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Unit 1
Section 1 The Methods of Science
A. _________________ studies natural patterns.
1. Science is classified into three main categories: ______________ science, _______________science, and ______________ science; sometimes a scientific study will overlap the categories.
2. Science explains the natural world; explanations can ________________ over time.
3. Scientists _____________________ nature by observation, experimentation, or modeling.
B. ___________________________—organized set of investigation procedures
1. _______________ a problem.
2. ________________ information.
3. Form a ____________________ or educated guess based on knowledge and observation.
4. An experiment with variables is a common way to ______________ a hypothesis.
a. A ___________________ variable changes value as other variables change.
b. An _____________________ variable is changed to determine how it will affect the dependent variable.
c. A variable that does not change when other variables change is a __________.
d. A _________________ is the standard to which test results can be compared.
5. _________________ data from an experiment or investigation.
6. Form a _____________________ based on the data.
7. Reduce ______________ by keeping accurate records, using measurable data, and repeating the experiment.
C. ________________ represent ideas, events, or objects and can be physical or computerized.
D. A ________________ is an explanation based on many observations and investigations; a _________________________ is a statement about something that always seems to be true.
E. Science deals with the _________________ world; questions of value or emotion cannot be answered.
F. ____________________—applied science helping people
Section 2 Standards of Measurement
A. __________________—exact quantity that people agree to use for comparison
B. Measurements must have a number and a ______________.
1. __________—an improved version of the metric system used and understood by scientists worldwide.
2. SI system is based on _________________________ and uses prefixes to indicate a specific multiple.
C. ________________ is measured using a unit appropriate for the distance between two points.
D. ________________—the amount of space an object occupies
E. ______________—measure of matter in an object
1. ________________—mass per unit volume of a material
2. A unit obtained by combining different SI units is called a ______________________.
F. __________is the interval between two events; _____________________ is measured using a thermometer.
Section 3 Communicating with Graphs
A. _______________—visual display of information or data that is used to detect patterns
B. A ______________ graph shows a relationship where the dependent variable changes due to a change in the independent variable.
1. The _______________ should make the graph readable.
2. The x-axis should ________________ be used for the independent variable.
3. Units of measurement must be ____________________.
C. _____________ graphs compare information collected by counting.
TOOLS OF MEASUREMENT
q 1) METRIC ___________ (LENGTH)
UNITS= CM OR MM
q 2) TRIPLE BEAM __________ (MASS) UNIT = KG OR GM
q 3) _______________CYLINDER (VOLUME) UNITS=L
q 4) ___________________ (TEMPERATURE) UNITS=DEGREES CELCIUS
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Unit 2
ch 2 Classification of Matter
Section 1 Composition of Matter
A. _______________________—either an element or a compound
1. When all the atoms in a substance are alike, the substance is an _______________________.
2. A _______________________ is a substance with two or more elements combined in a
fixed proportion.
B. Two or more substances that can be easily separated by physical means
form a _______________________.
1. _______________________ mixture—mixture of different and easily distinguishable materials
2. _______________________ mixture—contains two or more gaseous, liquid, or solid sub-stances
blended evenly; also called a solution
3. _______________________—heterogeneous mixture with larger particles that never settle;
colloids scatter light in the Tyndall effect
4. A heterogeneous mixture containing a liquid in which visible particles settle is
called a _______________________.
Section 2 Properties of Matter
A. _______________________—characteristics of a material which can be observed without
changing the identity of the substances in the material; examples include color, shape, size,
melting point, and boiling point
1. _______________________—physical description of a substance
2. _______________________—how a substance acts; for example, magnetism, viscosity, ductility
3. Physical properties such as size and magnetism can be used to _______________________
mixtures.
B. _______________________—change in a substance’s size, shape, or state of matter
1. Substance does not change _______________________ when it undergoes a physical change
2. _______________________ is a process for separating a mixture by evaporating a liquid
and condensing its vapor.
C. _______________________ property—characteristics of a substance indicating that it can
change chemically; for example, flammability or light sensitivity of a substance
D. When one substance changes to another substance, a _______________________ has occurred.
1. Some chemical changes are indicated by _______________________ change, smell, or
bubble formation.
2. Other chemical changes occur very slowly, such as the formation of
_______________________.
3. Chemical changes can be used to _______________________ substances such as metals
from their ores.
E. ______________ of Earth’s surface involves both physical and chemical changes.
1. ____________—big rocks split into smaller ones; streams carry rock particles from one
location to another
2. ____________—Chemical changes can occur in rocks when calcium carbonate in lime-stone
changes to calcium hydrogen carbonate due to acid rain.
F. Law of ________________________________________—Mass of all substances present
before a chemical change equals the mass of all substances after the change.
ch 3 Solids,Liquids,and Gases
Section 1 Kinetic Theory
A. ________________ of matter—solid, liquid, gas
1. _________________ theory—explains how particles in matter behave
a. All matter is composed of small ___________________.
b. Particles are in constant, random ________________.
c. Particles _________________ with each other and walls of their containers.
2. ________________________—total energy of a material’s particles; causes particles to
vibrate in place
3. Average kinetic energy—_____________________ of the substance, or how fast the
particles are moving; the lower the temperature, the slower the particle motion
4. _______________ state—particles are closely packed together in a specific type of
geometric arrangement.
5. ________________ state—a solid begins to liquefy at the melting point as the particles
gain enough energy to overcome their ordered arrangement.
a. Energy required to reach the melting point is called the heat of ________________.
b. Liquid particles have more space between them, allowing them to flow and take the
shape of their container.
6. _________________ state—a liquid’s particles have enough energy to escape the attractive
forces of the other particles in the liquid
a. Heat of ______________________ is the energy required for a liquid to change to a gas.
b. At the _______________________, the pressure of a liquid’s vapor is equal to the
pressure of the atmosphere, and the liquid becomes a gas.
c. Gas particles spread evenly throughout their container in the process
of ___________________.
7. Heating curve of a liquid—as a solid melts and a liquid vaporizes, the temperature remains
__________________; the temperature will increase after the attractive forces of the earlier
state have been overcome.
8. ________________—state of matter consisting of high-temperature gas with balanced
positively and negatively charged particles.
B. _________________ expansion—increase in the size of a substance when the temperature
increases
1. The size of a substance will then __________________ when the temperature decreases.
2. Expansion and contraction occur in ______________ solids, liquids, and gases.
3. _______________ is an exception because it expands as it becomes a solid.
C. Some substances do not react as __________________ when changing states.
1. ___________________ solids—lack the tightly ordered structure found in crystals
a. Do not have definite temperature at which they change from solid to liquid
b. Glass, plastic
2. ________________ crystals do not lose their ordered arrangement completely upon
melting; used in liquid crystal __________________ in watches, clocks, calculators, and
some notebook computers.
