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Developed in Consultation
with Virginia Educators
Table of Contents
Virginia Standards of Learning Correlation Chart . . . . . . . . . . . . . 6
Standards of Learning
Chapter 1 Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Lesson 1
Atoms and Elements . . . . . . . . . . . . . . . . . . . . . . . . . . 10
PS.1m, PS.2a, PS.2b, PS.3a,
PS.3b, PS.4a
Lesson 2
Molecules, Compounds, and Mixtures . . . . . . . . . . . . 16
PS.2b
Lesson 3
The Periodic Table of Elements. . . . . . . . . . . . . . . . . . 20
PS.2f, PS.4a, PS.4b
Lesson 4
States of Matter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
PS.1a, PS.1b, PS.1d, PS.1g,
PS.1i, PS.2a, PS.2c, PS.2d,
PS.7b
Lesson 5
Physical and Chemical Properties. . . . . . . . . . . . . . . . 30
PS.1b, PS.1d, PS.2c, PS.2d,
PS.2e, PS.7b
Lesson 6
Chemical Bonds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
PS.2b, PS.2e, PS.2f, PS.4c
Lesson 7
Chemical Reactions and Conservation of Mass . . . . . 40
PS.1a, PS.1b, PS.1d, PS.5a,
PS.5b
Lesson 8
Acids, Bases, and Salts. . . . . . . . . . . . . . . . . . . . . . . . 47
PS.1a, PS.2b
Chapter 1 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Chapter 2 Force and Motion. . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
Lesson 9
Describing Motion . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60
PS.1c, PS.10a
Lesson 10
Newton’s Laws of Motion . . . . . . . . . . . . . . . . . . . . . . 65
PS.10b
Lesson 11
Work and Machines. . . . . . . . . . . . . . . . . . . . . . . . . . . 69
PS.10c, PS.10d
Chapter 3 Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
Lesson 12 Potential and Kinetic Energy . . . . . . . . . . . . . . . . . . . . 80
PS.6a
Lesson 13
Energy Transformations. . . . . . . . . . . . . . . . . . . . . . . . 84
PS.6b
Lesson 14
Heat and Temperature. . . . . . . . . . . . . . . . . . . . . . . . . 89
PS.1d, PS.7a, PS.7b, PS.7c
Lesson 15
Applications of Thermal Energy Transfer . . . . . . . . . . 95
PS.1n, PS.7c, PS.7d
Lesson 16
Nuclear Energy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100
PS.1n, PS.5c
Chapter 3 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
4
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Chapter 2 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
Standards of Learning
Chapter 4 Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
Lesson 17 Properties of Waves . . . . . . . . . . . . . . . . . . . . . . . . . 110
PS.8a, PS8.c, PS.9a
Lesson 18
Understanding Sound . . . . . . . . . . . . . . . . . . . . . . . . 114
PS.1m, PS.8b, PS.8c, PS.8d
Lesson 19
Electromagnetic Waves . . . . . . . . . . . . . . . . . . . . . . . 120
PS.6b, PS.9b, PS.9d
Lesson 20
The Behavior of Light . . . . . . . . . . . . . . . . . . . . . . . . 124
PS.6b, PS.9b, PS.9c, PS.9e
Chapter 4 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
Chapter 5 Electricity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 137
Lesson 21 Electricity and Magnetism . . . . . . . . . . . . . . . . . . . . . 138
PS.1f, PS.11.a, PS.11b, PS.11c
Lesson 22
Electric Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143
PS.11a, PS.11d
Lesson 23
Motors and Generators . . . . . . . . . . . . . . . . . . . . . . . 148
PS.1e, PS.11b, PS.11c
Lesson 24
Diodes and Transistors . . . . . . . . . . . . . . . . . . . . . . . 152
PS.11a, PS.11d
Chapter 5 Review . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156
Investigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
Investigation 1 Investigating Acids and Bases . . . . . . . . . . . . . . 161
PS.1a, PS.1.j, PS.1k, PS.1l,
PS.2b
Investigation 2 Investigating Force and Motion. . . . . . . . . . . . . . 171
PS.1b, PS.1d, PS.1f, PS.1g,
PS.1h, PS.1i, PS.1j, PS.1k, PS.1l,
PS.10c
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181
Duplicating any part of this book is prohibited by law.
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SOL: PS.1m, PS.2a, PS.2b, PS.3a,
PS.3b, PS.4a
Chapter 1 t -FTTPO
Atoms and Elements
Key Words tBUPNtFMFNFOUtOVDMFVTtQSPUPOtOFVUSPOtFMFDUSPOtBUPNJDOVNCFStBUPNJDNBTT
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Getting the Idea
Everything around you is matter. Matter is anything that has mass and volume. Mass
is the amount of matter in a substance. Volume is the amount of space the substance
occupies. All substances—everything you own, everything you touch, even you
yourself—are made of different types of matter.
