Name
Date
The Structure of the Atom
Before You Read
Review
Vocabulary
scientific law
Define the following terms.
describes a relationship in nature that is supported by many
experiments
theory
an explanation supported by many experiments; is still subject to
new experimental data, can be modified, and is considered
successful if it can be used to make predictions that are true
element
a pure substance that cannot be separated into simpler substances
by physical or chemical means
law of definite
proportions
law of multiple
proportions
states that regardless of the amount, a compound is always
composed of the same elements in the same proportion by mass
states that when different compounds are formed by a combination
of the same elements, different masses of one element combine with
the same mass of the other element in a ratio of small whole numbers
Describe three things that you already know about the atom.
1. Accept all reasonable responses.
2.
3.
The Structure of the Atom
43
Name
Date
The Structure of the Atom
Section 4.1 Early Theories of Matter
Main Idea
I&E 1.d, 1.k, 1.n
Details
Scan Section 1 of your text. Use the checklist below as a guide.
• Read all section titles.
• Read all boldfaced words.
• Read all tables and graphs.
• Look at all pictures and read the captions.
• Think about what you already know about this subject.
List three things you expect to learn about while reading the section.
1. Accept all reasonable responses.
2.
3.
New
Vocabulary
Dalton’s atomic theory
Use your text to define each term.
a theory proposed by John Dalton in 1808, based on numerous
scientific experiments, which marked the beginning of the
development of modern atomic theory
atom
the smallest particle of an element that retains the properties of
the element
Academic
Vocabulary
accurate
having a measured value close to the accepted value
conclude
making a judgment based on the information obtained
reveal
44
Define the following term.
to make something known
Early Theories of Matter
Name
Date
Section 4.1 Early Theories of Matter (continued)
Main Idea
The Philosophers
Use with pages 87–89.
Details
Summarize the effect that Aristotle had on the atomic theory
proposed by Democritus.
Aristotle rejected Democritus’ ideas because it did not agree with his ideas
on nature. He did not believe that the “nothingness” of empty space could
exist. He denied the existence of atoms. People accepted Aristotle’s
conclusions for 2,000 years, and the ideas of Democritus were not developed.
John Dalton
Use with pages 89–90.
List the main points of Dalton’s atomic theory.
1. All matter is composed of extremely small particles called atoms.
2. All atoms of a given element are identical in size, mass, and
chemical properties. Atoms of one element are different from
those atoms of any other element.
3. Atoms cannot be created, divided into smaller particles, or
destroyed.
4. Different atoms combine in simple whole-number ratios to form
compounds.
5. In a chemical reaction, atoms are separated, combined, or
rearranged.
Discuss Dalton’s ideas by completing the following paragraph.
After years of studying chemical reactions , Dalton was able to
accurately determine the mass ratios of the elements involved
in the reactions. His conclusions resulted in the atomic theory ,
atoms
in chemical reactions
rearrange
, but are not created,
which helped to explain that
separate, combine , or
destroyed , or
divided
.
The Structure of the Atom
45
Name
Date
Section 4.1 Early Theories of Matter (continued)
Main Idea
Details
Compare and contrast the atomic theories of Democritus and
Dalton. Mark an X under each name if a statement in the table
applies to that person’s theory.
Statement
All matter is made of tiny pieces.
Democritus
Dalton
X
X
Matter is made of empty space
through which atoms move.
X
Atoms cannot be divided.
X
X
Atoms cannot be created.
X
X
Atoms cannot be destroyed.
X
X
Different atoms combine in
whole-number ratios to form
compounds.
Defining the
Atom
Use with pages 90–91.
X
The properties of atoms vary
based on shape, size, and
movement.
X
Different kinds of atoms come
in different sizes and shapes.
X
Explain an atom by completing the following statements.
The atom is the smallest particle that retains the properties
of the element
When a group of atoms
unit
.
bond together
, the result is known as a
molecule
and act as a
.