Section 2 Properties of Fluids
A. __________________—ability of a fluid (liquid or gas) to exert an upward force on an object
immersed in it
1. An object in a fluid will _______________ if its weight is less than the buoyant force acting
on it from the fluid.
2. An object in a fluid will ______________ if its weight is more than the buoyant force acting
on it from the fluid.
3. _____________________ principle—buoyant force on an object is equal to the weight of
the fluid displaced by the object.
4. An object will float if its _________________ is less than the density of the fluid it is placed in.
B. __________________ principle—pressure applied to a fluid is transmitted throughout the fluid
1. Pressure is _______________ exerted per unit area.
2. ___________________ machines use this principle to lift heavy loads.
C. _____________________ principle—as the velocity of a fluid increases, the pressure exerted
by the fluid decreases; airplanes use this principle to fly.
D. ___________________—a liquid’s resistance to flow
1. Molecular ___________________ determines a fluid’s viscosity.
2. Increased _____________________ will lower viscosity.
Section 3 Behavior of Gases
A. __________________ is measured in a unit called a pascal (Pa).
1. ____________________ of particles in air result in atmospheric pressure.
2. Moving particles colliding with the inside walls of a container result in _____________ pressure.
B. _________________ Law—relates pressure and volume
1. Volume decreases as __________________ increases.
2. Pressure decreases as ________________ increases.
3. Pressure multiplied by volume is always equal to a __________________ if the temperature
is constant.
C. ___________________ Law—relates volume and temperature
1. At a constant pressure, ________________ increases as temperature increases.
2. At a constant pressure, volume decreases as _____________________ decreases.
D. ______________________ Law—relates pressure and temperature; at a constant volume, as
temperature increases, pressure increases
ch ___
© Glencoe/ McGraw- Hill, a division of the McGraw- Solutions
Section 1 How Solutions Form
A. Solution—a mixture that appears the same throughout and is mixed at the
________________ level
1. _______________—substance being dissolved
2. ________________—substance doing the dissolving
3. Solutions can be liquids, gases, or _______________.
4. Alloys are ______________ solutions.
B. How dissolving happens:
1. Water molecules are ______________—they have a positive area and a negative area.
2. Water molecules cluster around ______________ molecules, with their negative ends
attracted to the positive ends of the solids.
3. Water molecules _____________ the solid particles into solution.
4. The moving ______________ molecules and ______________ molecules spread out and
mix evenly to form a _________________.
5. To mix solids to make an alloy solution, you must _____________ the solids.
C. Rate of dissolving depends on:
1. _________________—speeds up dissolving by bringing more fresh solvent into contact
with more solute.
2. Crystal _____________
a. Dissolving occurs at the ________________ of a solid.
b. Breaking a solid into pieces or powder increases its _____________________, which
speeds up dissolving.
3. Temperature—___________________ the temperature of a solvent speeds up the
movement of its particles.
4. To make a gas dissolve more quickly in a liquid, _____________ the liquid solvent and
_________________ the pressure of the gas.
Worksheet
Section 3 Solubility and Concentration
A. ___________________—the amount of a substance that can dissolve in a solvent
1. Depends on the nature of the ___________________
2. Solubilities of two substances can be compared by __________________.
B. Concentration
1. A _____________________ solution has a large amount of solute in the solvent.
2. A _______________ solution has a small amount of solute in the solvent.
3. Concentrations can be expressed as percent by _______________ of the solute.
C. Types of solutions
1. __________________ solution—contains all the solute it can hold at a given temperature.
a. As the temperature of a liquid solvent increases, the amount of solid solute that can dis-solve
in it __________________.
b. _________________________—line on a graph used to figure how much solute can
dissolve at any temperature on the graph
2. ____________________ solution—able to dissolve more solute at a given temperature
3. _______________________ solution—contains more solute than a saturated one at the
same temperature
a. Made by ________________ temperature of a saturated solution, adding more solute,
and lowering temperature back without ___________________ the solution
b. _________________—will crystallize if disturbed
c. As it crystallizes, it gives off _______________ and produces heat.
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Unit 3
Ch 18 properties of atoms and the periodic table
Section 1 Structure of the Atom
A. ____________ are abbreviated in scientific shorthand—first letter or two of element’s name
B. ________—smallest piece of matter that still has the properties of the element
1. ___________ have electrical charge of 1+.
2. ____________ do not have an electrical charge.
3. _____________ have electrical charge of 1-.
4. Protons and neutrons are in the ___________ of an atom; electrons surround the nucleus.
C. Protons and neutrons are made up of smaller particles called __________.
1. Quarks are studied by colliding accelerated charged particles with protons, which leave tracks in a __________________.
2. Six quarks are known to exist; the sixth is called the _______ quark.
D. Scientists use scaled-up __________ to represent atoms.
1. Early models of atoms used a solid __________.
2. Current __________________ model shows electrons traveling in specific energy levels around a nucleus of protons and neutrons.
Section 2 Masses of Atoms
A. _______________—composed mostly of the protons and neutrons in the nucleus
1. Unit of measurement for atomic particles is ____________________ (amu) which is one-twelfth the mass of a carbon atom containing six protons and six neutrons.
2. _________________—the number of protons in an atom; number of protons also identifies the element
3. The sum of the number of protons and neutrons in the nucleus of an atom is
the _______________.
B. ____________—atoms of the same element with different numbers of neutrons
1. Different isotopes have different ______________.
2. Number of ____________ is equal to mass number minus atomic number.
3. Name of ___________ followed by mass number identifies the isotope.
4. _______________________ is the weighted-average mass of an element’s isotopes.
1. Average atomic mass is closest to its most ____________ isotope.
Section 3 The Periodic Table
A. Elements are organized in the __________________ by increasing atomic number.
1. In the late 1800’s, Dmitri Medeleev devised the first periodic table based on
_______________.
2. In 1913, Henry G. J. Moseley arranged the elements by _________________ rather than atomic mass.
B. Vertical columns in the periodic table are __________ of elements with similar properties.
1. Elements in the same group have the same number of _____________ in their outer energy level.
2. Each of the seven energy levels can have a ___________ number of electrons.
a. Energy level one can contain at most _______ electrons.
b. Energy level two can contain at most _________ electrons.
3. Each row in the periodic table ends when an outer energy level is __________.
4. _________________________ use the element symbol and dots to represent outer energy
level electrons.
C. ___________—horizontal rows of elements that contain increasing numbers of protons and
electrons.
1. Elements are ______________ as metals, nonmetals, or metalloids (semimetals).
2. Elements are _______________ in laboratories all over the world.
D. The ________ elements exist all over the universe.
1. Hydrogen and helium are the ___________________ of other naturally occurring elements.
2. ______________ spread heavier elements throughout the universe.
