Chapter 2: Properties of Matter
2.1 Classifying Matter
Each piece of your clothing has a label that recommends cleaning methods. A 100%-cotton shirt
may need to be ironed after washing. A cotton and polyester blend fabric may come out of the
dryer wrinkle free. There is no cleaning process that works for all materials.
Why are elements and compounds classified as pure substances?
A pure substance is _______________________________________________________________________________________
•Table salt and table sugar are two examples of pure substances.
•Substances can be classified into two categories—_____________________________________________________.
Every sample of a given substance has the same properties because a substance has ________
________________________________________________________________________________________________________________
How do mixtures differ from pure substances?
An element is a _____________________________________________________________________________________________
An element has a fixed composition because it contains ____________________________________________.
No two elements contain the same type of atom
Examples of Elements
•Some elements are solids at room temperature. Most soft drink cans are made from aluminum.
Carbon is the main element in the marks you make with a pencil.
•The elements oxygen and nitrogen are the main gases in the air you breathe.
•Two elements are liquids at room temperature–bromine and mercury.
Symbols for Elements
Chemists use symbols of ____________________________________________ to represent elements. _____________
_________________________________________________________________________________________________________________
•_______ represents carbon.
•_______ represents aluminum.
•_______ represents gold. (The Latin name for gold is aurum.)
Symbols for Elements
Symbols allow scientists who speak different languages to _______________________________________________
____________________________________. For example, nitrogen is azote in France, stickstoff in Germany, and
nitrógeno in Mexico. But all scientists use _______ as the symbol for the element ________________________
Aluminum, carbon, and gold are elements that you can see in common objects, such as cans, pencils,
and rings. Mixtures containing iodine are used to prevent and treat infections.
How do mixtures differ from pure substances?
A compound is a substance that is ________________________________________________________________________
__________________________________________________________________________________________________________________
A compound always contains _____________________________________________________________________________.
Chapter 2: Properties of Matter
The properties of a compound ___________________ from those of the substances from which it is made.
•____________ is composed of the elements _____________________________________________________. Oxygen and
hydrogen are _______________ at room temperature, but water is a ______________________.
•Hydrogen can fuel a fire, and oxygen can keep a fire burning, but water does not burn or help other
substances to burn.
Silicon dioxide is a compound found in most light-colored grains of sand and in crystals of quartz. It
is a colorless, transparent solid. Yet, silicon dioxide is made from a colorless gas (oxygen) and a gray
solid (silicon). In silicon dioxide, there are always two oxygen atoms for each silicon atom.
How do mixtures differ from pure substances?
If you make salsa, a recipe can guide you. You can use exactly the amounts in the recipe, or you can
adjust the ingredients to your own taste. Salsa is a mixture. _____________________________________________
_________________________________________________________________________________________________________________
The properties of a mixture can vary because _________________________________________________________
_________________________________________________________________________________________________________________
•Mixtures can retain ________________________________________________________________________________ of their
individual substances.
•The properties of a mixture are ____________________________________ than the properties of a substance.
Mixtures can be classified by how well the parts of the mixture are distributed throughout the
mixture.
Heterogeneous Mixtures
In a heterogeneous mixture, _______________________________________________________________________________
__________________________________________________________________________________________________________________
Homogeneous Mixtures
In a homogeneous mixture, ________________________________________________________________________________
__________________________________________________________________________________________________________________
The sand is a heterogeneous mixture of different kinds of grains. The spoon is stainless steel, a
homogeneous mixture of iron, chromium, and nickel.
Do the Contents of Two Cans of Mixed Nuts Meet FDA Regulations?
According to Food and Drug Administration (FDA) regulations, a can labeled mixed nuts must
contain at least four types of shelled nuts other than peanuts. The mass of each type of nut must be
not less than 2 percent of the total mass and not more than 80 percent of the total mass.
1. Comparing and Contrasting How are the two brands of mixed nuts alike? How are they
different?
2. Calculating What is the percent by mass of each type of nut in each can?
3. Drawing Conclusions Do the contents of each can meet the FDA regulations? Explain.
Chapter 2: Properties of Matter
4. Inferring On the Brand A label, the nuts are listed in this order: peanuts, Brazil nuts, almonds,
cashews, pecans, and hazelnuts. What do you think determines the order?
