Each piece of your clothing has a label that recommends cleaning methods' A 100%cotton shirt may nee

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• 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.

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Pure Substances

• Why are elements and compounds classified as pure
  substances

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Pure Substances

• A pure substance is matter that always has
  exactly the same composition.
• Table salt and table sugar are two examples of
  pure substances.
• Substances can be classified into two
  categorieselements and compounds.

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Pure Substances

• Every sample of a given substance has the same
  properties because a substance has a fixed
  uniform composition.

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Elements

• How do mixtures differ from pure substances
• An element is a substance that cannot be broken
  down into simpler substances.

An element has a fixed composition because it
contains only one type of atom. No two elements
contain the same type of atom.
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Elements

• 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
  temperaturebromine and mercury.

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Elements

• Symbols for Elements
• Chemists use symbols of one or two letters to
  represent elements. The first letter is always
  capitalized. If there is a second letter it is
  not capitalized.
• C represents carbon.
• Al represents aluminum.
• Au represents gold. (The Latin name for gold is
  aurum.)

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Elements

• Symbols for Elements
• Symbols allow scientists who speak different
  languages to communicate without confusion. For
  example nitrogen is azote in France stickstoff
  in Germany and nitrógeno in Mexico. But all
  scientists use N as the symbol for the element
  nitrogen.

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Elements

• 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.

Aluminum
Carbon
Gold
Iodine
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Compounds

• How do mixtures differ from pure substances

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Compounds
A compound is a substance that is made from two
or more simpler substances and can be broken down
into those simpler substances.

• A compound always contains two or more elements
  joined in a fixed proportion.

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Compounds

• The properties of a compound differ from those of
  the substances from which it is made.
• Water is composed of the elements hydrogen and
  oxygen. Oxygen and hydrogen are gases at room
  temperature but water is a liquid.
• Hydrogen can fuel a fire and oxygen can keep a
  fire burning but water does not burn or help
  other substances to burn.

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Compounds

• 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.

Oxygen
Silicon
Silicon dioxide
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Mixtures

• How do mixtures differ from pure substances

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Mixtures

• 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. Each batch may be slightly
  different.

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Mixtures

• The properties of a mixture can vary because the
  composition of a mixture is not fixed.
• Mixtures can retain some of the properties of
  their individual substances.
• The properties of a mixture are less constant
  than the properties of a substance.

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Mixtures

• Mixtures can be classified by how well the parts
  of the mixture are distributed throughout the
  mixture.
• Heterogeneous Mixtures
• In a heterogeneous mixture the parts of the
  mixture are noticeably different from one
  another.
• Homogeneous Mixtures
• In a homogeneous mixture the substances are so
  evenly distributed that it is difficult to
  distinguish one substance in the mixture from
  another.

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Mixtures

• The sand is a heterogeneous mixture of different
  kinds of grains. The spoon is stainless steel a
  homogeneous mixture of iron chromium and
  nickel.

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Mixtures

• 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.

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Mixtures

• Comparing and Contrasting How are the two brands
  of mixed nuts alike How are they different
  Answer

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Mixtures

• Comparing and Contrasting How are the two brands
  of mixed nuts alike How are they different
  Answer Both brands contain the same types of
  nuts but the amount of each type differs.

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Mixtures

• 2. Calculating What is the percent by mass of
  each type of nut in each can Answer

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Mixtures

• 2. Calculating What is the percent by mass of
  each type of nut in each can AnswerBrand A
  44.2 peanuts 13.64 almonds 16.79 Brazil
  nuts 13.4 cashews 5.77 hazelnuts and 6.21
  pecans
• Brand B 54.8 peanuts 8.90 almonds 5.59
  Brazil nuts 21.06 cashews 4.82 hazelnuts and
  4.82 pecans

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Mixtures

• 3. Drawing Conclusions Do the contents of each
  can meet the FDA regulations Explain. Answer

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Mixtures

• 3. Drawing Conclusions Do the contents of each
  can meet the FDA regulations Explain.
  AnswerYes. Both brands contain more than four
  types of nuts other than peanuts. The masses are
  within the 2 to 80 range.

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Mixtures

• 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
• Answer

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Mixtures

• 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
• Answer The ingredients are listed in order by
  total mass. The ingredient with the largest mass
  is listed first.

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Solutions Suspensions and Colloids

• 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 largest particles a
mixture can be classified as a solution a
suspension or a colloid.
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Solutions Suspensions and Colloids

• Solutions
• When substances dissolve and form a homogeneous
  mixture the mixture that forms is called a
  solution.
• Suspensions
• A suspension is a heterogeneous mixture that
  separates into layers over time.

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Solutions Suspensions and Colloids

• Colloids
• A colloid contains some particles that are
  intermediate in size between the small particles
  in a solution and the larger particles in a
  suspension.
• Like solutions colloids do not separate into
  layers.
• You cannot use a filter to separate the parts of
  a colloid.

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Solutions Suspensions and Colloids

• These liquids represent three categories of
  mixtures.
• Windshield wiper fluid is a solution.
• Muddy water collected from a swamp is a
  suspension.
• Milk is a colloid.

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Assessment Questions

• Which of these substances is a compound
• copper
• water
• oxygen
• carbon

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Assessment Questions

• Which of these substances is a compound
• copper
• water
• oxygen
• carbonANS B

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Assessment Questions

• Which of these groups of letters could be used as
  a symbol for an element
• HF
• Cm
• Car
• fe

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Assessment Questions

• Which of these groups of letters could be used as
  a symbol for an element
• HF
• Cm
• Car
• feANS B

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Assessment Questions

• Which of the following statements does not apply
  to a compound
• It is made of two or more elements.
• It has components that are joined in fixed
  proportions.
• It can be separated into components by physical
  methods.
• It can be broken down into elements or other
  compounds.

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Assessment Questions

• Which of the following statements does not apply
  to a compound
• It is made of two or more elements.
• It has components that are joined in fixed
  proportions.
• It can be separated into components by physical
  methods.
• It can be broken down into elements or other
  compounds.ANS C

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Assessment Questions

• How does a compound differ from a mixture
• A compound cannot be broken down into simpler
  substances.
• Compounds can be separated by physical processes
  and mixtures cannot.
• The composition of a mixture cannot vary.
• A compound is made of two or more elements in
  fixed proportion.

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Assessment Questions

• How does a compound differ from a mixture
• A compound cannot be broken down into simpler
  substances.
• Compounds can be separated by physical processes
  and mixtures cannot.
• The composition of a mixture cannot vary.
• A compound is made of two or more elements in
  fixed proportion.ANS D

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Assessment Questions

• Which of these materials is a heterogeneous
  mixture
• air
• seawater
• sand
• steel

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Assessment Questions

• Which of these materials is a heterogeneous
  mixture
• air
• seawater
• sand
• steelANS C

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Assessment Questions

• Which of the following can be separated with a
  filter
• colloids
• compounds
• solutions
• suspensions

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Assessment Questions

• Which of the following can be separated with a
  filter
• colloids
• compounds
• solutions
• suspensionsANS D