Matter's Particles
Describe what all matter is made of?
Matter is made of tiny particles that are too small to see.
What are the three states of matter?
Solid, Liquid, Gas
A student mixes salt into water and can no longer see the salt. What happened?
The salt particles spread throughout the water but are still present.
A piece of cardboard is cut in half. Is this a physical or chemical change?
Physical, the substance is still cardboard
What does it mean when we say a new substance has formed?
The material has undergone a chemical change
How are the particles in a solid different from the particles in a gas?
Solid particles are close together and more organized; gas particles are farther apart and move more freely.
What happens when a solid is heated enough to become a liquid?
Its particles gain energy and can move past one another more easily.
Why can't you see the individual particles of salt after it dissolves in water?
The particles are too small to see.
A puddle of water dries up. Is this a physical or chemical change?
Physical, the water is still there just in the air.
Name one piece of evidence that could suggest a chemical change has occurred.
Examples include a new color, new coating/substance, or other evidence
A student puts a water balloon in the freezer. Later, the balloon is frozen solid. What happened to the particles inside the balloon?
They lost energy and moved more slowly/closer together as it became a solid.
What happens to particles when a liquid freezes?
They lose energy and move more slowly.
A student says, "The drink mix disappeared when I stirred it into the water." What would you tell the student?
It didn't disappear; its particles spread throughout the water.
A metal object develops rust. Is this a physical or chemical change?
Chemical, the new substance is rust.
A metal is exposed to the air and develops a green color. What process is occurring?
It has oxidized.
Water is heated and begins becoming steam, what is happening to the particles?
The particles began moving faster, gained energy, and spread farther apart.
A student says, "When water evaporates, the water particles disappear." Explain why this is incorrect.
The particles do not disappear. They spread out into the air.
If the particles of a substance are still present after the substance dissolves, what does this show about matter?
Matter is made of particles that can be too small to see.
What is the most important question you should ask when deciding whether a change is physical or chemical?
Did a new substance form?
Why is rusting considered a chemical change instead of just a change in appearance?
The metal reacts and forms a new substance/coating
Why are particle models useful even though we cannot actually see the particles?
It explains how the particles are arranged and how they move.
A wet sidewalk dries after several hours. Where does the water go?
The water particles gain energy and spread farther apart into the air.
A student dissolves sugar in water. Explain how this situation proves that matter is made of tiny particles.
The substance is no longer visible, but its particles are still present and spread throughout the water. The water is still sweet from the sugar, proving that it there.
A student bends a metal wire into a different shape. Another student burns a piece of paper. Explain how the two changes are different.
Bending the wire changes its shape but does not create a new substance. Burning the paper creates new substances, so it is a chemical change.
A copper object changes color after being outside for a long time. Explain how oxygen can be involved in this change.
The copper reacts with oxygen in the air, oxidizes, and turns green.