Chapter 12 - Properties of Matter

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Chapter 12 - Properties of Matter

• 12.1 Properties of Solids
• pp. 270-275
• 17.1 Chemical Reactions
• pp. 384-387

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PROPERTIES OF SOLIDS

• Different kinds of matter have different
  characteristics.
• Characteristics that you can observe directly are
  called physical properties.
• Substances can be identified by their physical
  properties.

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Physical Properties

• Can be observed or measured without changing the
  identity of the matter
• Include
• Color odor mass
• Volume density solubility
• Malleability ductility
• State of matter
• Thermal conductivity

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malleability

• The ability to be pounded into thin sheets
• Example Aluminum can be rolled or pounded into
  sheets to make foil

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ductility

• The ability to be drawn into a thin wire
• Example copper can be drawn into a thin wire

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Density

• Formula used to calculate density
• D m
• V
• Where D density (measured in g/cm3)
• m mass (measured in g)
• And V volume (measured in cm3)

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DENSITY OF A SOLID

• Depends on two things
• The mass of the object
• How tightly packed together the atoms are.

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TWO TYPES OF SOLID

• Crystalline solid
• particles are arranged in a repeating pattern of
  rows.
• Ex. diamond, ice, iron, salts, minerals,
  metals
• Amorphous solid
• Particles are not in any particular order
• Examples include oobleck, rubber, wax, glass

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• Tensile strength
• A measure of how much stress from pulling a
  material can withstand before breaking. Brittle
  materials have low tensile strength.
• Hardness
• measure's a solids resistance to scratching.
• Ex. MOHS scale of hardness.

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• Elasticity
• This describes a solid's ability to be stretched
  and return to its original shape.
• Brittleness- the tendency of a solid to crack or
  break before stretching very much.
• Glass is a brittle material.

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Physical Changes

• A change that affects one or more physical
  properties of a substance
• Physical changes can be undone

• Examples freezing water for ice cubes
• Cutting your hair
• Bending a paper clip

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Chemical Properties

• describe a substance based on its ability to
  change into a NEW substance with DIFFERENT
  properties
• Include
• flammability (the ability to burn)
• Reactivity to oxygen
• Reactivity with water
• Reactivity with acids

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Chemical Change

• A chemical change occurs when one or more
  substances are changed into COMPLETELY DIFFERENT
  substances with DIFFERENT PROPERTIES

• Example baking a cake

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Clues to Chemical Changes

• Change in color
• Fizzing
• Foaming
• Heat
• Production of sound, light or odor

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Chemical Changes

• Cannot be undone by ordinary physical means
• Some chemical changes may be undone by other
  chemical means
• Example Water formed in the space shuttles
  rockets could be split back into hydrogen and
  oxygen using electricity