Atoms and Elements
Atoms are the basic building blocks of most of the matter around you. There are
different kinds of atoms. Each kind of atom is an element. An element is one of the
basic substances that combine to form all other substances. Elements cannot be
broken down into simpler substances by ordinary chemical means. An element is a
pure substance—matter that has the same chemical composition throughout and
cannot be separated by physical means.
Scientists have discovered 117 elements. These elements are the building blocks
of the matter around you. About 90 of these elements are found in nature. Carbon,
oxygen, gold, silver, and iron are some naturally occurring elements. The remaining
elements are synthetic, or made by humans in the laboratory.
An atom is the smallest particle of an element that has all the properties of that
element. Each element is made up of atoms that differ from those of every other
element. To understand how the atoms of each element differ, you need to look at
the particles that make up an atom.
The picture below shows the structure of a carbon atom. Notice that this atom is
made up of three different kinds of particles.
Carbon Atom
Neutron
Proton (⫹)
Electron (⫺)
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Atoms and Their Parts
The center of the atom is called the nucleus. The nucleus of most atoms is made up of two
kinds of particles: protons and neutrons. Protons carry a positive (⫹) charge. Neutrons have
no charge. The masses of protons and neutrons are measured in atomic mass units (amu).
Each proton and neutron has a mass of about 1 amu.
Electrons are subatomic particles that move around in an area outside the nucleus.
Electrons have a negative (⫺) charge. The mass of electrons is insignificant compared to the
mass of protons and neutrons. The table below compares protons, neutrons, and electrons.
Characteristics of Subatomic Particles
Particle
Mass
Charge
Location
Proton
1 amu
⫹1
Nucleus
Neutron
1 amu
0
Nucleus
Electron
—
⫺1
Outside nucleus
Protons and neutrons, in turn, are made up of tiny particles called quarks. Every proton or
neutron consists of three quarks. Protons and neutrons are made of different combinations
of quarks. Quarks are not found separately in nature. However, they can be made and
observed by scientists in some labs.
Elements and Subatomic Particles
The properties, or characteristics, of an element are determined by the structure of its atoms.
The main difference between different elements is atomic number. Atomic number is the
number of protons in the nucleus of an atom. The number of protons in the nucleus is unique
for each element. Therefore, no two elements have the same atomic number. Carbon, for
example, has six protons and an atomic number of 6.
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Look at the carbon atom on page 10 again. Notice that the number of protons in the atom is
equal to the number of electrons. Because these numbers are equal, each positive charge in
the nucleus is balanced by a negative charge in the electrons around the nucleus. The atom
as a whole is electrically neutral and has no overall charge.
Atoms have mass. The atomic mass of an atom is equal to the number of protons and
neutrons in the nucleus. Each proton has a mass of 1 atomic mass unit (amu). Each neutron
also has a mass of 1 atomic mass unit (amu). The atomic mass is determined by counting
the protons and neutrons in an atom.
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The table below gives the atomic masses of several common elements.
Atomic Masses of Some Elements
Element
Protons
Neutrons
Electrons
Atomic Mass
Carbon (C)
6
6
6
12 amu
Oxygen (O)
8
8
8
16 amu
Sodium (Na)
11
12
11
23 amu
Potassium (K)
19
20
19
39 amu
Iron (Fe)
26
30
26
56 amu
Notice the letters in parentheses next to the name of each element in the table. These letters
are the chemical symbol for the element. A chemical symbol is a code, usually made up of
one or two letters, used to represent an element. Each element has its own chemical symbol.
C always represents carbon, Ca always represents calcium, Fe always represents iron,
and so on.
Atoms and subatomic particles are much tinier than the things you normally measure. This
is one reason that atomic masses are given in atomic mass units. There are more than a
hundred billion trillion atomic mass units in one gram. Scientists also use very small units
for distances in and between atoms. For example, the radius of an oxygen atom is about
60 picometers. A picometer is one billionth of a millimeter. Even smaller units are used to
measure subatomic particles.
Atomic Theory
Since that time, scientists have developed many different models of the atom as they have
learned more about matter. A model is a representation of something that can be used to
study, show, or explain how it functions. A model may be a diagram, a three-dimensional
object, or a computer simulation. A model may also be an idea or a mathematical formula.
All these kinds of models are used in science. Models are useful for describing atoms
because atoms are too small to be seen except with powerful electron microscopes.
Subatomic particles are even harder to study.
In 1803, the English chemist John Dalton published a new atomic theory. He studied the
way elements combined to form new substances. He kept careful records of the masses of
the combining elements and the products they formed. He stated that matter in the form of
elements is made of particles called atoms. These particles cannot be divided or destroyed.