CH 20 ELEMENTS AND THEIR PROPERTIES
Section 1 Metals
A. Properties of __________
1. ___________ heat and electricity
2. __________—reflect light well
3. _____________—can be hammered or rolled into sheets
4. ___________—can be drawn into wires
5. ____________ ____________—combine with nonmetals by losing electrons
6. ____________________—positively charged metallic ions are surrounded by a cloud of electrons; ions are in sliding layers and electrons are weakly held; readily form ionic bonds with nonmetals
B. The __________ Metals—softer and more reactive than other metals
1. Highly ____________ with oxygen and water; don’t occur naturally as elemental forms
2. Combine readily with other elements due to __________ electron in outer energy level
3. ____________ uses
a. Human health—__________, _____________, and ___________ compounds
C. The __________________ Metals—not found naturally in elemental form; _______ electrons
in outer energy level
1. Applications—_____________ and magnesium found in fireworks; _____________ in vehicles, ladders, and bats; ___________ in statues and countertops
D. ______________ Elements –they often occur in nature as uncombined elements
1. Typically form colored compounds—____________ found in rubies and emeralds
2. 2. Iron _________—iron, cobalt, and nickel
a. ________—most widely used of all metals and main ingredient in _________; abundant in Earth’s crust
b. ___________—only room temperature liquid metal; used in thermometers and batteries
E. The ____________________ Metals—seem disconnected from the rest of periodic tables
2. The _____________—all are radioactive and ____________; ___________ is the best known.
Section 2 Nonmetals
A. Properties of _____________—usually gases or ___________ solids at room temperature; are not malleable or ___________; usually poor ______________ of heat and electricity; usually not lustrous
1. _________ compounds—form when nonmetals gain _____________ from metals and become ____________ ions
2. ____________ compounds—form when nonmetals share electrons with
other ______________
B. ____________—most common element in universe
1. A _____________________—two atoms of the same element in ____________ bond
2. Highly ____________ element found mostly on Earth as part of water compound
C. The ____________—include bromine, iodine, ____________, ____________, and astatine
2. A ________ forms when a halogen gains one electron from a metal.
2. Use of halogens
a. ____________—disinfectant and bleach
3. ________________—a solid changes directly into a gas without first becoming a liquid
D. The _______________—exist as isolated, stable atoms
Section 3 Mixed Groups
A. Properties of ______________—form ionic and covalent bonds; have some metallic and some nonmetallic properties; partial conduction gives them _________________ characteristics.
B. The _______________—named for the first element in Group 13
1. _________—used in water softening products, antiseptics, and fuels
2. ____________—abundant in Earth’s crust; used in cans, foil wrap, pans, building materials,and aircraft
C. The __________ Group—four electrons in outer energy level
1. __________—found in coal, oil, natural gas, and foods
2. Silicon occurs as an allotrope—same element with different molecular structures
a. ___________ found in sand, rocks, and soil
b. The main component in __________________, which conduct electricity under certain conditions
D. The ____________ Group—five electrons in outer energy level; tend to form covalent bonds
3. . ____________ and ___________ used with other metals to lower their melting points
The __________ Group or Group 16
1. __________—makes up 20% of air, is used by living things in respiration, and provide protection from Sun’s radiation
F. _____________ Elements—scientists create elements not usually found on _________;synthetic elements usually disintegrate quickly.
3. ________________ elements have more than ______ protons and are synthetic and unstable.
a. The study of synthesized elements helps scientists to understand the __________ holding
the ___________ together.
b. Element 114 lasted for ______ seconds.
c. It combined 114 protons with _______ neutrons.
d. It broke apart due to enormous _____________ between the protons.
ch 19 Chemical Bonds
Section 1 Stability in Bonding
A. Some elements combine chemically and no longer have the same ___________________ they did before forming a compound.
B. A(n) _________________________ is composed of symbols and subscripts indicating the number of atoms of an element in a compound.
C. Atoms form compounds when the compound is more _______________ than the separate atoms.
1. Noble gases are more __________________________ than other elements because they have a complete outer energy level.
2. Elements that do not have full outer energy levels are more stable in __________________.
3. Atoms can lose, gain, or ______________ electrons to get a stable outer energy level.
4. A(n) ______________________ is the force that holds atoms together in a compound.
Section 2 Types of Bonds
A. A(n) ____________ is a charged particle because it has more or fewer electrons than protons.
1. When an atom ______________ an electron, it becomes a positively charged ion; a super-script indicates the charge.
2. When an atom ______________ an electron, it becomes a negatively charged ion.
B. An ionic compound is held together by the ___________________—the force of attraction between opposite charges of the ions.
1. The result of this bond is a(n) ________________ compound.
2. The sum of the charges on the ions in a unit of the compound is _____________.
C. __________________ are neutral particles formed as a result of sharing electrons.
1. A ______________________ is the force of attraction between atoms sharing electrons.
2. Atoms can form double or triple ______________ depending on whether they share two or three pairs of electrons.
3. Electrons shared in a molecule are held _____________________ to the atoms with the larger nucleus.
4. A(n) ______________ molecule has one end that is slightly negative and one end that is slightly positive although the overall molecule is neutral.
5. In a(n) _________________ molecule, electrons are shared equally.
Section 3 Writing Formulas and Naming Compounds
A. Chemists use ________________ from the periodic table to write formulas for compounds.
B. ________________________—composed of two elements
1. _________________________—how many electrons an atom has gained, lost, or shared to become stable
2. Use oxidation numbers and their least common multiples to write _________________.
a. When writing formulas, remember that the compound is ________________.
b. A formula must have the correct number of positive and negative ions so
the charges ________________.
3. Use the name of the first element, the root name of the second element, and the suffix –ide to write the _____________ of a binary ionic compound.
C. _______________________—positively or negatively charged, covalently bonded group of atoms
1. The compound contains ______________ or more elements.
2. To write names, write the name of the _________________ ion first; then write the name of the _________________ ion.
3. To write _________________, use the oxidation numbers, their least common multiple, and put parentheses around the polyatomic ion before adding a subscript.
D. ________________—compound with water chemically attached to its ions
E. Name binary covalent compounds by using _________________ to indicate how many atoms of each element are in the compound.
CH 21 ORGANIC COMOPUNDS
W Section 1 Simple Organic Compounds
A. Organic compounds—compounds mostly found in living things and containing the element __________
B. Carbon can form many _____________________ because:
1. It has ________ electrons in its outer energy level, so it can form ________ covalent bonds with atoms of carbon or other elements.
2. It can link together with other __________ atoms in many different arrangements, like chains, branched chains, or rings.
