THERMAL EXPANSION OF
SOLIDS, LIQUIDS & GASESTOPIC 11: THERMAL PROPERTIES OF MATTER
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HOW DOES THE SIZE OF MATTER CHANGE DUE TO
THERMAL ENERGY?
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FOCUS ONTHE SUBSTANCE’S
SIZE
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OF THE MATTER
THERMAL ENERGY
CAN
Change the lengths of
solids
Change the volumes of liquids & gases
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WHAT DO WE KNOW?When heat is applied to a substance.
The substance’s size increases in all direction.
Heat Energy Applied
Expansion
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Heat Energy Applied
WHAT DO WE KNOW?When heat is removed from a substance.
The substance’s size decreases in all direction.
Heat Energy Removed
Contraction
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Heat Energy Removed
WHY DOES MATTER EXPAND
AND CONTRACT?
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ON HEATINGIts particles gain energy and vibrate more vigorously.
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The structure expands.
The increased movement causes an increase in the intermolecular distance.
ON COOLINGIts particles lose energy and vibrate less.
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The structure contracts.
The decreased movement causes a decrease in the intermolecular distance.
THERMAL EXPANSION
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SOLIDLIQUIDGAS
EXPANDS MORE THAN
EXPANDS MORE THAN
UNEVEN EXPANSION OF MATTERWhen two types of solids of different expansion rates are joined together the overall structure will expand
unevenly if heated.
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Uneven expansion causes the structure to bend.
Even ExpansionUneven
Expansion
UNEVEN EXPANSION OF MATTERThe direction of bending depends on the expansion rate of the solids and its position on the structure.
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The structure will bend downwards if the top layer
expand faster.
The structure will bend upwards if the bottom
layer expand faster.