- Define and explain What Is a Solid in your own words
- Use key terms such as solid accurately
- Apply what you have learned to new examples and questions
- Avoid the common mistakes learners make with this topic
Ice cubes melt in a warm drink, and candle wax hardens as it cools. Materials can change when they are heated or cooled, and scientists call these conditions states of matter. In this chapter you will explore solids and liquids, and find out what heating and cooling really do.
This lesson focuses on What Is a Solid: discover how solids keep their shape even when you move them.
Discover how solids keep their shape even when you move them.
Key ideas
Solids keep their shape
A solid holds its shape wherever you put it: a wooden block is still a block in your hand, in a box or on the table. You can often change a solid's shape by squashing, bending or cutting it, but it will not flow into a new shape on its own. That is why buildings, furniture and toys are mostly made from solids.
Liquids take the shape of their container
Pour water into a tall glass and it becomes tall and thin; pour the same water into a wide bowl and it becomes short and wide. The water flows because its shape is not fixed, but the amount of water stays the same. This is why we measure liquids by pouring them into measuring jugs.
Key term — solid: A material that keeps its own shape, like a brick or an apple. It does not flow.
Sand pours like a liquid. Explain why scientists still call each grain a solid.
Each grain keeps its own shape and does not flow; only the pile of grains moves.
Answer: Each grain keeps its own shape and does not flow; only the pile of grains moves.
- Calling thick liquids solids Honey, treacle and paint pour slowly, but they still flow and take the shape of their container. Thickness does not make something a solid — flowing does make it a liquid.
- Saying heating always destroys materials Gentle heating often just changes the state of a material, like melting butter. The butter is still butter, and cooling turns it solid again.
Practice
It keeps its own shape wherever you put it and does not flow.
Any sensible pair, for example toast (solid) and milk (liquid).
Cool it down and it freezes back into solid butter, showing no new material was made.
The shape changes to fit the bottle, but the amount (volume) of water stays the same.
Quick check
Which of these best defines "solid"?
Chocolate left in a warm car goes soft. What is this change called, and is it reversible?
- What Is a Solid: discover how solids keep their shape even when you move them.
- Solids keep their shape: A solid holds its shape wherever you put it: a wooden block is still a block in your hand, in a box or on the table.
- melt: To change from a solid to a liquid when warmed, like ice turning to water.
- Watch out for: calling thick liquids solids