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Elements Compounds and Mixtures (PowerPoint)

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					  Elements
Compounds
and Mixtures
         I: Elements
   Element: pure substance that can’t be
    separated into simpler substances by
    physical or chemical means.

   Pure substance: contains only one type
    of particle
     Characteristic Properties
   Elements can be id’d by characteristic properties

   Properties that do not change regardless of the
    sample size

   Examples:
       boiling point
       melting point
       density (physical properties)
       reactivity with an acid (chemical property).
    Elements Are Classified by Their
              Properties
   Categories according to shared properties

   Examples:
   iron, nickel and cobalt
       All are:
       shiny, conduct thermal energy and conduct
        electric current
       All are grouped in a single group called metals
        If You Know the Category,
         You Know the Properties!
   If the category is metals, what are the
    properties?

   Hint: we just talked about them
          If You Know the Category,
           You Know the Properties!
   Elements are classified into three categories:
    metals, nonmetals, and metalloids

   Open your text book to page 93

   What are the characteristics of metals,
    nonmetals, and metalloids?

       List and give examples of each one
Metals   Metals account
          for about two
         thirds of all the
          elements and
          about 24% of
         the mass of the
          planet. Metals
           have useful
            properties
            including
             strength,
          ductility, high
         melting points,
           thermal and
             electrical
          conductivity,
         and toughness.
                   Non-metals
   Sulfur
                                    Oxygen atom




Non-metals tend to be brittle and
   non-conductive of heat or
          electricity
Metalloids
        (Si) Silicon is a
           metalloid

        Metalloids are also
         semiconductors
           Summarize:
     which have the following
           properties?

   Which are good conductors of
    electric current?
   Brittle and nonmalleable?
   Shiny?
   Poor conductors of thermal energy?
   Which are good conductors of electric
    current?
             Metals and some metalloids
   Brittle and nonmalleable?
             nonmetals
   Shiny?
             metals and some metalloids
   Poor conductors of thermal energy?
             nonmetals and some metalloids
Elements, Compounds and
        Mixtures

Compounds
    II: Compounds
   Few elements found in nature are found
    alone; most elements are found combined
    with other elements as compounds

   compound: is a pure substance
    composed of two or more elements that
    are chemically combined
       H20- pure substance and compound because it
        is the same type of molecule throughout the
        entire sample
   In an compound, a particle is formed when
    atoms from two or more elements join

   In order for atoms to join, they must react
    or undergo a chemical change with one
    another

   The compound is a new pure substance
    that is different from the elements that
    reacted to form it
common compounds:
        Every Compound Has a
        Unique Set of Properties
   Each compound has its own unique set of
    properties such as boiling point,
    melting point, density and color.

   Compounds can also be identified by
    chemical properties
Compounds Can Be Broken Down
   Into Simpler Substances
   Some compounds can be broken down into
    elements through chemical changes

   Compounds cannot be broken down by physical
    change

   NaCl can be broken back down into their original
    pure substances by adding an electric current to
    the compound.
Compounds Can Be Broken Down
   Into Simpler Substances
   Carbonic acid (or the “stuff” that gives
    soda its fizz, can be broken down into
    Carbon Dioxide and Water

   These can be further broken down into
    carbon, oxygen, and hydrogen through
    additional chemical change
               Show Off
Take out a sheet of paper and answer this question
             in a paragraph to turn in:

   How are compounds and elements alike?
    Different?
   What is a compound?
   A jar contains samples of the elements
    carbon and oxygen. Does the jar contain a
    compound? Support your response
            Let’s Check
           Understanding
   How are compounds and elements alike?
    Different?

     Both are pure substances , but elements cannot be broken
     down into simpler substances; compounds can be broken
     down into simpler substances
     Let’s Check Understanding
   What is a compound?
     A compound is a pure substance composed of two or more
     elements that are chemically combined
      Let’s Check Understanding
   A jar contains samples of the elements
    carbon and oxygen. Does the jar contain a
    compound? Support your response.