3. It can form single, double, or triple _________.
4. It can bond with atoms of other ____________, such as hydrogen and oxygen.
C. Hydrocarbon—a compound made up of only __________ and ____________ atoms
1. Many, many different compounds
2. Hydrocarbons produce more than 90 percent of the __________ humans use.
3. Examples:
a. ___________, CH4 , which is the chemical name for natural gas
b. ___________, C3 H8 , which is used in outdoor grills and heaters in hot air balloons
D. Single bonds
1. Saturated hydrocarbons—hydrocarbons that contain only _________________ carbon atoms
a. Holds as many ____________ atoms as possible
b. Examples: methane, ethane, propane, butane
c. Boiling point _____________ with addition of carbon atoms
2. Structural isomers—compounds that have _____________ chemical formulas but_____________ molecular structures and shapes
a. The ______________ of isomers can vary a lot.
b. Generally, melting points and boiling points ____________ with more branching in the isomer.
E. Multiple bonds
1. Unsaturated hydrocarbons—hydrocarbons that contain at least one __________ or__________
2. Example of double bond
a. ____________, C2 H4; also called __________
b. Two carbon atoms share _______ electrons
3. Example of triple bond
a. __________
b. Two carbon atoms share _________ electrons
4. Polyunsaturated hydrocarbons have _________________ double or triple bond.
CH 9 RADIOACTIVITY AND NUCLEAR REACTIONS
Section 1 Radioactivity
A. The ________________ of an atom is composed of protons and neutrons, which comprise most of the atom’s mass.
B. The ______________________ causes protons and neutrons to be attracted to each other in the nucleus
1. The strong force is powerful only when neutrons and protons
Are ________________________________________?
2. The protons and neutrons in a ______________ nucleus are held less tightly by the strong force than protons and neutrons in a ______________ nucleus.
C. ______________________—Nuclear decay that happens when the strong force is not large enough to hold the nucleus together; the nucleus gives off matter and energy.
1. _________________ Are atoms of the same element with varying numbers of neutrons.
2. A nucleus with too many or too few neutrons compared to ________________ is radioactive.
Section 2 Nuclear Decay
F. The __________________ of a radioactive isotope is the length of time it takes half the nucleus to decay; half-lives vary from fractions of a second to billions of years.
G. Carbon dating can be used to date once-living materials while ________________ dating can be used to date rocks.
Section 4 Nuclear Reactions
A. Nuclear ________________—process of splitting a nucleus into two nuclei with smaller masses; a large amount of energy is released.
1. _______________________—an ongoing series of fission reactions
2. ______________________—amount of fissionable material required to continue a reaction at a constant rate
B. Nuclear _______________—two nuclei with low masses are combined to form one nucleus of larger mass.
1. Nuclear fusion can happen only when nuclei are moving fast enough to get ______________to each other.
2. _____________________ in stars (millions of degrees Celsius) are high enough for fusion to occur.
C. Nuclear __________________ have medical uses.
1. Radioisotopes are used as ________________ to find or keep track of molecules in an organism.
2. _______________ cells can be killed with carefully measured doses of radiation.
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Unit 4 notes
CHAPTER 24 Chemical Reactions
Section 1 Chemical Changes
A. Describing ______________________—change of one or more substances converted into new
substances
1. _____________ are substances that combine or change.
2. New substances that are produced are called ____________.
B. ________________________—a law which states that, in a chemical reaction, matter is not
created or destroyed; it stays the same.
1. _____________________—experimented with mercury (II) oxide and heat
2. Found mass of products (liquid mercury and oxygen gas) ___________ mass of reactants
C. Writing equations—a _____________________ uses chemical formulas and symbols to
describe a chemical reaction and the product(s) it produces.
1. Chemical formula expresses the relationship between elements in the compounds and
molecules they make up
2. ________________—numbers which represent the number of units of each substance in a
reaction
3. Knowing coefficients of chemical reactions allows chemists to use the
___________________ of reactants to predict the amounts of products.
4. Subscripts—numbers which represent the number of _________ in a molecule of a particular
element.
5. Symbols used to show state of reactants: (s)_____, (aq)_______, (g)___, (clear)______.
D. __________ react with atmosphere in different ways.
Section 2 Chemical Equations
A. Checking for ___________—law of conservation of mass requirement
1. A ____________ chemical reaction—both sides of equation have same number of atoms
of each element
2. Choosing coefficients— becomes easier with practice; trial and error at first
WoB. ___________ balanced chemical equations—a four-step process
1. Describe the reaction in _________.
2. Write the ____________ using formulas and symbols.
3. Check for ___________.
4. Add ________________ where needed for balance.
Section 3 Classifying Chemical Reactions
A. _____________ reaction—two or more substance form a new substance; A + B ¿C
B. One substance breaks down into two or more substances in a __________________ reaction;
AB ¿A + B
C. _______________________ reaction—one element replaces another one in a compound;
A + BC ¿AC + B or D + BC ¿BD + C
D. A _______________________ reaction results if a precipitate, water, or a gas forms when two
ionic compounds in solution are combined; AB + CD ¿AD + CB
Section 4 Chemical Reactions and Energy
A. Chemical reactions involve energy ____________.
1. Breaking chemical bonds ____________ energy.
2. ___________ chemical bonds releases energy.
B. More energy ________
1. _______________________—energy required to break bonds is less than the energy
released from new bonds; energy given off is usually light.
2. ______________ reactions—energy given off in the form of heat
C. More energy ______
1. ______________ reactions—more energy is required to break bonds than to form new
ones; need energy for the reaction to occur
2. If energy needed is heat, the reaction is _______________.
3. A ____________ speeds up a chemical reaction without itself being permanently changed.
4. An _____________ prevents or slows a chemical reaction or interferes with a catalyst’s action.rksheet
CHAPTER 25 Acids,Bases,and Salts
Section 1 Acids and Bases
A. ________—contains at least one ____________ atom that can be removed when the acid is
dissolved in water, forming _____________ ions
B. ______________ of acids
1. Taste ________
2. _____________ and can damage skin or tissue
3. React with an _____________ such as __________ paper to produce a predictable color change
C. Common acids
1. Foods contain _________.
a. Citrus fruits have _______________.
b. Yogurt and buttermilk have _______________.
c. Vinegar, or _______________, is in pickled foods.
2. The stomach uses _____________________.
3. Four acids are vital to ____________.
a. _________________ is used in car _____________ and the manufacturing
of _______________.
b. ___________________ is used to manufacture ______________, fertilizers, and
________ drinks.
c. _______________ is used to manufacture _______________ and explosives.
d. Steel can be cleaned with _____________________.
D. ________—a substance that forms _____________ ions in a water solution; also accepts
_____________ ions from acids
E. ______________ of bases
1. Many are ______________________ in pure undissolved state.
2. Feel ____________ in solution
3. Strong bases are ______________.
4. React with ______________ to produce predictable _________ changes; litmus paper
turns ________rksheet
F. Common bases are used in _____________________, medications, fabrics, and deodorants.
G. _____________ of acids and bases
1. Acid describes compounds that can be ___________ in water to form _____________ ions.
2. Base describes compounds that can form _____________ ions in solution.
3. Solutions of acids and solutions of bases are _______________________ to some extent.
Section 2 Strength of Acids and Bases
A. The strength of an acid or base depends on how completely a compound separates into ions
when dissolved in _________.