He also stated that atoms of the same element are alike in mass, and those of different
elements differ in mass. Dalton also stated that elements combine in predictable ratios.
t $IBQUFSMatter
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Atomic theory is a set of scientific principles explaining the structure and behavior of atoms.
Atomic theory began in ancient Greece. Greek scientists thought that matter was made up of
tiny particles, called atoms, which could not be broken into smaller particles.
Lesson 1: Atoms and Elements
Like the ancient Greeks, Dalton believed that an atom could not be broken down into smaller
particles. Less than 100 years after Dalton published his atomic theory, another scientist
made a discovery that changed this idea.
Experiments done by another English scientist, J. J. Thomson, changed Dalton’s model.
Thomson showed that elements can be made to give off negative particles—electrons.
If atoms can give off electrons, then atoms are not indivisible. Although electrons have a
negative charge, atoms do not have a charge. Thomson realized that an atom must contain
positive charges to balance the negative electrons. His model described the atom as a
positively charged sphere that has electrons scattered through it. Think of raisins in a muffin.
The raisins are scattered throughout the muffin. This is similar to the way Thomson said
electrons were scattered in the atom.
In 1911, the atomic model was changed again. Ernest Rutherford, a scientist from New
Zealand, studied particles given off by radioactive elements. He found that when alpha
particles struck a thin piece of gold foil, most of the particles passed through the foil. Some
bounced back or bounced off sideways. If matter were completely solid, all the particles
would have bounced back. The fact that most particles went through the gold led Rutherford
to conclude that most of the atom is empty space. What about the particles that did not pass
through the gold? Rutherford said that a small part of the atom is solid and has a positive
charge. This is the nucleus of the atom. Rutherford also said that the electrons circled the
nucleus like tiny planets. Rutherford’s model is often called the planetary model of the atom.
The next model of the atom was developed by a Danish scientist, Niels Bohr. In the Bohr
model, electrons move around the nucleus in orbits called energy levels. An energy level is
a region around the nucleus in which electrons with similar amounts of energy are located.
Electrons in an atom can have only amounts of energy that fit one of these levels. The lower
their energy, the closer the electrons are to the nucleus. In the Bohr model, electrons can
shift position from one energy level to another. Higher-energy areas (those farthest from the
nucleus) can hold more electrons. The Bohr model is shown below.
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Bohr Model
Nucleus
(contains protons (+)
and neutrons)
Electron (–)
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The current model of the atom is the electron cloud model. This model was based on
calculations made by the Austrian scientist Edwin Schrodinger. According to the model,
electrons exist in an area around the nucleus of an atom called a “cloud.” Scientists describe
electrons as existing somewhere in the electron cloud at any given time. An electron can be
found anywhere within the electron cloud.
Electrons in the cloud absorb and release energy. This changes their locations within the
atom. When electrons move to lower levels, they emit energy. Scientists can detect the
energy absorbed or emitted as light, heat, or other forms of energy.
The electron cloud model explains why substances have color, release heat, or give off
different types of radiation. This model is not the end, however. The atomic model will
continue to change as scientists make new discoveries.
Neutron
Proton
Nucleus
Electron
Electron cloud
Discussion Question
Lesson Review
1.
What are the smallest building blocks of an element that have all the properties of that
element?
A. electrons
B. atoms
C. protons
D. neutrons
t $IBQUFSMatter
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The development of atomic theory is a good example of the way scientific knowledge grows.
What is the main feature of this process?
Lesson 1: Atoms and Elements
2.
Sodium is an element found in table salt. It contains 11 protons and 12 neutrons. How
many electrons are found in a neutral atom of sodium?
A.
1
B. 11
C. 12
D. 23
3.
Which of the following lists the development of the model of the atom in the correct order?
A. particle theory → atoms contain electrons → atoms are mostly empty space
→ electrons are scattered in a positively charged sphere
B. atoms contain electrons → particle theory → electrons are scattered in a positively
charged sphere → atoms are mostly empty space
C. particle theory → atoms contain electrons → electrons are scattered in a positively
charged sphere → atoms are mostly empty space
D. atoms are mostly empty space → particle theory → atoms contain electrons
→ electrons are scattered in a positively charged sphere
4.
Which of the following is not part of Rutherford’s model of the atom?
A. Atoms are mostly empty space.
B. The nucleus is in the center of the atom.
C. The nucleus has a positive charge.
D. Electrons are found in a cloud around the nucleus.
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5.
Which scientist said that electrons are found in distinct energy levels in an atom?
A. Bohr
B. Dalton
C. Rutherford
D. Thomson
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