What is the main difference among solutions, suspensions, and colloids?
The size of the particles in a mixture has an effect on the properties of the mixture.
Based on the size of its ____________________________________________________, a mixture can be classified
as a _____________________________________________________________________________________________________________.
Solutions
When substances dissolve and form a homogeneous mixture, the mixture that forms is called a
__________________________
Suspensions
A suspension _________________________________________________________________________________________________
Colloids
A colloid _______________________________________________________________________________________________________
__________________________________________________________________________________________________________________
•Like solutions, colloids ______________________________________________________________________________________.
•You cannot use a filter to separate the parts of a colloid.
These liquids represent three categories of mixtures.
•Windshield wiper fluid is a __________________________________________.
•Muddy water collected from a swamp is a _______________________________________.
•Milk is a _______________________________.
1.Which of these substances is a compound?
2.Which of these groups of letters could be used as a symbol for an element?
3.Which of the following statements does not apply to a compound?
4.How does a compound differ from a mixture?
5.Which of these materials is a heterogeneous mixture?
6.Which of the following can be separated with a filter?
2.2 Physical Properties
There are pitchers of ice water and lemonade on a picnic table. How do you know which liquid is in
each pitcher? It’s easy! Lemonade is yellow and has a tart taste that is hard to miss. A yellow color
and a tart taste are two properties of lemonade.
What are some examples of physical properties?
Chapter 2: Properties of Matter
A physical property is_______________________________________________________________________________________
__________________________________________________________________________________________________________________
__________________________________________________________________________________________________________________
____________________________________________________________________ are examples of physical properties.
Viscosity
The ____________________________________________________________________________________ is called its viscosity.
•___________________________, such as corn syrup and honey, have a _________________________________________.
•___________________________, such as vinegar and water, have a _____________________________________________.
Conductivity
A material’s __________________________________________________________________________ is called conductivity.
•Materials that have a high conductivity, such as metals, are called ________________________________.
•Good conductors of heat are usually also good conductors of electricity.
Malleability
The ability of ________________________________________________________________________________ is malleability.
•Most metals, such as gold, are malleable.
•An ice cube or piece of glass breaks into small pieces when struck with a hammer. Solids that
shatter when struck are _________________________, not malleable.
Hardness
One material can scratch another material if _______________________________________________________________.
•A kitchen knife can scratch a copper sheet because stainless steel is harder than copper.
•The material used to sharpen the knife blade must be harder than stainless steel.
_____________________ is the hardest known material.
This Tlingit carver is using an adze to carve a canoe from Western red cedar. Red cedar is a
relatively soft wood. The adze is hard.
Melting and Boiling Points
The temperature at which a material changes state is a ______________________________________________
•The temperature at which a ________________________________________________________________________________
_____________________________________________________________.
•The temperature at which a ________________________________________________________________________________
_____________________________________________________________.
Melting and Boiling Points
Which of these substances are liquids at room temperature (20C, or 68F)?
Answer:
Density
The _____________________________________________________________________________________________________________.
•Density can be used to _____________________________________________________________________ of a substance.
•Silver has a density of 10.5 g/cm3. A coin with a density of 9.9 g/cm3 is not made from silver, or it
contains substances in addition to silver.
Chapter 2: Properties of Matter
How can knowing the physical properties of matter be useful?
Physical properties are used to ___________________________________________________________________, to
________________________________________________________________ for a specific purpose, or to ________________
_________________________________________________________________ in a mixture.
Using Properties to Identify Materials
A material _____________________________________________________________________________________________________.
•Decide which properties to test.
•___________________________ on a sample of the _________________________________ material.
•___________________________________________________ with the data reported for ___________________ materials.
Using Properties to Choose Materials
Properties determine which materials are chosen for which uses.
•For example, shoelaces must be flexible, that is they must be able to bend without breaking.
•They must also be durable, that is, they must be able to withstand repeated use.
Laces in hiking boots are usually made of nylon or leather, not from wood.
What processes are used to separate mixtures?
