Unit 1 Physical Properties of Matter

Who Do You Know? Picture a student walking into the classroom. How would you tell if it were your friend? What characteristics would you use? Describe the person in your mind to your group. What are some useful characteristics or properties to describe people?

Developing a Particle Model of Matter through Investigative Reasoning

What is Modeling? Write a brief statement about what you believe a model is and how it is used in science. What examples of models have you used in other science classes?

What is ‘modeling?’ Explanatory models in science are an explanation for something that is observed in the physical world. Such models are constantly being evaluated by a community of scientists. To evaluate a particular model, scientists ask: Can the model explain all the observations? Can the model be used to predict the behavior of the system if it is manipulated in a specific way? Is the model consistent with other ideas we have about how the world works and with other models in science?

Investigation: Can You Name and Describe It? Get These paper plate 6 samples of substances scooper Do This 1. Decide in your group on what properties to look at. What are some physical properties of matter? 2. Create a chart like the one on the next slide, and write in the properties you have decided to study. Be sure to label your table. 3.. Look closely at these properties for each of the substances. Emphasize the differences Try to figure out what each substance is, based on the properties you study.

Table: Properties of Substances SAMPLES Property A Property B Property C Property D Property E Soluble in water Property F Reaction with vinegar sample 1 sample 2 sample 3 We will be investigating 6 samples

Conclusion ?s Observing and using Evidence for Inference 1.Which observations were: – Physical Properties – Chemical Properties Which observations were: – Quantitative – Qualitative

2.Are there other properties that would have been useful in identifying the substances that you did not use. What if you had a well equipped lab, what else might you use to observe and describe? 3.How does the quantity of substance influence observations. Would a large amount be different than a small amount? 4.What if the substances were all clear liquids? Would you be able to use the same properties to describe them? What might you do to decide what the clear liquids are?

Investigation: How Small? Get These: paper plate different samples of sugar magnifying glass or microscope Step A Use the magnifying glass to examine the first sample of sugar—the cube. Study it very carefully. Draw a picture of what it looks like magnified. Then use words to describe what you are seeing and drawing. Step B Your teacher will provide some other samples of sugar, including powdered sugar. Study them under the magnifying glass or microscope. Record what you see. Use a mortar and pestle to grind sample C until it is as small/fine as you can possible get it. Observe carefully Do you see evidence that the powdered sugar is made of the same substance as the sugar cube? Or do they look like different substances?

HOW small Consider the evidence. – Do you see any evidence that the powdered sugar is made of the same substance as the sugar cube? – Or do they look like difference substances. – Using both evidence and logically thinking, what do you think? Is the ground substance still sugar?

After completing these observations, a student suggests that everything might be made of smaller parts: the table and chairs, the books and pencils, the air, even people – she suggests that all of us might be made of tiny particles. Her idea is that if we just had the right tools, we could take a piece of paper and break it down into smaller and smaller particles, so small we could not see them without microscopes. Another student argues that while this may be true for some large objects, the ‘breaking down’ must stop somewhere, so not everything can be made of tinier parts. To what extent do you agree or disagree with either these ideas about matter? Explain your reasoning, use evidence from the last two sets of observations in your writing.

1. Particle model of matter What is matter composed of?? Small bits or particles

Swab the Deck Moisten a cotton ball with alcohol and then drag it across the lab table to make a streak about a foot long. Watch the streak for a minute or two. Describe what you see and smell using words and pictures. Explain what happened (give your best guess). Where do you think the alcohol went? Why did it do this? Use words and pictures. Can you think of an alternate explanation? How might someone else explain these observations.

Group White Board – Consider each group members explanation. – Agree as a group on an explanation and draw a picture that shows what the group thinks might be happening to the alcohol. – Pictures only, no words Redraw your original picture if your thinking changes

Based on the evidence thus far: Is it reasonable to say that all things in the world around us are made of extremely tiny particles? How small are they? Do particles move?

