Elements Compounds Mixtures (PowerPoint)

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					        Chapter 4
  Elements, Compounds, &
         Mixtures




Gold      Salt Fields   Granite
               Elements
• Are pure substances that cannot be
  separated into simpler substances by
  physical or chemical changes.

• Elements are found on the periodic table
  of elements
           Pure Substance
• Contains only one type of particle.

• Example: 5 grams of the element gold is
  like all other particles of gold.

• The particles of a pure substance are alike
  no matter where that substance is found.
         Identifying Elements
• Physical properties and Chemical properties are
  ways in which you may identify an element.

• Examples of Physical Properties: melting point,
  density, color, hardness, and texture.

• Examples of Chemical Properties: flammability,
  reactivity with oxygen, acid & water.
  Elements are Classified by their
            Properties
• Elements are divided into three categories:
  Metals, Nonmetals, & Metalloids.
• Elements are classified into groups
  according to their shared properties.
• Example: Iron, Nickel & Cobalt are all
  shiny and conduct electric current
  therefore scientists have grouped them
  into the metal section of the periodic table.
         Metals
Are:
 – Shiny
                                         Copper
 – Good conductors of thermal energy
 – Good conductors of electric current
 – Malleable (hammered into sheets)
 – Ductile (drawn into thin wires)


 Examples: Copper, Lead, Tin
         Nonmetals
• Are:
  – Dull                                  Sulfur
  – Poor conductors of thermal energy
  – Poor conductors of electric current
  – Brittle
  – Unmalleable

  Examples: Sulfur, Bromine, Neon
         Metalloids

                                           Silicon
• Are:
  – Have both properties of metals & nonmetals
  – Some are shiny some are dull
  – Somewhat Malleable and ductile
  – Some conduct thermal energy and electric
    current well

  Examples: Silicon, Antimony, Boron
               Compounds
• A pure substance composed of two or more
  elements that are chemically combined.
• In order for elements to combine they must react
  or undergo a chemical change with another.
• Examples:
   Table salt- sodium and chlorine
   Water- hydrogen and oxygen
• Once the chemical change occurs you have
  another pure substance
• http://www.youtube.com/watch?v=0evGD
  GkOMvc
              Compounds…
• Each compound like elements has its own
  unique set of physical and chemical properties
  that helps you identify it.
                    • Example:
                     -boiling point
                    -melting point
                        -density
                       -color
                       -reactivity
       Compounds in Nature
• Proteins are compounds found in all living
  things.

• Nitrogen is needed to make proteins.

• Plants get their nitrogen compounds from
  the soil. Animals get the nitrogen they
  need by eating plants or animals that have
  eaten plants.
                                Quiz
1. An element is a pure substance that cannot be _________ into other
     substances.
A. combined                     C. made
B. separated                    D. burned

2. Which two categories of elements are good conductors of electricity?
A. Metals and Nonmentals                c. Metals and some Metalloids
B. Nonmetals and Metalloids             d. Water and Metals

3. Elements are divided into three categories
A. metals, nonmetals, metalloids
B. metals, solids, liquids
C. solids, liquids, gasses
D. cobalt, iron, nickel
           Quiz Continued
4. Two or more elements that are chemically
    combined are called___________.
A. metals               C. pure substance
B. elements             D. compounds

5. True or False
    In order for elements to combine they
    must react or undergo a chemical
    change with another.
                  Mixtures
• Are a combination of two or more
  substances that are not chemically
  combined.
• Two or more materials together form a
  mixture if they do not react to form a
  compound.
Example: A Pizza: dough, sauce, pepperoni,
  cheese, olives. They do not react when
  put together.
       Mixtures continued…
• Since no chemical change has occurred
  the substance still has the same chemical
  makeup it had before it was combined with
  the other substances.
• Mixtures can be physically separated. If
  you don’t like olives on your pizza you may
  pick them off. This is a physical change of
  the pizza.
          Mixtures Continued…
• Mixtures are not all as easy to separate. Salt water can
  be separated but you must separate the salt from the
  water by heating the mixture. The water changes from a
  liquid to a gas, and the salt remains.

• Other ways to separate mixtures:
  - Distillation is a process that separates a mixture based
  on its boiling point. (saltwater)
  -Centrifuge separates according to the densities of the
  components. (blood)
  -Magnet can separate iron from aluminum.
    Mixtures vs. Compounds
        Mixtures              Compounds
   1. Are elements,       1. Are elements.
 compounds, or both.    2. Lose their original
   2. Separated by             properties.
    physical means.        3. Separated by
3. They keep original      chemical means.
       properties.
               Solutions
• A mixture that appears to be a single
  substance but is composed of particles of
  two or more substances that are
  distributed evenly amongst each other.

• Example: Saltwater
         Solute vs. Solvent
• In solutions the Solute is the substance
  that is dissolved.
• The Solvent is the substance in which the
  solute is dissolved.

• Example: In saltwater salt is the solute
  or the substance that is dissolved.
  While water is the solvent which
  dissolves the salt.
                     Solubility
• Is the amount of solute needed to make a
  saturated solution.

• If a solution contains all the solute it can hold at
  a given temperature it is saturated. An
  unsaturated solution contains less solute than it
  can hold at a given temperature.

• Mixing, Heating & Crushing all affect how quickly
  solids will dissolve in liquids.
         http://www.youtube.com/watch?v=3G472AA3SEs
                         Suspensions


• Are mixtures that have particles of a material
  throughout it. They settle to the bottom but do
  not dissolve.

• Example: When you shake a snow globe, the
  snow moves around but eventually falls to the
  bottom.
       Colloids

• Are mixtures in which
  particles are dispersed
  throughout but are not heavy enough to
  settle to the bottom. The particles are small
  and fairly well mixed.

• Example: Jello is an example of a colloid.
                         Quiz
1.   A mixture is a combination of ______ substance(s)
     that are not ______ combined.
A.   one, chemically       C. two, chemically
B.   two, physically       D. one, physically

2. True or False
Mixtures can be physically separated.

3. The __________ is the substance that is dissolved, and
     the _________is the substance that dissolves.
A. water, salt                  C. solvent, solute
B. solute, solvent              D. solution, water
                         Quiz
4. Solubility is how much __________ can be dissolved.
A. metal                   C. gas
B. water                   D. solute

5. A snow globe is an example of a ______.
A. colloid                C. solvent
B. suspension             D. compound

6. A ________is a fairly well mixed mixture which the
     particles are not heavy enough to settle out.
A. suspension               C. solution
B. colloid                  D. ratio

				
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