1. A _______________ ionizes almost completely in solution.
2. A _____________ only partly ionizes in solution.
3. A _______________ dissociates completely in solution.
4. A _____________ does not dissociate completely.
5. Strong acids and bases conduct ________ electricity than weak ones.
6. Equations for strong acids and bases use a __________ arrow, indicating ions are formed.
7. Equations for weak acids and bases use __________ arrows pointing in opposite directions,
indicating an incomplete reaction.
8. __________ and ________________ are terms to describe the amount of acid or base dissolved.
B. pH of a _____________
1. ______ is a measure of the concentration of ___________ in a solution or how acidic or
basic it is.
a. pH lower than 7 means ___________.
b. pH greater than 7 means _________.
c. pH exactly 7 indicates a ___________ solution.
2. pH is determined using a _______________________ paper or a pH _________ .
3. Blood contains ___________ which keep the pH in the blood balanced at about 7.4.
Section 3 Salts
A. __________________—chemical reaction between an acid and a base taking place in a
water solution
B. ________—compound formed when the ____________ ions from an acid combine with the
____________ ions from a base; salts also form when _________ react with metals
1. Salts are essential for many ___________.
2. Other salt ________ include manufacturing of paint, rubber, glass, soap, detergents, and
____________ batteries.
C. Titration is used to determine the _________________ of an acidic or basic solution.
1. A solution of known concentration is the ____________ solution.
2. An acid/base _____________ is added to the ___________ solution.
3. A color change that persists is the _______ point.
D. _________ are organic salts with polar and ____________ ends.
1. The nonpolar, _______________ end interacts with _______ and ________.
2. The polar end helps oil and dirt ____________ in water.
E. ______________—form more ___________ salts with the ________ in hard water and reduce
soap scum; can cause other _________________ problems
F. __________—come from ____________ that are not bases but have a ____________ group
1. Esters are used in ____________________ and perfumes.
2. Polyesters are ____________________ used to make fabrics.
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Unit 5
Motion and Speed Chapter2
Section 1 Describing Motion
A. __________—when an object changes its position relative to a reference point
1. ____________—how far an object has moved
2. ________________—distance and direction of an object’s change in position from the starting point
B. _________—distance an object travels per unit of time
1. ________—any change over time
2. Calculation for speed: speed = distance / ________
3. Speed that doesn’t change over time—_____________ speed
4. Speed is usually not constant; usually an object has ____________ speed.
5. _________________—speed of motion when speed is changing: speed = total ____________ / total travel time
6. _______________________—speed at any given point in time
C. A distance-time _________ displays motion of an object over time.
1. Plot distance on a(n) ____________ axis.
2. Plot time on a(n) ______________ axis.
D. ____________—speed and direction of an object’s motion
E. Motion of Earth’s crust—so ________ we don’t notice
Section 2 Acceleration
A. ________________—change in velocity’s rate
1. ____________ acceleration—speed is increasing.
2. ____________ acceleration—speed is decreasing.
3. When an object changes speed or _____________, it is accelerating.
B. Calculating acceleration
1. Acceleration = ______________________ / time
2. Change in velocity = __________________ – initial velocity
3. Unit for acceleration—meters per __________ squared
4. Positive acceleration—positive number with a ____________ slope on a velocity-time graph.
5. Negative acceleration—negative number with a ____________ slope on a velocity-time graph
C. Amusement park acceleration—Roller coasters
1. Changes in _________ cause acceleration.
2. Changes in _____________ cause acceleration.
Section 3 Motion and Forces
A. _________—a push or pull that one body applies to another
1. A force can cause an object’s __________ to change.
2. When two or more forces combine at the same time, they create a _____________.
3. Balanced forces are equal in ________ and opposite in _____________.
4. _____________________ are unequal in size and / or are in the same direction.
B. Inertia and Mass
1. ___________—an object’s resistance to any change in motion
2. Objects with greater ________ have greater inertia.
3. Newton’s _______________________—an object moving at a constant velocity keeps moving at that velocity unless a net force acts on it; an object at rest will stay at rest unless a net force acts on it.
C. Auto crashes—the law of ___________ at work
1. A passenger not wearing a seat belt keeps moving ___________ at the car’s speed even after the car stops.
2. A passenger wearing a seat belt ______________ as the car slows down and stops.
Forces (chapter 3)
Section 1 Newton ’s Second Law
A. Force and motion are ___________________.
1. An object will have greater ______________________ if a greater force is applied to it.
2. The ______________ of an object and the force applied to it affect acceleration.
B. Newton’s second law of motion connects force, mass, and acceleration in the equation acceleration equals net force ______________ by mass.
C. __________________—force that opposes motion between two surfaces that are touching each other
1. ____________________, areas where surface bumpers stick together, are the source of friction.
2. Friction between two surfaces that are not moving past each other is
called ________________ friction.
3. _________________ friction—force that opposes the motion of two surfaces sliding past each other
4. Friction between a rolling object and the surface it rolls on is called _________________
friction.
D. ________________________ that opposes the force of gravity
1. The ________________ of air resistance depends on an object’s shape, size, and speed.
2. ___________________________—forces on a falling object are balanced and the object falls with constant speed
Section 2 Gravity
A. Law of ____________________—any two masses exert an attractive force on each other
1. _________________ is one of the four basic forces that also include the electromagnetic force, the strong nuclear force, and the weak nuclear force.
2. Gravity is a ____________________ force that gives the universe its structure.
B. Due to _________________, all objects fall with the same acceleration regardless of mass.
C. ________________—gravitational force exerted on an object
1. Weight ___________________ as an object moves away from Earth.
2. Weight results from a force; ______________ is a measure of how much matter an object contains.
D. Objects in the space shuttle _______________ because they have no force supporting them.
E. _____________________ have horizontal and vertical velocities due to gravity, and follow a curved path.
F. Acceleration toward the center of a curved path is called centripetal acceleration; it is caused by centripetal _______________, an unbalanced force.
Section 3 The Third Law of Motion
A. Newton’s third law of motion—to every action force there is an equal
and ___________________ reaction force
1. Action-reaction forces act on ___________________ objects and differ from balanced forces.
2. ___________________________ is based on Newton’s third law of motion.
B. Before it was discovered, the existence of the planet _________________ was predicted based on gravitational forces and Newton’s laws.
C. __________________—related to how much force is needed to change an object’s motion; momentum equals mass times velocity.