___________________________________________________________________ are two common separation methods.
Filtration
You can separate hot tea from loose tea leaves by pouring the mixture through a strainer. Filtration
is a process that________________________________________________________________________________________________
These students filter (sift) dirt through a wire screen to locate small objects. Particles of dirt are
small enough to pass through the holes, but objects such as broken bits of pottery are too large.
Distillation
Sometimes all the particles in a solution are small enough to pass through a filter. Distillation is a
process that ____________________________________________________________________________________________________
The change of water from a liquid to a gas during boiling is a physical change. A physical change
occurs when ___________________________________________________________________________________________________
__________________________________________________________________________________________________________________
During a physical change, the ________________________________________________________________________________
__________________________________________________________________________________________________________________
Some examples include
•melting butter in a pan
•crumpling a piece of paper
•slicing a tomato
Some but not all physical changes ________________________________________________________________. Braiding
hair is a reversible change. Cutting hair cannot be reversed.
Chapter 2: Properties of Matter
1.Which of the following is not a physical property?
2.Which of these materials is not malleable?
3.In choosing a material for use as a wire to carry electric current, which physical property would
be most important?
4.Which of these statements best describes a physical change in a pure substance?
5.The process of filtration uses the difference in boiling points of substances to separate a mixture.
2.3 Chemical Properties
How would you describe these candles? Color, hardness, and density are physical properties that
you can use in the description. You can also say that the candles are burning. The ability to burn is
not a physical property. As a candle burns, new substances form.
When can chemical properties be observed?
As a candle burns, its compounds combine with oxygen in the air to form water and carbon dioxide.
A chemical property is ______________________________________________________________________________________
__________________________________________________________________________________________________________________
Chemical properties can be observed only ______________________________________________________________
__________________________________________________________________________________________________________________
Flammability
Materials that burn can be used as fuel. Flammability is ________________________________________________
__________________________________________________________________________________________________________________
Reactivity
The property that describes _________________________________________________________________________________
_____________________ is reactivity.
Rust forms _______________________________________________________________. Rust is a brittle, reddish-brown
compound. Because iron is highly reactive, you would not choose iron to make jewelry or coins.
Nitrogen has many uses that depend on its low reactivity.
Researchers in Japan pump nitrogen gas into the steel tanks that hold seawater in ships. The
nitrogen displaces the oxygen dissolved in the water and prevents rusting.
What observations might indicate that a chemical change has occurred?
Three common types of evidence for a chemical change are _________________________________________
__________________________________________________________________________________________________________________
Chapter 2: Properties of Matter
The color change in a banana peel is caused by chemical changes that are taking place in the cells of
the banana. A chemical change occurs _____________________________________________________________________
__________________________________________________________________________________________________________________
A Change in Color
A change in color is ___________________________________________ has produced at least one new substance.
•A shiny silver bracelet that is exposed to air will darken.
•As a match burns, it shrivels up and turns black.
•A new copper roof and an old copper roof have different colors.
A new copper roof has a reddish color.
The green patina on an old copper roof is a mixture of copper compounds.
Production of a Gas
When you mix vinegar with baking soda, bubbles of ______________________________________________________.
A similar chemical change happens when you use baking powder as an ingredient in a cake recipe.
Bubble of carbon dioxide expand and cause the cake to rise.
Formation of a Precipitate
________________________________________________________________________________________________________________ is
called a precipitate. When an acid is added to milk, proteins in the milk undergo a chemical change
that causes them to stick together in clumps and form a precipitate–cottage cheese.
What is the difference between chemical and physical changes?
Are different substances present after a change takes place? If not, then the change is physical, not
chemical.
When matter undergoes a chemical change, ___________________________________________________________
________________________________. When matter undergoes a physical change, ___________________________
_________________________________________________________________________________________
Even if you observe a color change, a gas, or a precipitate, you ___________________________________________
that a chemical change has taken place. When an iron horseshoe is heated, its color changes from
gray to red, but the iron is still iron. That means the change is physical, not chemical.
1.Which of these properties is a chemical property of sulfur?
2.Which of the following is not a common type of evidence for a chemical change?
3.You can be certain that a chemical change has occurred when