    A jar containing samples of carbon and oxygen does not contain a
    compound because the two elements are not chemically combined.
Elements, Compounds and
        Mixtures



Mixtures
         III: MIXTURES
       Pizza Is A Mixture!
   Write out your favorite pizza recipe.
   Don’t forget the ingredients for the crust!
     Pizza Is A Mixture!
   What happens if you don’t like one of the
    ingredients that is on a pizza, or in a
    salad, or in a party mix?




       Mixtures can be physically separated!
               Mixtures
   A mixture is a combination of two or more
    substances that are not chemically
    combined
   Substances in mixtures retain their identity
    which makes the change a ____?_______
    change.
Common techniques for
 Separating Mixtures
Common techniques for
 Separating Mixtures
Common techniques for
 Separating Mixtures
               Try This!
   With your table partner, think of a way
    you might separate a mixture of sand,
    sawdust, and gravel.

   Be prepared to present your suggestions
    to the class!
Unlike Compounds…
          Mixtures do not
          have a definite
          mass ratio. Air is
          an excellent
          example! Some
          days there is more
          water vapor than
          others. These are
          our more humid
          days!
    3 Types of Mixtures
   Solutions

   Suspensions

   Colloids
             Anticipation Guide

Which of these are solutions?

Air          Soft Drinks                  antifreeze

      Ocean water                  brass

       All are solutions! Let’s find out why!
    Let’s Talk Solutions
   A solution is a mixture that appears to be
    a single substance
   Contains particles from 2 or more
    substances
   Described as homogeneous solutions
    because they have the same appearance
    and properties throughout the mixture
     How are solutions
         made?
   They dissolve!
     Dissolving is when the particles in a
     solution separate and spread evenly
     throughout the mixture
What Are the Components
     Of A Solution?
   The solute is the substance or matter
    being dissolved or is soluble (able to be
    dissolved) in the solvent.

   The solvent is the substance into which
    the solute is dissolved
         Think About It!
   In salt water solution, which is the solute
    and which is the solvent?

     The salt is the solute and the water is the
                       solvent.
    Can Solids Be A
      Solution?
                        YES!
Some examples are alloys which are metals or
nonmetals dissolved in metals.
Brass is an alloy of the metal zinc dissolved in copper
Steel, including the steel used to build the Titanic, is an
alloy of the nonmetal carbon and other elements
dissolved in iron.
Examples of Different States in
         Solutions
  What About Matter That
Doesn’t Dissolve In A Solvent?
   This matter is insoluble ( in = not) and
    forms a mixture that is not homogeneous
    and is not a solution.
Some Particles In Solutions Are So
             Small…

How small are they?
   So small that they don’t scatter light!
          Concentrate on
          Concentration
   Concentration: measure of the amount
    of solute dissolved in a solvent
   Concentration is expressed in grams of
    solute per milliliter of solvent
   Concentrations may be described as either
    concentrated or dilute
           Suspensions
   Suspension: is a mixture in which
    particles of a material are dispersed
    throughout a liquid or gas but are large
    enough that they settle out

   The particles in a suspension are insoluble

   Particles are often described as
    heterogeneous mixtures because
    components are easily seen
       The Particles In A
    Suspension Are So Big…
   How big are they?

   They are so big that they scatter or block
    light making most suspensions difficult to
    see through.

   They are too heavy to remain mixed
    without being stirred or shaken
       So, What The Heck Is
             Jello?
   Jello is a colloid!

   Colloid: is a mixture in which the particles are
    dispersed throughout but are not heavy enough to
    settle out.
   The particles are small and fairly well-mixed
   Solids, liquids and gases can be used to make
    colloids
   Other examples: milk, mayo, stick deodorant, and
    whipped cream
        How Small Are The
           Particles?
   Still big enough to scatter light

   And so small that they cannot be
    separated by filtration…they are small
    enough to pass through a filter.
                      Show Off
    Take out a sheet of paper and answer this
        question in a paragraph to turn in:

   What are the 3 differences between
    solutions and suspensions?
       Unlike particles in a solutions, particles in a suspension are
    large enough to settle out, block light, and be trapped by a filter.
                Particles in a solution do none of these.