D. Law of conservation of momentum—momentum can be ___________________ between
objects; momentum is not lost or gained in the transfer.taking
Worksheet
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Unit 6 notes
Energy ch 4
Section 1 The Nature of Energy
A. Energy is the ability to cause ___________.
1. Kinetic energy—Energy in the form of ____________.
a. The amount of kinetic energy an object has depends on its _________ and its
___________.
b. Kinetic energy = 1/2 ________ .velocity 2
c. __________—The SI unit used to measure energy
2. Potential energy—Energy stored in a ______________ object, giving it the potential to
cause change
3. Elastic potential energy—Energy stored by things that ___________________.
4. Chemical potential energy—Energy stored in __________________ between atoms
5. Gravitational potential energy—Energy stored by things that are
_________________________ .
a. The amount of GPE an object has depends on its ___________ , the acceleration
due to _______ , and its _____________________.
b. GPE = mass in kilograms .9.8 m/s 2 .height in __________
Section 2 Conservation of Energy
A. Energy conversions—energy changing from one _________ to another
1. Fuels store energy in the form of _______________________ energy.
2. ______________ energy—the total amount of potential and kinetic energy in a system
B. Law of Conservation of Energy—Energy may change from one form to another, but the
________________ of energy never changes.
1. Example—As a swing moves back and forth, its energy continually converts from
____________ to _____________ and back.
2. If the energy of the swing decreases, then the energy of some other object must
____________ by an equal amount.
3. Friction converts some of the mechanical energy into ___________ energy.
C. Converting _________ into energy—You must think of mass as energy when discussing
nuclear reactions. The total amount of mass and energy is conserved.
1. Nuclear _______________—Two nuclei are fused together. Takes place in the sun.
2. Nuclear fission—Two nuclei are ______________________.
D. Conservation of energy in your body
1. _____________________ energy from food that is stored in your body is used to fuel the
processes that keep you alive.
2. The food _____________ is used to measure how much energy you get from various foods.
One Calorie is equivalent to about 4,180 J.Worksheet
Work and Machines ch 5
Section 1 Work
A. ______________—transfer of energy that occurs when a force makes an object move
1. For work to occur, an object must ______________.
2. The motion of the object must be in the ________________________ as the applied force on the object.
B. Work and energy are related, since energy is always _____________________ from the object doing the work to the object on which the work is done.
C. Work is done on an object only when a _______________ is being applied to the object and the object moves.
D. Calculating work—work equals force (in newtons) times __________________
E. _______________—amount of work done in a certain amount of time; rate at which work is done
1. ___________________________—power equals work divided by time.
2. Power is measured in _______________ (W).
3. Since work and energy are _________________, power also can be calculated—power equals energy divided by time.
Section 2 Using Machines
A. Device that makes doing work easier is a _________________.
B. Machines __________________ applied force and/or ________________ direction of applied force to make work easier.
1. Same amount of work can be done by applying a small force over a long distance as can be done applying a large force over a short distance, since work equals _______________ times __________________.
2. Increasing __________________ reduces the amount of force needed to do the work.
3. Some machines change the ___________________ of the applied force to do the work.
C. Machines help move things that ________________ being moved.
1. Force applied to machine is ______________________.
2. __________________________—force applied by machine to overcome resistance
3. Amount of energy the machine transfers to the object cannot be _________________ than
the amount of energy transferred to the machine.
a. Some energy transferred is changed to ______________ due to friction.
b. An ideal machine with no __________________ would have the same input work and
output work.
D. ______________________________ (MA) is the number of times a machine multiplies the
effort force. It is calculated by MA equals resistance force divided by effort force.
E. ____________________—measure of how much of the work put into a machine is changed
into useful output work by the machine
1. _____________________ efficiency—efficiency equals (output work divided by input work)
times 100%.
2. Efficiency of a machine is always ______________ than 100%.
3. ____________________ can make machines more efficient by reducing friction.
Section 3 Simple Machines
A. A machine that does work with only one movement is a ________________________.
B. _______________—bar that is free to pivot about a fixed point called the fulcrum
1. ________________ arm is part of the lever on which effort force is applied.
2. ____________________ arm is part of the lever that exerts the resistance force.
3. Three classes of levers based on ___________________ of effort force, resistance force, and fulcrum
a. _____________________ lever—fulcrum is located between the effort and resistance forces; multiplies and changes direction of force
b. ______________________ lever—resistance force is located between the effort force and fulcrum; always multiplies force
c. _____________________ lever—effort force is between the resistance force and fulcrum; doesn’t multiply force but does increase distance over which force is applied
4. Calculating ideal mechanical advantage (IMA) of a lever—IMA equals length of ________________ arm divided by length of resistance armWorksheet
C. Grooved wheel with a rope, simple chain, or cable running along the groove is a
________________, which is a modified first-class lever.
1. A _______________ pulley is attached to something that doesn’t move; force is not multiplied
but direction is changed; IMA = 1.
2. A _________________ pulley has one end of the rope fixed and the wheel free to move;
multiplies force; IMA = 2.
3. __________________________—system of pulleys consisting of fixed and movable pulleys;
IMA = number of ropes supporting resistance weight
D. ________________________—machine with two wheels of different sizes rotating together;
modified lever form
1. IMA = radius of wheel _________________ by the radius of axle
2. _______________ are a modified form of the wheel and axle.
E. ________________________—sloping surface that reduces the amount of force required to
do work
1. IMA = length of slope (effort distance) _________________ by height of slope (resistance
distance)
2. Less force is required if a ramp is longer and less steep.
F. _______________—inclined plane wrapped in a spiral around a cylindrical post
G. Inclined plane with one or two sloping sides is a _______________.
H. __________________________—uses a combination of two or more simple machines
Waves ch 11
Section 1 The Nature of Waves
A. Wave—a repeating disturbance or movement that transfers __________ through matter or space
1. Molecules pass energy on to _______________ molecules.
2. Waves carry energy without transporting __________.
3. All waves are produced by something that ____________.
4. Medium—a ____________ through which a wave travels.
a. May be solid, liquid, or ________
b. Not all waves need a medium to travel through; example: _______________
B. Mechanical waves—waves that can travel only through __________
1. Transverse waves—matter in the medium moves back and forth _____________________
the direction that the wave travels; example: _______________
2. Compressional waves—matter in the medium moves _________________________ that
the wave travels; example: _______________
3. Combinations—not purely transverse or compressional; examples: water waves,
___________ waves
Section 2 Wave Properties
A. Ways waves differ
1. How much __________ they carry
2. How ________ they travel
3. How they look
a. ______________ waves have crests—the highest points, and troughs—the lowest points.
b. Compressional waves have dense regions called ________________ and less dense
regions called ________________.
B. Wavelength—the distance between one point in the wave and
___________________________________
C. Frequency—how many _______________ pass a fixed point each second
1. Expressed in _______________
2. As frequency increases, wavelength ______________.
3. The frequency of a wave equals the rate of _____________ of the source that creates it.
D. Wave ____________, or v, describes how fast the wave moves forward.
1. ____________ = wavelength ._____________, or v = ¿¿.f.
