1/12/2010

Post date: Jan 11, 2010 8:9:4 PM

Bell Activity: Give a complete description of the machine on the front table.

Physical properties

• • Characteristics that can be observed without changing the identity of the substance

  • Help identify a substance

  • Can be observed or measured

    • Color

    • Melting point - temperature at which a substance will melt or freeze

    • Boiling point - temperature at which a substance will evaporate or condense

    • Strength - resistance to breaking

    • Hardness - resistance to bending or flexing

    • Magnetism - ability to be attracted to a magnet

    • Conductivity - ability to conduct electricity

    • Density - ratio of mass to volume of a substance

  • Help determine uses for a substance

Density

• • Is mass / volume

  • Is a physical property

  • Is constant for a given substance

  • Can be used to identify a material

  • Is DIFFERENT FROM WEIGHT!!!!!

    • People use "light" and "heavy" for weight and for density

    • Many would say a brick sinks in water because it is "heavy" -- actually, it is because the brick is more dense than water. A boat, which is much "heavier" than a brick, will float in water because it is less dense than water.

  • Density Lab due Thursday (lab can be found in "handouts" section)