Physical Changes
Physical Properties Physical Properties: characteristics that can be observed or recorded without changing the object. Examples: Color Texture Odor Melting point Boiling point Density You should refer back to what they worked on the day before when they were describing the objects you gave them. These were physical properties. They could see these things just by looking/observing the objects that were in front of them.
Physical properties are used to identify different objects. Most objects have their own unique set of physical properties. Try to guess the object from the physical properties Hard --Salty Brown --Light weight Smooth with bumps --Smells bread like A pretzel! After the kids have had a chance to write the underlined information, reveal the clues at the bottom and let a couple kids guess what they think the object might be.
States of Matter The state of matter is a one physical property! You can observe the state of matter without changing the object you are looking at! Do you know the only object on Earth that exists as all three states naturally? Water is the only object on the Earth that exists naturally in all three states!
Changes in States of Matter While the kids are copying down a rough sketch of this in their notes, explain what they are looking at. Remind them that the pictures with the blue dots are like the pictures that they drew on Monday of solids, liquids, and gases. Then show them that the arrows get more red as they warm up and that heat is really just energy. So as you add energy it will go to a different state. Also that energy helps the molecules inside loose their arrangement. The more energy the less organized they are and the more space can be in between the objects. The same is true if you take that energy away from the object. It will go the other way. Make a quick sketch of this in your notebook
Changes in States of Matter While the kids are copying down a rough sketch of this in their notes, explain what they are looking at. Remind them that the pictures with the blue dots are like the pictures that they drew on Monday of solids, liquids, and gases. Then show them that the arrows get more red as they warm up and that heat is really just energy. So as you add energy it will go to a different state. Also that energy helps the molecules inside loose their arrangement. The more energy the less organized they are and the more space can be in between the objects. The same is true if you take that energy away from the object. It will go the other way. Make a quick sketch of this in your notebook
Changes in States of Matter Energy Released (heat) While the kids are copying down a rough sketch of this in their notes, explain what they are looking at. Remind them that the pictures with the blue dots are like the pictures that they drew on Monday of solids, liquids, and gases. Then show them that the arrows get more red as they warm up and that heat is really just energy. So as you add energy it will go to a different state. Also that energy helps the molecules inside loose their arrangement. The more energy the less organized they are and the more space can be in between the objects. The same is true if you take that energy away from the object. It will go the other way. Make a quick sketch of this in your notebook
Changes in States of Matter Energy Released (heat) While the kids are copying down a rough sketch of this in their notes, explain what they are looking at. Remind them that the pictures with the blue dots are like the pictures that they drew on Monday of solids, liquids, and gases. Then show them that the arrows get more red as they warm up and that heat is really just energy. So as you add energy it will go to a different state. Also that energy helps the molecules inside loose their arrangement. The more energy the less organized they are and the more space can be in between the objects. The same is true if you take that energy away from the object. It will go the other way. Solid Make a quick sketch of this in your notebook
Changes in States of Matter Energy Released (heat) While the kids are copying down a rough sketch of this in their notes, explain what they are looking at. Remind them that the pictures with the blue dots are like the pictures that they drew on Monday of solids, liquids, and gases. Then show them that the arrows get more red as they warm up and that heat is really just energy. So as you add energy it will go to a different state. Also that energy helps the molecules inside loose their arrangement. The more energy the less organized they are and the more space can be in between the objects. The same is true if you take that energy away from the object. It will go the other way. Solid Liquid Make a quick sketch of this in your notebook
Changes in States of Matter Energy Released (heat) While the kids are copying down a rough sketch of this in their notes, explain what they are looking at. Remind them that the pictures with the blue dots are like the pictures that they drew on Monday of solids, liquids, and gases. Then show them that the arrows get more red as they warm up and that heat is really just energy. So as you add energy it will go to a different state. Also that energy helps the molecules inside loose their arrangement. The more energy the less organized they are and the more space can be in between the objects. The same is true if you take that energy away from the object. It will go the other way. Solid Liquid Gas Make a quick sketch of this in your notebook
Changes in States of Matter Energy Released (heat) While the kids are copying down a rough sketch of this in their notes, explain what they are looking at. Remind them that the pictures with the blue dots are like the pictures that they drew on Monday of solids, liquids, and gases. Then show them that the arrows get more red as they warm up and that heat is really just energy. So as you add energy it will go to a different state. Also that energy helps the molecules inside loose their arrangement. The more energy the less organized they are and the more space can be in between the objects. The same is true if you take that energy away from the object. It will go the other way. Solid Liquid Gas Energy Absorbed (heat) Make a quick sketch of this in your notebook
Physical Changes A change in a substance without creating a new substance Please point out that this is now talking about the Physical CHANGES instead of physical properties. One way that I usually stress to the kids what a physical change is: It might look different (physical appearance) but it is the same thing. If you get a hair cut, you might look different, but you are still the same person that you always were. You can paint a wall, but it is still the same wall. You only did a physical change to the wall, the wall is still a wall, but it looks different.
Physical Changes You can change the state of matter by adding energy to, or taking energy away from a substance. Boiling –from liquid to gas Melting –from solid to liquid Freezing – from liquid to solid Condensation –from gas to liquid These are common physical changes that you can do to water, and many other substances on earth to make them look different, but never actually change what you have. This might be a place you could explain how you get complex looking metal solids. You melt them down, gold is still gold even if it is a liquid, then cool or freeze it, and it will be come a solid again, and will also take the shape of the mold it was put into.
Other Physical Changes Can you think of other Physical Changes? Tearing a piece of paper Sanding Breaking a glass Cutting a board You can demonstrate tearing a piece of paper to get the kids thinking if you need to. Discuss how they all might look different than the original, and may not work the way they were intended, but they are still made of the same materials that they were originally made of. Things that are not physical changes, burning an object, putting it in acid, cooking an object,
Physical Changes Cont. Some physical changes can be “undone” You can always re-freeze an ice cube You can always re-condense gas into water All physical changes result in a change in how the substance looks, but not what the substance is! Undone, these are usually just the phase changes talked about earlier in the period. The ones that can’t be undone are when you destroy the object, but not the material.