1. Changes in Matter
ISCI 2002
Chapter 11

2. Phases of Matter Solid (s) ------ Liquid (l) --------- Gas (g)
Phases: ‘physical state’
Solids
Definite volume and shape
Liquids
Definite volume, but form determined by container it is in
Gases
No definite volume or shape

3. Submicroscopic Level Solids Liquids Gases
Strong attraction between molecules- fixed position (vibrate)
Heat breaks fixed arrangement
Liquids
Molecules ‘flow’
Gases
Heat causes attractions between individual molecules to be broken
Move in random manner
Bump into the container – ‘pressure’

4. Diffusion Gas molecules continue to move and bump into each other
Move from higher concentration areas to lower areas of concentration
Occurs in:
Gases, liquids
Diffusion Animation

5. Phase Changes
Animation

6. Process of Evaporation
Molecules are heated below the surface, gain kinetic energy and bump into molecules at the surface
Surface molecules are released (attraction to other molecules broken)
Why is this a cooling process?
The slower moving molecules left behind (lower temperature) cools the air or body (perspiration)

7. Condensation This is a warming process Why?
Gas particles cool and reach the surface. Kinetic energy absorbed by surface molecules. Molecules form attractions
This increases temperature

8. Chemical and Physical Properties
Appearance – hard or soft; dull or shiny; color
Density; melting point and boiling point
Chemical Properties- describes changes of composition the substance undergo’s during a chemical change
What is required to bring about the change
Temperature, heat, number of electrons, etc.

9. Chemical and Physical Properties
Extensive Property
Depends on the ‘quantity’ of matter in a sample
Cannot be used to characterize a type of matter
Mass of water is 2.0 kg? Another sample may be 4.0 kg
Volume, mass
Intensive Property (distinguishes one substance from another)
Property shared by all examples of a specific type of matter
Density (m/v); color; melting point; solubility; acidic or alkaline
The density of water is 1.0 g/cm3

10. Physical and Chemical Properties
Physical change: a change in the physical properties of a substance.
Chemical change: the transformation of one or more substances into others.
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