Matter

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Matter
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Chapter Twelve The Physical Properties of Matter

• 12.1 Density
• 12.2 Buoyancy
• 12.3 Properties of Materials

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Investigation 12A
Density

• How does density determine if an object floats or
  sinks?

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12.1 Density

• Density describes how much mass is in a given
  volume of a material.

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12.1 Density

• Solids, liquids and gases are matter, so they all
  have density.

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12.1 Volume

• Volume is the amount of space an object takes up.
• The volume of a rectangular solid is found by
  multiplying length times width times height.

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12.1 Volume

• Measuring the volume of liquids is easy.
• Pour the liquid into a marked container called a
  graduated cylinder and read the volume.

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12.1 Displacement

• You can find the volume of an irregular shape
  using a technique called displacement.
• Find the volume of an irregularly shaped object
  by putting it in water and measuring the amount
  of water displaced.

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12.1 Density

• The units used for density depend on whether the
  substance is solid or liquid.
• For liquids use units of grams per milliliter
  (g/mL)
• For solids use density in units of g/cm3 or kg/m3.

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12.1 Density of common materials

• Density is a property of material independent of
  quantity or shape.

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12.1 Density of common materials

• Liquids tend to be less dense than solids of the
  same material.
• Water is an exception to this rule.
• The density of solid water, or ice, is less than
  the density of liquid water.

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12.1 Determining Density

• To find the density of a material, you need to
  know the mass and volume of a solid sample of the
  material.
• Mass is measured with a balance or scale.
• Use the displacement method or calculate the
  volume.

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12.1 Determining Density

• When calculating volume, all of the units of
  length involved in the calculation must be the
  same.

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12.1 Why density varies

• Density changes for different substances because
• Atoms have different masses.
• Atoms may be packed tightly or loosely.