R EAL-W ORLD CONNECTION
The experiments of the alchemists
revealed the properties of some metals and provided the foundation for the science of
chemistry. Although not successful, alchemy proved beneficial to science. Explain how
this example can be applied to modern research.
Accept all reasonable responses. Possible answer: Even research and experiments that do
not succeed add to our body of knowledge and provide useful information to later
researchers.
46
Early Theories of Matter
Name
Date
The Structure of the Atom
Section 4.2 Subatomic Particles and the Nuclear Atom
Main Idea
Chemistry 1.e, 1.h, 11.g; I&E 1.n
Details
Scan Section 2 of your text. Use the checklist below as a guide.
• Read all section titles.
• Read all boldfaced words.
• Read all tables and graphs.
• Look at all pictures and read the captions.
• Think about what you already know about this subject.
Write three facts you discovered about subatomic particles.
1. Accept all reasonable responses.
2.
3.
New
Vocabulary
cathode ray
Use your text to define each term.
ray of radiation emitting from the cathode end of a tube used by
researchers to study mass and charge
electron
negatively charged particles that are part of all forms of matter
nucleus
tiny, dense, centrally located region within the atom that contains all of
an atom’s positive charge and virtually all of its mass
proton
a subatomic particle carrying a charge equal to but opposite that of an
electron; that is, a positive charge of 1+
neutron
a subatomic particle with a mass nearly equal to that of a proton,
but that has no electrical charge
Academic
Vocabulary
concentrate
Define the following term.
to build up or combine substances at one location or into one mass
The Structure of the Atom
47
Name
Date
Section 4.2 Subatomic Particles and the Nuclear Atom
Main Idea
Discovering the
Electron
(continued)
Details
Summarize the information you learned from cathode ray experiments. Use Figure 4-8 for reference.
Use with pages 92–94.
Cathode Ray
Experiment
Cathode ray is deflected
toward the positively
charged plate by an
electric field.
Altering the gas in the
tube and the material
used for the
cathode have no effect.
Proves:
Cathode ray is
deflected in a
magnetic field.
Proves:
Particles in the ray
Cathode rays have a
are part of all matter.
negative charge.
Indicates:
Cathode ray is composed of charged particles.
Identify the major discoveries about subatomic particles made by
the 19 th century.
1. Cathode rays were actually a stream of charged particles.
2. The particles carried a negative charge.
3. There were particles smaller than atoms.
48
Subatomic Particles and the Nuclear Atom
Name
Date
Section 4.2 Subatomic Particles and the Nuclear Atom
Main Idea
The Nuclear Atom
Use with pages 94–95.
Details
Describe Rutherford’s model of the atom by completing the following statements.
1. Most of an atom consists of
empty space
through
held
2. The electrons are
3. The volume of
Use with pages 96–97.
moving
rapidly
within the atom by their attraction
nucleus
space
larger
is many times
electrons
.
to the positively charged
Completing the
Atom—The
Discovery of
Protons and
Neutrons
(continued)
.
through which the electrons move
than the volume of the
nucleus
.
Organize the properties of subatomic particles by completing the
table below. Use Table 4-1 for reference.
Electron
Proton
Neutron
e
p
n0
Location
surrounding
the nucleus
in nucleus
in nucleus
Relative
electrical
charge
1
1
0
Symbol
Summarize what you have learned about subatomic particles by
completing the following paragraph.
Atoms have a
spherical
is made up of
protons
neutrons
that have no
99.97%
charge
. The nucleus makes up
atom
of the mass of an atom. Most of an
positively
electrons
charged nucleus. The
attraction
of an atom
that have a positive charge and
made up of negatively charged
by their
nucleus
shape. The
is
traveling around the
electrons
are held in place
to the positive charge of the
The mass of the protons and neutrons are almost
each other while the mass of the electrons is
nucleus
.
equal
to
extremely small .
The Structure of the Atom
49