Particle Model & States of Matter
Name the three main states of matter.
Solid, liquid, gas
Does heating a substance make its particles move faster or slower?
Faster
Name one process where a liquid turns into a gas.
Evaporation or boiling
Does heating usually make substances expand or contract?
Expand
What type of liquid is commonly used in a liquid thermometer?
Mercury or colored alcohol
Indigenous communities often observe seasonal changes to understand when to travel, harvest, or hunt. How does particle movement change as temperatures drop from fall to winter?
Particles slow down; matter contracts; states of matter can change (e.g., liquid water freezes).
Explain the connection between particle movement and temperature in degrees Celsius.
Temperature measures the average energy of particles. Higher temperatures mean particles move faster; lower temperatures mean they move slower.
Explain evaporation using the particle model.
Evaporation happens when the fastest-moving particles at the surface of a liquid escape into the air as gas.
Give one everyday example of expansion and one of contraction.
Expansion: Metal rails in summer lengthen.
Contraction: Water pipes shrinking in winter.
At what temperature does water freeze? At what temperature does water boil?
Water freezes at 0*C and it boils at 100*C.
Describe what happens to the particles of a solid when it melts into a liquid using the particle model. Give an example.
In a solid, particles are close together and vibrate in place. When it melts, particles gain energy, move faster, and can slide past each other. Example: Ice melting into water.
How does temperature affect the pressure of a gas in a closed container? Use particle movement in your answer.
Higher temperature makes particles move faster, which means they hit the container walls harder and more often, increasing pressure. Lower temperature slows them down, reducing pressure.
Many Indigenous teachings emphasize respect for water because it changes forms. What state changes happen in the water cycle?
Evaporation, condensation, freezing, melting.
Explain why it is important to understand expansion and contraction when building a structure like a bridge or a road.
Materials expand when hot and contract when cold. Engineers need to allow space for this to prevent cracking, bending, or breaking of bridges and roads.
Why does the liquid inside a thermometer move up and down when temperature changes? Use particle movement in your answer.
Heating makes the particles move faster and push apart, causing the liquid to expand and rise. Cooling slows particle movement, liquid contracts, and level drops.
Compare the particle movement in liquids and gases. Explain why gases spread to fill a container.
In liquids, particles are close together but can slide past each other. In gases, particles are far apart and move freely in all directions. Gases spread to fill a container because the particles move randomly and quickly, spreading out.
A cup of water is heated from 20°C to 80°C. Describe what is happening to the particles during this heating.
The particles gain energy and move faster. They start moving more freely, which can eventually lead to evaporation if the water gets hot enough.
Explain what happens to the particles of a solid when it sublimates (turns directly into gas).
In sublimation, particles gain enough energy to break free from the solid structure without becoming liquid first. They move far apart and quickly as gas particles. Example: Dry ice turning into carbon dioxide gas.
A metal rail expands on a hot day. Predict what might happen if engineers didn’t leave space for expansion.
The rail could bend, buckle, or break because the expanding metal has nowhere to go.
Why does a tire look more “flat” on a cold day than it does on a warm day?
When it’s warm, the particles move faster and spread out more, making the tire look more full. When it’s cold, the particles slow down and come closer together, making the tire look more flat even thought there is the same amount of air inside
Predict what would happen to particles if a gas was cooled rapidly. Use the particle model to explain your reasoning.
Cooling slows down the particles’ movement. If cooled enough, the gas could condense into a liquid because the slower particles can come close together and form bonds.
If two substances at different temperatures are mixed, which way does heat flow? Explain using particle motion.
Heat flows from the warmer substance to the cooler one. Particles in the warmer substance transfer energy to the slower-moving particles in the cooler substance until they reach the same temperature.
A puddle of water disappears on a hot day. Explain the process in terms of particle movement and energy.
The water particles at the surface gain energy from the sun, move faster, and escape as gas. This is evaporation. The faster the particles move, the more likely they are to leave the liquid.
Why do engineers use gaps in sidewalks or bridges? Explain using particle movement.
Gaps allow the material to expand when particles move faster due to heat, preventing cracks or damage. When it cools, the material contracts, and the gap accommodates this change.
Explain how temperature changes in your classroom could be shown using a liquid thermometer. Include the role of particle expansion and contraction.
If the classroom warms up, liquid particles move faster, expand, and the level rises. If it cools down, particles slow, contract, and the level falls, showing the temperature change.