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TGB2
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‘The
particles of one substance are all the same’
The salt animation has thicker lines, so students should predict
that salt particles will experience a stronger hold.
‘The particles are always moving in some way
– they have an energy of movement
Heating gives the particles more energy of movement
– they are more energetic’
In both animations, students will see particles shaking around
on the spot but not moving from place to place.
The animations show the particles vibrating more vigorously
at 50°C than at 20°C.
What are the particles really like?
This is an important point, as many students wrongly believe
that the particles of a substance share the macroscopic properties
of the substance, so a ‘runny’ sample would have
‘runny’ particles, for example. You can read more
about students’ ideas in 'Key
Features of Students' Understanding' in the Teachers’
Guide.
Particles in the liquid state – notes on animation
Students should notice that the particles in the liquid state
are no longer in an orderly pattern but are moving
around. (For simplicity, the animation does not show the particles
colliding, but the particles would be colliding
with each other all the time). The changes must be associated
with melting and must be because the particles
move more vigorously until they are able to break free from
fixed positions.
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Science Enhancement Programme CD-ROM 2005 |
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