Good Science Victorian Curriculum Year 7
Digital sample of Matilda's newest publication, Good Science Victorian Curriculum Year, authored by Emma Craven and Aaron Elias. For more information visit www.matildaeducation.com.au or email Katrina Tucker, katrinatucker@matildaed.com.au
Digital sample of Matilda's newest publication, Good Science Victorian Curriculum Year, authored by Emma Craven and Aaron Elias. For more information visit www.matildaeducation.com.au or email Katrina Tucker, katrinatucker@matildaed.com.au
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CHEMICAL SCIENCES<br />
4.4<br />
CHANGING<br />
STATES<br />
Water is the only substance on Earth that exists as a solid, liquid<br />
and gas. Solid water is ice. If you heat it, the ice melts into liquid<br />
water. If you keep heating, it boils and becomes water vapour.<br />
The particle model and your understanding of how heat<br />
affects particles can be used to explain these changes in state.<br />
LEARNING INTENTION<br />
At the end of this lesson I will be<br />
able to describe some of the key<br />
processes that take place as<br />
matter changes states.<br />
Figure 4.12 Water can change state from solid to liquid to gas as<br />
heat is added. If heat is taken away, the changes are reversed.<br />
Melting<br />
Evaporation<br />
KEY TERMS<br />
boiling point<br />
the temperature at which<br />
something changes from a<br />
liquid to a gas<br />
Solid<br />
Freezing<br />
Liquid<br />
Condensation<br />
Gas<br />
condensation<br />
changing from a gas to a liquid<br />
evaporation<br />
changing from a liquid to a gas<br />
melting point<br />
the temperature at which<br />
something changes from a<br />
solid to a liquid<br />
LITERACY LINK<br />
LISTENING<br />
Choose a section from this<br />
lesson to read aloud to a partner.<br />
Your partner draws a diagram<br />
based on what you have read,<br />
showing particles during a<br />
state change.<br />
1<br />
Solids can melt to liquids when heated<br />
Melting is the change of a solid to a liquid. The melting point is<br />
the temperature when something changes from a solid to a liquid.<br />
This is different for every substance.<br />
The particles of a substance in its solid state are<br />
strongly attracted and don’t move very much –<br />
they just vibrate back and forth. As you add<br />
heat energy, the particles move faster and<br />
vibrate more. If you add enough heat,<br />
the particles have enough energy<br />
to break free of the solid structure<br />
and move around each other.<br />
The substance is now a liquid.<br />
Which state of matter<br />
undergoes melting?<br />
NUMERACY LINK<br />
DATA<br />
Ash heated some water over a<br />
Bunsen burner and recorded<br />
the temperature every minute<br />
for five minutes. His results were<br />
45°, 54°, 90°, 70° and 75°. Does<br />
this data look valid? What should<br />
Ash’s next step be?<br />
Hint: See lesson 1.4 for a<br />
definition of valid data.<br />
Figure 4.13 When particles in a<br />
solid such as wax speed up, the<br />
solid can melt to form a liquid.<br />
60 GOOD SCIENCE VICTORIAN CURRICULUM 7
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