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Matter

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					          Matter

  The object of the branch of
knowledge known as chemistry
                   Matter
• Particles, as opposed to a continuous
  medium
• Substantial, as opposed to insubstantial
         Matter is substantial
• NOT spirit
  – God, Allah, Buddha, Zoroaster,...
• NOT a quality
  – truth, justice, “the American way”,...
• NOT light
  – light IS particulate, but has no MASS
          Matter is Substantial
• Heat?
  – NO. Heat is insubstantial.
• Fire?
  – Partly.
     • Heat, light, but also MATTER in the process of
       changing
           States of Matter
• Solid
• Liquid
• Gas
                  Solid
• Has a definite volume
• Has a definite shape
                   Solids ?
•   Rock               • Taffy?
•   Hard Plastic
•   Glass
•   Salt
•   Wood
•   Metal
•   Ice
•   Jello
                 Liquid
• Does NOT have a definite shape
• Does have a definite volume
                    Liquids?
•   Water
•   Gasoline
•   Mercury
•   Melted butter
                    Gas
• Doesn’t have a shape or volume
  – Must be contained

             *Balloon

             *Gravity of Earth
                      Gases ...
• Smell
    –   chlorine
    –   ammonia
    –   perfume
    –   vinegar
    –   gasoline? --gas released by liquid ?

•   Don’t smell
    – air gases
     Flexible things ---- Solid?
• Rubber
  – stretches and returns - temporarily changes volume?


• Soft Plastic

• Ductile metal (wire, e.g.)

• Taffy?
      Structure of Matter on a
         Microscopic Scale
• Search for analogies between microscopic
  structure and the familiar
                  Solids
• Pyramids of Egypt - At a distance, appears
  homogeneous, but close enough regular
  array of elements visible.

• Concrete - Close view reveals irregular
  arrangement of elements
                       Liquids
• Plastic balls in children’s amusement?
  – More like jello

• Office filled with balloons ?
  – Still like jello

• Fluidized bed
                 Gases
• How can a gas be modelled?
             Pure Substances
• Like Platonic Forms
  – A “perfect” example of a thing;
     • For example, “water” means something very
       precise. Even though the word may be used for
       many different particular samples, it really means
       the pure material....
             What is water?
•   River water
•   Dirty water
•   Mineral water
•   Sparkling water
•   Sea water
•   .....?
        -------Modifiers are required to
      distinguish these from plain water
     What is a pure substance?
• TEST: Does the substance vary from
  sample to sample?
• Substance is chemically an element or a
  compound - NOT a mixture.
                  Variation
• Oil
  – different companies, grades, viscosities, colors,
    additives...
• Milk
  – “whole” milk varies from cow to cow, animal
    to animal...
• Salt
  – “Sea” salt? Smelling salt(s)?
                 Elements
• The smallest particles of an elemental
  substance are all the same
• Substances can not be transformed into
  other elements*
• Only 110 named, only about 115 known
• Listed and organized in the periodic table
  * --except by non chemical methods
 Compound = “Pure Compound”
• Every sample contains a definite fixed
  proportion of the same elements
• A compound can not be separated into
  different fractions with different properties
                  Mixture
• Properties of a mixture are a combination of
  the properties of the pure substances which
  make it up.
• Mixtures vary, at least slightly, from sample
  to sample.
• Can be separated into fractions with
  different properties
  – distillation
  – chromatography
Homogeneity and Heterogeneity
• Mixtures which appear perfectly uniform
  throughout are said to be homogeneous
  – broken glass, hard plastic, metal, ...
• Mixtures which appear to vary throughout
  are said to be heterogeneous
  – the grain of wood ...
 Properties of Matter distinguish
     them from each other
• Physical properties
• Chemical properties
            Physical properties
• Density
  – mass (?) per unit volume (?)
     • Typical: “grams per cubic centimeter”
     • grams, kilograms, slugs (?)
     • meters, centimeters, inches, feet,...
    Fundamental physical quantities
•   Length
•   Mass
•   Time
•   Temperature
•   Electric current
•   Luminous intensity
•   Amount of substance
Measurement
     Precision of Measurement
• Precision refers to the “fineness” with
  which the measurement is done
  – 1.001 inches
     • a measurement to the nearest one part in one
       thousand
  – 1.00
     • a measurement to the nearest one part in one hundred

   Both measurements could be “correct,” but the first one
                     is more precise
     Accuracy of measurement
• Accuracy refers to the “correctness” of the
  measurement - how close the measurement
  is to the true value
  – A measurement was repeated. The two values
    obtained were 1.01 and 0.99. If the true value
    is 1.00, the two measurements were equally
    accurate
                  SI units
• Fundamental unit for each quantity
• Prefixes for economy of expression
  – e.g., a meter is the length standard. One
    thousand meters is expressed as one kilometer
        Prefixes for SI units
1000                 Kilo- k
1,000,000            Mega- M
1,000,000,000        Giga- G
1,000,000,000,000    Tera- T
One one-thousandth   Milli- m
One one-millionth    Micro- 
One one-billionth    Nano- n

				
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