Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Matter is anything that has mass and takes up space, consisting of tiny particles such as atoms or molecules like .
Solids have a fixed shape and a fixed volume because their particles are packed closely together in a regular, vibrating pattern.
Liquids have a fixed volume but no fixed shape; they take the shape of their container because the particles are close together but can move past each other.
Gases have no fixed shape or volume and will expand to fill any container because the particles are far apart and move rapidly in all directions.
Heating a substance adds energy to the particles; for example, ice melts into liquid water at .
Cooling a substance removes energy; for example, water vapor turns into liquid water through condensation.
📐Formulae
💡Examples
Problem 1:
If you have of liquid water () in a beaker and pour it into a wide bowl, what happens to its volume and shape?
Solution:
The volume remains , but the shape changes to match the bowl.
Explanation:
Liquids have a fixed volume but take the shape of their container because the particles can slide over one another while staying close together.
Problem 2:
Explain what happens to the particles of a gas when they are cooled down to form a liquid.
Solution:
The particles lose energy, move more slowly, and come closer together.
Explanation:
This process is called condensation. As energy is removed, the attractive forces pull the gas particles together into a liquid state.
Problem 3:
A student notices that a block of ice () keeps its shape on a plate, but a puddle of water () spreads out. Why?
Solution:
Ice is a solid with particles in a fixed lattice, while liquid water particles can flow.
Explanation:
In solids, the strong forces of attraction hold particles in a fixed position, preventing the object from changing shape unless broken.