2. Light waves travel __________ than sound waves.
3. Sound waves travel faster in ___________ and __________ than in gas.
4. Light waves travel faster in _________ and _______________ than in liquids and solids.
E. Amplitude—a measure of the __________ in a wave
1. The more energy a wave carries, the ___________ its amplitude.
2. Amplitude of _________________ waves is related to how tightly the medium is pushed
together at the compression.
a. The __________ the compressions, the larger the amplitude is and the more energy the
wave carries.
b. The less dense the rarefactions, the __________ the amplitude and the more energy the
wave carries.
3. Amplitude of ______________ waves
a. The distance from the crest or trough of a wave to the ____________________of the
medium
b. Example: how high an ocean wave appears above the water level
Section 3 The Behavior of Waves
A. Reflection occurs when a wave strikes an object and _______________ of it.
1. _______ types of waves can be reflected.
2. The angle of incidence of a wave is always equal to the angle of ________________.
a. Normal—an imaginary line _________________ to a reflective surface
b. Angle of _____________—the angle formed by the wave striking the surface and the
normal
c. Angle of ______________—the angle formed by the reflected wave and the normal
B. Refraction—the ___________ of a wave caused by a change in its speed as it moves from one
medium to another
1. The greater the change in speed is, the ________ the wave bends.
2. When a wave passes into a material that slows it down, the wave is bent __________ the
normal.
3. When a wave passes into a material that speeds it up, the wave is bent _____________ the
normal.
C. Diffraction—an object causes a wave to change direction and ________ around it
1. If the obstacle is ___________ than the wavelength, the wave diffracts a lot.
2. If the obstacle is much __________ than the wavelength, the wave does not diffract much.
3. The larger the obstacle is compared to the wavelength, the ________ the waves will diffract.
D. Interference—the ability of two or more waves to ___________ and form a new wave
1. Waves pass right through each other and continue in ____________________________.
2. New wave exists only while the two original waves continue to ___________.
3. Constructive interference—waves _______ together
4. Destructive interference—waves ____________ from each other
E. Standing waves—a wave pattern that stays in ______________
1. Form when waves of equal ______________ and amplitude that are traveling in
____________ directions continuously interfere with each other
2. Nodes—the places where two waves __________ cancel each other
F. Resonance—the ability of an object to ___________ by absorbing energy at its natural frequency
Sound ch 12
Section 1 The Nature of Sound
A. All sounds are caused by something that ______________.
1. _______________—formed when a vibrating object collides with air molecules,
transferring energy to them
2. Compressional waves have two regions, called compressions and ________________, which
push air molecules together and then spread them apart.
B. __________—the type of matter, whether liquid, solid, or gas; that sound waves travel through
1. A sound wave’s _________ depends on the substance of the medium and whether the
medium is solid, liquid, or gas.
2. Sound travels more ___________ through solids and liquids because the individual
molecules are closer together than the molecules in gas.
3. As a medium’s _______________ increases, its molecules move faster and it conducts
sound waves faster.
C. Human hearing—________ stages
1. The outer ear gathers sound waves, passing them through the ear canal to a tough
membrane called the ____________
2. The vibrating eardrum passes the sound to three tiny bones in the middle ear—the
__________, _________, and ___________—which amplify the sound wave.
3. The stirrup vibrates and transfers the sound to a membrane in the oval window, then on to
the inner ear’s ___________, a spiral-shaped structure that contains hair cells.
4. As the hair cells in the cochlea vibrate, nerve impulses are sent through the ____________
nerve to the brain.
Section 2 Properties of Sound
A. The amount of energy a wave carries corresponds to its _____________, which is related to the
density of the particles in the compressions and rarefactions.
1. _____________—the amount of energy that flows through a certain area in a specific
amount of time
2. ____________—human perception of sound intensity
3. Each unit on a scale that measures sound intensity is a _____________.
hB. _________—how low or high a sound seems to be
1. _____________ is the number of compressions or rarefactions of a sound wave that
pass per second; human ears can hear frequencies from about 20 to 20,000 Hz.
2. ______________ waves are sound frequencies over 20,000 Hz that have medical
and scientific uses.
3. Infrasonic or ____________ waves with frequencies below 20 Hz usually can’t be
heard but may feel like a rumble.
C. __________________—change in pitch or wave frequency due to a moving; either
the source of the wave or the observer can be moving
Section 3 Music
A. _________—sounds that are deliberately used in a regular pattern
1. _____________________—frequency at which the a material vibrates
2. _____________—the ability of a medium to vibrate by absorbing energy at its own
natural frequency
B. Sound ___________—the differences among sounds of the same pitch and loudness
1. _________________________—the main tone played and heard
2. ____________—vibration with a frequency that is a multiple of the fundamental frequency
C. Musical instruments—___________ used to make musical sounds
1. ___________—instruments in which sound is produced by plucking, striking, or
drawing a bow across tightly stretched strings
2. Brass and woodwinds—air vibration in a _____________, or hollow chamber that
amplifies sound, with the pitch determined by the length of the vibrating tube of air
3. ______________ instruments produce sound by being struck, shaken, rubbed, or brushed.
D. _________—a pulsing vibration in loudness
Section 4 Using Sound
A. Uses of sound—_________________, warning signals, information
B. _____________—study of sound, which can prevent excessive reverberation and create
good listening environments
C. ________________—process of locating objects by sending out sounds and interpreting
the waves reflected back
D. _________—a system that uses the reflection of underwater sound waves to locate objects
E. ______________ waves are used in medicine to diagnose, monitor, and treat many conditions.
1. Can produce images of ____________ structures for detection of medical problems
2. Can _________ certain medical problems such as kidney stones or gallstones
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unit 7
Electricity
Section 1 Electric Charge
A. Protons have positive electric charge; electrons have negative
electric charge.
1. In most atoms, the charges of the protons and electrons cancel each other out and the atom has no net charge.
2. Atoms become charged by gaining or losing electrons.
3. Static electricity—the accumulation of excess electric charges on an object
B. Electrically charged objects obey the following rules:
1. Law of conservation of charge—charge may be transferred from object to object, but it cannot be created or destroyed
2. Opposite charges attract, and like charges repel.
3. Charges can act on each other even at a distance, because any charge that is placed in an electric field will be pushed or pulled by the field.
4. Electrons move more easily through conductors, like metals.
5. Electrons do not move easily through insulators, such as plastic, wood, rubber, and glass.
C. Transferring electric charge
1. Charging by contact
a. The process of transferring charge by touching or rubbing
b. Example: static electricity from your feet rubbing the carpet
2. Charging by induction
a. The rearrangement of electrons on a neutral object caused by a nearby charged object
b. Example: a negatively charged balloon near your sleeve causes an area of your sleeve to become positively charged
3. Static discharge
a. A transfer of charge through the air between two objects because of a buildup of static electricity
b. Example: lightning
4. Grounding—using a conductor to direct an electric charge into the ground
D. The presence of electric charges can be detected by an electroscope.
TSection 2 Electric Current
A. The flow of charges through a wire or conductor is called electric current.
1. Current is usually the flow of electrons.
2. Electric current is measured in amperes (A).
3. Charges flow from high voltage to low voltage.
a. A voltage difference is the push that causes charges to move.
b. Voltage difference is measured in volts (V).
