Warm-up With your table partners…. Read each others conclusion Use the rubric (green sheet) and critique your partners conclusion. – Things they did well – Things that are missing or incomplete

Unit 1 Physical Properties of Matter Part 1 – Particle Model

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 It? Get These paper plate samples of substances scooper Do This 1. Decide in your group on what properties to look at. 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. 2. Look closely at these properties for each of the substances. If you have an idea of something you’d like to try, just ask. 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 4 samples

Can You Describe It? Column E: What happens when you add a small amount of substance to a a couple mls of water Column F: What happens when you add a small amount of substance to a couple mls of vinegar. Final column: What is it? Name as many substances as you can based on the evidence from your observations. What other properties could you have investigated with the correct equipment?

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. 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?

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.

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.

Swab the Deck 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?

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. Draw the group ideas on a white board.

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.

Mixing Liquids Follow the directions on the Mixing Liquids handout. Change 50 ml to 30 ml Explain your observations using words and drawings.

Consolidate Your Thinking For each activity: – Title – Observations: Clear, accurate (drawings and words) – Explanation: Molecular level drawing using particles to account for what you observed Logical connection between observations and explanation Discuss your ideas and be able to account for all observations using particles.

Particle Model of Matter (What do we know?)