الأسبوع 8 · المحور الثاني «المادة والطاقة»، الوحدة الثانية «حركة الجسيمات»: ابدأ، نظرة عامة على مشروع الوحدة، المفهوم 2.1 «المادة في العالم من حولنا» (أ) · 3 دروس
2
Three faces of water
Discovery Education Science P5: Term 1, Unit 2, pp. 122–126
GoalDescribe the three states of water and tell solids, liquids and gases apart by shape and volume.
New words
volume · the amount of space something takes upwater vapour · water as an invisible gasshape · the outline of something
Explanation
Water is the only common matter we meet in all three states. Ice is a solid, water is a liquid, and water vapour is a gas. Steam that you can see over a kettle is tiny droplets of liquid water; the water vapour itself cannot be seen. A solid keeps its own shape and has its own volume. A liquid has its own volume but takes the shape of its container: 200 mL of juice is 200 mL in a tall glass and in a wide bowl. A gas has no shape or volume of its own: it spreads out to fill the whole container. When we say “a gas fills its container” we mean it spreads evenly through the whole space inside.
ice (solid)→water (liquid)→water vapour (gas)
Worked examples
State
Own shape?
Own volume?
solid
yes
yes
liquid
no
yes
gas
no
no
Hossam compares the three states in a table. Check each row against the explanation.
tall glass: 200 mLpour→wide bowl: 200 mL
Hana pours 200 mL of juice from a tall glass into a wide bowl. The shape of the juice changes, but its volume stays 200 mL.
The ice melts in a cup. The solid ice changes to liquid water, and if the water is heated it changes to water vapour.
Class activity
Ice watch (a grown-up helps). Put 3 ice cubes in a cup on a plate and leave it in a warm room. Look every 10 minutes for 30 minutes and draw what you see. Write when it was solid, when it was liquid, and which state is missing from the cup (and where it could be).
Practice
1
Name the three states of water and one example of each.
Solid: ice. Liquid: water in a cup. Gas: water vapour.
2
What do you see over a kettle: water vapour or tiny droplets of liquid water?
Tiny droplets of liquid water. Water vapour cannot be seen.
3
You pour 300 mL of milk from a jug into a wide pan. How many mL of milk are in the pan?
jug: 300 mLpour→pan: ? mL
300 mL. The shape changes but the volume stays the same.
4
Which state has no shape and no volume of its own?
