Chapter 2 Properties of Matter

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Chapter 2 Properties of Matter
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2.1 Classifying Matter

• Pure substance (substance) matter that always
  has exactly the same composition
• Ex. Table Salt, Table Sugar
• Every sample has the same properties due to a
  fixed, uniform composition.

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• Element substance that contains only one type
  of atom, cannot be broken into simpler substances
• Atom smallest particle of an element
• Ex. Carbon, Oxygen, Nitrogen, Gold, Silver,
  Calcium, etc.

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• Symbols for Elements
• 1-3 letters
• First letter is capital
• May be first few letters of element name
• C Carbon Ca Calcium He Helium
• May be derived from latin name
• Fe iron (from latin Ferrum) Au gold (aurum)

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• Compound made from two or more simpler
  substances, joined in a fixed proportion
• Compounds AND Elements are PURE SUBSTANCES
• Ex. Water hydrogen and oxygen
• Ex. Salt sodium and chlorine

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• Mixtures composition is not fixed, properties
  may vary
• Ex. Salsa, spaghetti sauce, sand, salad
  dressing, salt water
• Heterogeneous Mixtures parts are noticeably
  different from one another
• Homogenous Mixtures substances are so evenly
  distributed that it appears to contain only one
  substance

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Heterogeneous Homogeneous
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Solutions, Suspensions, Colloids

• Solution formed when substances dissolve and
  for a homogeneous mixture particles are too
  small to settle
• Suspension heterogeneous mixture that separates
  into layers over time larger particles
• Colloids contain intermediate sized particles
  do not separate into layers particles scatter
  light

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2.2 Physical Properties

• Physical Property any characteristic that can
  be observed or measured without changing the
  composition of a substance
• Viscosity a liquids resistance to flowing
• The greater the viscosity, the slower the liquid
  flows and vice versa
• Conductivity a materials ability to allow heat
  to flow
• Malleability ability of a solid to be hammered
  without shattering

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• Hardness tested by seeing which of two
  materials can scratch the other
• Melting and Boiling Points Temperatures at
  which substances melt or boil

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• Density mass/volume can be used to test the
  purity of a substance
• Most dense substances will sink less dense will
  float

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• Other physical properties include the following
• Color
• Shape
• Texture
• Mass
• Volume
• Weight

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Using Physical Properties

• Identify a material
• Separate the substances in a mixture
• Choose a material for a specific purpose

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Separating Mixtures

• Filtration separates mixture based on the size
  of the particles
• Distillation separates substances based on
  their boiling points

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Physical Changes

• Some of the properties change composition
  remains the same
• Some physical changes can be reversed
• Phase changes (change from solid to liquid to
  gas) are physical changes

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Braiding hair is a reversible phys. change
Cutting hair is a phys. Change that is not
reversible
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2.3 Chemical Properties

• Chemical properties can only be observed when
  substances are changing into different substances
• Flammability ability to burn in the presence of
  oxygen

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• Reactivity how readily a substance combines
  chemically with other substances
• Ex. Rust forms when iron reacts with oxygen
• and water

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Recognizing Chemical Changes

• Three types of evidence for chemical change
• Change in color
• Examples
• Jewelry tarnishing
• Bananas turning black

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• Production of a Gas bubbling, fizzing

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• Formation of a Precipitate
• Precipitate solid that forms and separates from
  a liquid mixture

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