom has no charge?
6. Which particle in an atom has a negative charge?
7. Where is most of the mass of an atom found?
8. Describe the structure of the atom in the diagram above. How many of each type of
particle does the atom have?
36
Matter and Atoms
Name
Date
Class
Key Concept Builder
LESSON 2
The Structure of Atoms
Key Concept How is the atomic number related to the number of protons in an atom?
Directions: On each line, write the term or phrase that correctly completes each sentence.
1. The
is the number of protons in the nucleus of an atom of
an element.
2. You can identify an element if you know its atomic number or
3. In the periodic table, the atomic number of an element is the
above its symbol.
Directions: Complete the chart with the correct numbers on the lines provided.
Element
Atomic Number
magnesium
carbon
oxygen
Matter and Atoms
12
Number of Protons Number of Electrons
4.
6.
5.
6
8
7.
6
8.
37
Name
Date
Class
Key Concept Builder
LESSON 2
The Structure of Atoms
Key Concept What effect does changing the number of particles in an atom have on the
atom’s identity?
Directions: Complete the chart with the correct terms or numbers from the word bank on the lines provided.
Some terms or numbers may be used more than once or not at all.
isotope
5
negative ion
6
7
new element
9
8
positive ion
10
12
11
Possible Changes in Atoms
Neutron Atom
Change
carbon
6 protons
6 neutrons
6 electrons
add one proton
carbon
6 protons
6 neutrons
6 electrons
add one neutron
carbon
6 protons
6 neutrons
6 electrons
carbon
6 protons
6 neutrons
6 electrons
38
add one electron
lose one electron
Results
1.
2.
protons
3.
4.
neutrons
electrons
5.
6.
protons
7.
neutrons
8.
electrons
9.
10.
protons
11.
neutrons
12.
electrons
13.
14.
protons
15.
neutrons
16.
electrons
Matter and Atoms
Lesson 2: The Structure of Atoms
A. The Parts of an Atom
1. Every kind of element is made up of its own kind of atoms.
2. Atoms are composed of several basic types of very small particles; the number of each of these
particles gives the different kinds of atoms their unique identity.
3. The region at the center of an atom that contains most of the mass of the atom is called the
nucleus.
a. A positively charged particle in the nucleus of an atom is called a(n) proton.
b. An uncharged particle in the nucleus of an atom is called a(n) neutron.
4. A negatively charged particle that occupies the space in an atom outside the nucleus is called a(n)
electron.
a. Electrons are much smaller in size than protons and neutrons, and they move very quickly.
b. The region surrounding an atom’s nucleus, where one or more electrons are most likely to
be found, is called a(n) electron cloud.
c. An electron cloud is mostly made up of empty space; it is not a cloud of charge.
d. The electrons closest to the nucleus have the least energy; the electrons farthest from the
nucleus have the most energy.
B. The Size of Atoms
1. All the substances around you, including your body and the air you breathe are made up of
millions and millions of atoms.
2. If you could enlarge an atom to be 1 million times larger than its natural size, it would be the size
of a(n) orange; this object enlarged to the same degree would be the size of Earth.
C. Differences in Atoms
1. Every atom has a(n) positively charged nucleus surrounded by a(n) negatively charged electron
cloud; however, atoms can have different numbers of protons, neutrons, and electrons.
2. The number of protons in the nucleus of an atom of an element is called the atomic number.
a. Each element has a different atomic number.
b. The number of protons in the nucleus of the atom determines the identity of the atom.
3. One of two or more atoms of an element having the same number of protons but a different
number of neutrons is called a(n) isotope.
4. A neutral atom has the same number of protons in its nucleus as electrons in its electron cloud.
a. A neutral atom can gain one or more electrons, giving the atom a(n) negative charge; a
neutral atom can lose one or more electrons, giving the atom a(n) positive charge.
b. An atom that has a charge because it has gained or lost electrons is called a(n) ion.
c. Ions have same number of protons and are the same element they were before gaining or
losing electrons.
D. Atoms and Matter
1. All atoms of the same element have the same number of protons.
2. For each element, the number of electrons and the number of neutrons can vary.
3. The properties of an element and the ways its atoms combine are determined mainly by the
number and the arrangement of the particles in its atoms.
Content Vocabulary (page 26)
1. nucleus
2. electron cloud
3. protons
4. neutrons
5. atomic number
6. electrons
7. isotopes
8. ions
9. charge
Content Practice A (page 30)
1. H
2. C
3. B
4. E
5. F
6. D
7. A
8. G
Content Practice B (page 31)
1. protons
2. positive charge, most mass
3. negatively charged
4. electron-cloud
5. less energy
6. protons
7. neutrons
8. electrons
9. positive
10. proton
School to Home (page 35)
1. The nucleus contains protons and neutrons. It has an overall neutral charge, and it contains most of the
mass of the atom.
2. Electrons have a negative charge. They are very small; their mass is very tiny when compared to the mass
of the atom as a whole.
3. An element’s atomic number tells the number of protons in each atom of the element.
4. Atoms can vary by the number of neutrons in their nucleus. These atoms are called isotopes.
5. Gaining an electron gives an atom an overall negative charge.
Key Concept Builder (page 36)
1. proton
2. electron
3. neutron
4. proton
5. neutron
6. electron
7. in the nucleus
8. It has two protons, two neutrons, and two electrons.
Key Concept Builder (page 37)
1. atomic number
2. the number of protons in its atoms
3. whole number
4. 12
5. 12
6. 6
7. 8
8. 8
Key Concept Builder (page 38)
1. new element
2. 7
3. 7
4. 7
5. isotope
6. 6
7. 7
8. 6
9. positive ion
10. 6
11. 6
12. 7
13. negative ion
14. 6
15. 6
16. 5