Particle Model of Matter Matter is composed of small bits, or particles. These particles have motion

Drops Away Place a large drop of water and alcohol on a Petri dish. Note the time. Draw and describe the shape of each drop. How much time does it take for each to disappear? How many drops on a penny? Make a table of how many drops of water vs alcohol you can get on a penny. Do a couple of trails with different people

Consider your observations of shape of the drops. Some liquids form drops that are more round and some drops are more flat. Why do you think this is? How is the behavior of the particles in each different? Explain with words and drawings what the particles are doing to make a round or flat drop.

Discussion Suppose I am made of thousands and thousands of tiny particles. Why don’t I just fall apart like a pile of sand?

Mesmerizing Colors (E) Fill one beaker with tap water, one with cold water, and one with hot water. Let the beakers sit for a couple minutes to settle. Add one drop of food color to each. Observe what the food color does. As a group, decide on a method for showing motion. Two drawings for each temp. macro and sub-micro, that explains how the behavior of the water and food coloring particles.

Disappearing Crystals Part I Set up two cups, one with cold water and one with warm water. Let the water settle for a couple of minutes Add a tiny amount of sugar to each cup. – Same amount about the size of a watermelon seed. – Same time. – Do not shake or stir. Observe for a couple of minutes and describe what you see.

Disappearing Crystals Part II Fill a graduated cylinder with cold water. Fill a 2 nd cylinder with an equal amount of warm water. Let them settle for a couple of minutes. Prop a piece of white paper behind the cylinders so you can see the water better. Measure two tiny samples of Kool-Aid crystals, equal amounts, about the size of a grain of rice. Gently and simultaneously pour one sample into each cylinder. Watch for a couple of minutes. Describe what you see. (do not explain yet) How did the crystals behave in each cylinder? Use w ords and pictures.

Explain why the crystals seemed to disappear. Where did they go? Why did they go? Your explanation should use the idea that matter is made of particles. (Talk about particles of sugar and water.) Use words and pictures. Use the idea of particles to explain why the crystals behaved differently in cold water than they did in warm water. What must the particles be doing differently in warm water? Use words and pictures.

Mixing Liquids Follow the directions on the Mixing Liquids handout. Record your data on your Doodle Sheet #2. Explain your observations using words and drawings.

How Squishable Every person in the group must push or pull the syringe for himself/herself. You need to feel the forces and movement for yourself each time. Discuss observations as group and write down what you observed and felt. Empty syringe: – Push the plunger all the way in. – Plug the opening by covering it firmly with your thumb. – Try pulling the plunger back to about 20ml Air in syringe – With nozzle open pull about 30ml of air into the syringe – Plug the nozzle tightly so air cannot escape. Use your thumb or a large flat eraser. – With the nozzle tightly plugged, try pushing the plunger in as far as you can. Water in syringe – Push all the air out of the syringe. – Suck up about 30ml of water by pulling back on the syringe while the nozzle is immersed in water. – Remove all air bubbles and tightly plug the nozzle. – With the nozzle tightly plugged, try pushing the plunger in as far as you can. Solid pellets in syringe – Hold the nozzle so cover does not come off. – With the nozzle tightly plugged, try pushing the plunger in as far as you can

DRAW 3 boxes In each box make a drawing to show how the particles might be spaced if you could take a picture of then and greatly magnify them. How would they be spaced in a solid, a liquid, and a gas? Make each particle the same size, like this → SolidLiquidgas

What do we now know about the particle model of matter? Matter is composed of small bits, or particles. Particles are too small to see. Particles move Particles have stickiness sometimes. Depending on temperature motion changes. Colder moves slower, hotter moves faster. Particles may be attracted to other types of particles more than themselves. Faster particles have more frequent collisions with other particles so the spreading out process goes faster. Faster particles collide with more force than slower particles. Solids and liquids are packed a close as they can get. Particles in liquids can move around. (not locked in place) Gas particles have lots of space between them There is space between particles.

Particle Model Mini-Poster Make an 8.5 x 11 poster that demonstrates your understanding of one element of the Particle Model of Matter. – Select from the list in your notes. Use the entire page. Use color. Use sub-micro drawings of particles. Include a short descriptive title. Briefly explain the evidence for this part of the Particle Model.