Classification of Matter

1
Classification of Matter

• Definitions

2
Pure Substances

• A pure substance has its own characteristic
  properties.
• All samples of a substance will have the same
  properties while at the same conditions
• Elements
• Compounds

3
Elements

• 110 known elements
• Each element has its own characteristic
  properties
• Cannot be broken down by ordinary chemical means
• Divided by properties into metals, nonmetals and
  metalloids (properties of both metals and
  nonmetals)

4
Compounds

• Two or more elements chemically combined to form
  a new substance with its own set of physical and
  chemical properties
• 2H2 O2 ? 2H2O
• A compound may be broken down by chemical means
  into its constituent elements
• 2H2O ? 2H2 O2

5
Physical Properties

• Properties which can be observed and measured
  without the production of new substances
• Metals
• Conduct electricity and heat energy
• Some are Malleable (hammered into shapes)
• Some are Ductile (Can be drawn into wires)

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Other physical properties

• Density (mass per unit of volume) or Dm/v
• Hardness
• Solubility or insolubility
• Boiling/melting points

7
Physical Properties III

• - A physical change does not change the identity
  of a substance
• - Physical properties are dependent on
  temperature, pressure, and phase.
• - Molten lead is less dense than solid lead
• - Boiling point depends on atmospheric pressure
• (Water boils at 93C in Denver)
• Ice is less dense than water, because of the
  crystalline structure of water as it freezes
• Ice floats on water

8
Chemical Properties

• How a substance interacts with other substances
  (or fails to react)
• Rusting of iron (iron reacts with water to form
  iron oxide
• Relative inertness of nitrogen (does not react
  with most other substances)
• A chemical change results in the formation of a
  new substance

9
Mixtures

• Mixtures can have their own set of properties,
  and these properties can change as the mixture
  changes.
• The boiling point of a salt/water solution is
  dependent on the concentration of salt.