Ch 1

• Properties


  Characteristics of matter scientists can use to categorize different types of matter
• Ways to categorize matter

  • By state
  • By composition
• Gas


  • Particles widely separated, no definite shape or volume
• Liquid


  • Particles closer together, definite volume but no definite shape
• Solid


  • Particles are very close together, define shape and definite volume
• Pure substance


  A substance that has only one component
• Mixture


  A combination of two or more pure substances in which each substance retains its own identity, not undergoing a chemical reaction
• Element


  A pure substance that cannot be changed into a simpler form of matter by any chemical reaction
• Compound


  A pure substance resulting from the combination of two or more elements in a definite, reproducible way, in a fixed ratio
• Types of mixtures

  • Homogeneous
  • Heterogeneous
• Physical property

  Is observed without changing the composition or identity of a substance
• Physical change

  Produces a recognizable difference in the appearance of a substance without causing any change in its composition or identity
• Physical changes

  • Conversion from one physical state to another
  • Melting an ice cube
• Separation by physical properties

  • Magnetic iron is separated from other nonmagnetic substances, such as sand
• Chemical property


  Results in a change in composition and can be observed only through a chemical reaction
• Chemical reaction (chemical change)

  A chemical substance is converted in to one or more different substances by rearranging, removing, replacing, or adding atoms
• Classification of properties

  • Color
  • Flammability
  • Hardness
  • Odor
  • Taste
• Classification of changes


  • Boiling water becomes steam
  • Butter turns rancid
  • Burning of wood
  • Mountain snow melting in spring
  • Decay of leaves in winter
• Intensive properties


  A property of matter that is independent of the quantity of the substance
• Extensive properties


  A property of matter that depends on the quantity of the substance
• Units

  The basic quantity of mass, volume or whatever quantity is being measured
• English system


  A collection of functionally unrelated units, difficult to convert from one unit to another
• Metric System


  Composed of a set of units that are related to each other decimally, systematic
• Mass


  The quantity of matter in an object, not synonymous with weight
• Length


  The distance between two points
• Volume


  The space occupied by an object
• Time


  The metric unit is the second (s)
• Metric system prefixes

  • Basic units
  • Kilo (k)
  • Hecto (h)
  • Deca (da)
  • Deci (d)
  • Centi (c)
  • Milli (m)
  • Micro (μ)
  • Nano (n)
  • Pico (p)
• Volume = Length x Width x Height
• Significant figures

  All digits in a number representing data or results that are known with certainty plus one uncertain digit
• Significant figures examples

  • 7.314 has four significant digits
  • 73.14 also has four significant digits
  • 60.052 has five significant digits
• Use of zeros in significant figures

  • Significant if the number contains a decimal point
  • Insignificant if the number does not contain a decimal point
  • Zeros to the left of the first nonzero integer are not significant
• 3.400 has four significant figures, 3004 has four significant figures, 300. has three significant figures, 0.003040 has four significant figures
• Scientific notation

  Used to express very large or very small numbers easily and with the correct number of significant figures
• Converting a number greater than 1 to scientific notation


  The original decimal point is moved x places to the left, and the resulting number is multiplied by 10^x
• Converting a number less than 1 to scientific notation


  The original decimal point is moved x places to the right, and the resulting number is multiplied by 10^-x
• Scientific notation examples

  • 0.0000000000000000000000066466 g must be entered into calculator as 6.6466 x 10^-20 g
• 0.00018 in scientific notation is 1.8 x 10^-4, 3004 in scientific notation is 3.004 x 10^3, 300. in scientific notation is 3.00 x 10^2, 0.00304 in scientific notation is 3.04 x 10^-3
• Accuracy


  The degree of agreement between the true value and the measured value
• Error


  The difference between the true value and our estimation, can be random or systematic