Chemistry is the study of the properties and behavior of matter.

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Chemistry is the study of the properties and
behavior of matter.

• Matter
• Physical material of the universe
• Has mass
• Occupies space

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Properties of Matter

• Physical properties Measured without changing
  the substance (melting point, color)
• Chemical properties Describe how substances
  react to form different substances (hydrogen
  burns in oxygen)
• Intensive properties Do not depend on the
  amount of substance (melting point)
• Extensive properties Depend on the amount of
  substance (mass, volume)

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States of Matter(macroscopic level)

• Gas
• No fixed volume or shape
• compressible
• Liquid
• Volume independent of container, no fixed shape
• Incompressible
• Solid
• Volume and shape independent of container
• Incompressible, rigid

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States of Matter(molecular level)

• Gas
• Molecules far apart,
• Move at high speeds, collide often
• Liquid
• Molecules closer than those in gas,
• Move rapidly but can slide over each other
• Solid
• Molecules packed closely in definite arrangements

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Separation of Mixtures

• Separation techniques exploit differences in
  properties of the components
• Filtration To remove solid from liquid
• Distillation To boil off one or more components
• Chromatography To exploit solubility of
  components

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Elements Compounds

• An element is a substance made of one kind of
  atom.
• Examples are oxygen and silicon.
• A compound is a substance made of two or more
  elements.
• Has different properties than those of the
  elements from which it is made.
• Example is SiO2 (glass or sand).
• Elements are combined in a specific proportion.

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Compounds

• A compound is a substance of 2 or more elements,
  chemically combined.
• Plants make glucose.
• Geologic processes make calcium carbonate.
• Two types of compounds
• Molecular compounds
• Ionic compounds

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Molecules

• A molecule is a particle of matter made up of two
  or more atoms held together by SHARING of
  electrons.

N2 Nitrogen
CO2 Carbon dioxide
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Mixtures

• Mixtures are substances made of two or more
  parts.
• Not combined chemically
• Make-up or composition may vary (soil)
• Parts of mixtures keep their original properties.
• Parts can be separated by physical means.
• Distillation, evaporation and filtering are
  examples of physical means.

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Mixture vs. Compound
Mixture Compound
Composition may vary. Composition is constant.
Components keep their original properties. Properties are different than those of its components.
Components are not chemically combined. Components are chemically combined.
Components can be separated by physical means. Components usually require chemical means for separation.
Composition how something is made. (Compose
To make.) Component a part vary differ
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Properties of Mixtures

• Can be made up of any number of compounds or
  elements.
• Homogeneous mixture All parts are alike.
• Uniform
• Any sample contains same amount of each
  component.
• Milk and orange juice are examples.
• Heterogeneous mixture Not every part has the
  same composition.
• Non-uniform
• One sample may have more of one component than
  another sample.
• Soil and garlic salt are examples.

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Properties of Matter

• Physical properties Measured without changing
  the substance (melting point, color)
• Chemical properties Describe how substances
  react to form different substances (hydrogen
  burns in oxygen)
• Intensive properties Do not depend on the
  amount of substance (melting point)
• Extensive properties Depend on the amount of
  substance (mass, volume)

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Classifying Substances
Substance Element, Mixture or Compound? Homogeneous or heterogeneous mixture? Ionic or molecular compound?
Metal alloy (steel) mixture homogeneous
Tin element
Brass mixture (Cu,Zn) homogeneous
Carbon dioxide (CO2) compound molecular
Calcium Carbonate (CaCO3) compound ionic
Ammonia (NH3) compound molecular
Cement mixture heterogeneous
Ink mixture homogeneous
Cola with ice mixture heterogeneous
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Periodic Table

• The modern periodic table shows the position of
  the element is related to
• 1. Atomic number AND
• 2. Arrangement of electrons in its energy levels

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Periodic Table Organization

• Nonmetals Upper right corner plus hydrogen. 
• Metals 80 of elements to left of zig-zag
  line. 
• Metalloids Have properties of both metals and
  nonmetals. They border the zig-zag line.  
• Rare Earth Metals Two rows of elements
  separated to make it more convenient size.
• Period Horizontal row of table  
• Group Vertical column of table

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Groups Predict Properties

• Alkali metals in Group I are the most reactive
  elements due to 1 valence electron
• Halogens in Group 17 combine with metals to form
  salts
• Noble gases in Group 18 are not reactive due to 8
  valence electrons (2 for He)
• Elements behave chemically like those closest to
  them on the table, particularly in same group.

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Properties of Metals

• 1.Malleable (can be shaped without breaking)
• 2.Ductile (can be pulled into wire)
• 3.Have luster (are shiny)
• 4.Conduct electricity (Electrons are free to
  move.)
• 5.Have a low number of electrons in their outer
  energy levels ( 1 to 3)

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Nonmetals

• No luster
• Not good conductors
• Many valence electrons (4 or more)
• Carbon Component of living things
• Entire branch of chemistry devoted compounds
  containing carbon Organic Chemistry

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Metalloids

• Along zig-zag line (not including Al)
• Have properties of metals and non-metals
• Often shiny like metals
• Conduct heat and electricity
• Common use is semiconductors, computer chips
• Semiconductors conduct electricity when other
  elements are incorporated into them