4. For charges to flow, the wire must always be connected in a closed path, or circuit.
B. Sources of electricity:
1. A dry cell battery produces a voltage difference between its zinc container and its carbon suspension rod, causing current to flow between them.
2. A wet cell battery contains two connected plates made of different metals in a conducting solution.
3. Wall sockets have a voltage difference across the two holes of an electrical outlet, and a generator at a power plant provides this voltage difference.
C. Resistance—the tendency for a material to oppose the flow of electrons, changing electrical energy into thermal energy and light
1. All materials have some electrical resistance.
2. Resistance is measured in ohms ¿¿¿¿¿).
3. Making wires thinner, longer, or hotter increases the resistance.
D. Ohm’s law—the current in a circuit equals the voltage difference divided by the resistance
Section 3Electrical Circuits
A. Circuits rely on generators at power plants to produce a voltage difference across the outlet, causing the charge to move when the circuit is complete.
1. Series circuit—the current has only one loop to flow through
a. The parts of a series circuit are wired one after another, so the amount of current is the same through every part.
b. Open circuit—if any part of a series circuit is disconnected, no current flows through the circuit
c. Example: strings of holiday lights
2. Parallel circuit—contains two or more branches for current to move through
a. Individual parts can be turned off without affecting the entire circuit.
b. Example: the electrical system in a house
B. Household circuits use parallel circuits connected in a logical network.
1. Each branch receives the standard voltage difference from the electric company.
2. Electrical energy enters your home at the circuit breaker or fuse box and branches out to wall sockets, major appliances, and lights.
3. Guards against overheating electric wires:
a. Electric fuse—contains a small piece of metal that melts if the current becomes too high, opening the circuit and stopping the flow of current
b. Circuit breaker—contains a small piece of metal that bends when it gets hot, opening the circuit and stopping the flow of current
C. Electrical energy is easily converted to mechanical, thermal, or light energy.
1. Electrical power—the rate at which electrical energy is converted to another form of energy
a. Electrical power is expressed in watts (W).
b. Power = current .voltage difference
c. P (watts) = I (amperes) .V (volts)
2. To calculate the amount of energy an appliance uses:
a. The unit of electrical energy is the kilowatt-hour, which equals 1000 watts of power used for one hour.
b. Energy = power .time
c. E (kWh) = P (kW) .t(h)ontent Outline for Teaching (continued)
Magnetism and Its Uses
Section 1 Magnetism
A. Magnetism—the properties and interactions of magnets
1. Interaction between two magnets called magnetic force increases
as magnets move closer together.
2. A magnetic field, which exerts the magnetic force, surrounds a magnet, and is strongest closest to the magnet.
B. Magnetic poles—the regions of a magnet where the magnetic force exerted by the magnet is strongest
1. All magnets have a north pole and a south pole.
2. Like poles attract. Unlike poles repel.
3. Earth has magnetic poles.
a. A compass needle is a small bar magnet that can freely rotate.
b. A compass needle always points north.
C. Magnetic materials—iron, cobalt, and nickel
1. The magnetic field created by each atom exerts a force on nearby atoms.
2. Magnetic domains—groups of atoms with aligned magnetic poles
a. In a magnet, the like poles of all the domains point in the same direction.
b. Permanent magnets are made by placing a magnetic material in a strong magnetic field, forcing a large number of magnetic domains to line up.
Section 2 Electricity and Magnetism
A. Moving charges and magnetic fields
1. Moving charges, like those in an electric current, produce magnetic fields.
a. The magnetic field around a current-carrying wire forms a circular pattern about the wire.
b. The direction of the field depends on the direction of the current.
c. The strength of the magnetic field depends on the amount of current flowing in the wire.
B. Electromagnet—a temporary magnet made by placing a piece of iron inside a current-carrying coil of wire
1. Magnetic field is present only when current is flowing in the wire coil.
2. Increase strength of the magnetic field by adding more turns to the wire coil or increasing the current passing through the wire.
3. Magnetic properties of electromagnets can be controlled by changing the electric current flowing through the wire coil.
4. Converts electrical energy into mechanical energy to do work
C. Galvanometer—a device that uses an electromagnet to measure electric current
D. Electric Motor—a device that changes electrical energy into mechanical energy
1. Contains an electromagnet that is free to rotate between the poles of a permanent, fixed
magnet. The coil in the electromagnet is connected to a source of electric current.
2. When a current flows through the electromagnet, a magnetic field is produced in the coil.
3. Changing the direction of the current causes the coil in an electric motor to keep rotating.
4. Rotation speed of electric motors can be controlled.
a. Vary the amount of current flowing through the coil.
b. When more current flows through the coil, the electromagnet’s magnetic field becomes
stronger, the magnetic force between the coil and the permanent magnet increases, and
the coil turns faster.
SSection 3 Producing Electric Current
A. From mechanical to electrical energy
1. Electromagnetic induction—the production of an electric current by moving a loop of
wire through a magnetic field or moving a magnet through a wire loop
2. Generator—a device that produces electric current by rotating a coil of wire in a magnetic field
a. The wire coil is wrapped around an iron core and placed between the poles of a
permanent magnet.
b. Coil is rotated by an outside source of mechanical energy.
c. As the coil turns within the magnetic field of the permanent magnet, an electric current
flows through the coil.
d. Direction of the current in the coil in a generator changes twice with each revolution.
3. Generating electricity
a. Electricity used in the home comes from a power plant with huge generators.
b. Coils of electromagnets in the generators usually connected to a turbine—a large wheel
that rotates when pushed by water, wind, or steam.
B. Direct and alternating currents
1. Direct current (DC) is current that flows in only one direction through a wire.
2. Alternating current (AC) reverses the direction of the current flow in a regular way.
a. In North America, generators produce alternating current at a frequency of
60 cycles per second, or 60 Hz.
b. A 60-Hz alternating current changes direction 120 times each second.
C. Transformer—a device that increases or decreases the voltage of an alternating current
1. Made of two coils (primary and secondary) wrapped around the same iron core.
2. Changing current in primary coil creates changing magnetic field around the iron core,
which induces an alternating current in the secondary coil.
3. A step-up transformer increases voltage. The secondary coil has more turns of wire than the primary coil does.
4. A step-down transformer decreases voltage. The secondary coil has fewer turns of wire than the primary coil does.
5. Power carried in power lines as high as 750,000 V is reduced by step-down transformers to
household current (AC) of 120 V.