Properties of Matter

Properties of Matter Professor Lynn Cominsky Joanne del Corral Al Janulaw Michelle Curtis NBSP Physical Science Leadership Institute June 30, 2003 Prof. Lynn Cominsky

Standard Connections • Properties of matter can be observed, measured and predicted (K) • As a basis for understanding this concept, students know that objects can be described…on the basis of physical properties such as WEIGHT • What are the common properties that scientists use to describe matter? Prof. Lynn Cominsky

First Activity: Measuring matter • How do we measure mass? • How do we know when 2 objects have the same mass? Assemble a balance. Sketch it in your notes, and label the parts of the balance. Experiment with the objects to see how the balance operates. Prof. Lynn Cominsky

Equipment for Measuring matter activity • Plastic balance • Pans • Set of random objects • Lots of washers Prof. Lynn Cominsky

Further investigations: • Does it make a difference where the objects are placed in the pans? • Does it make a difference if you switch the objects and place them in different pans? • Does it make a difference if you use a different balance? • What does it mean when we say something is in balance? Prof. Lynn Cominsky

Operational Definitions • An operational definition describes the process that is used to make a measurement • It should be able to be used by another individual to repeat the measurement process using the same (or similar) equipment Prof. Lynn Cominsky

Equipment for the mass activity #2: Questions for the mass activity #2: • Small pan balances • Standard mass sets • How do we establish a set of standard masses? • Can you write an operational definition for mass? Prof. Lynn Cominsky

Mass activity #2 • Use washers to measure the mass of an object in your set • Measure the mass of a single washer using the standard mass set • Measure the object using the standard mass set – did the results make sense? • Use the standard mass set to measure a different object • Predict how many washers it would take to balance this object – did it work? Prof. Lynn Cominsky

Thought experiment • First weigh one object, and then weigh a second object. • If you now put both objects on the scale at the same time, how will the total mass compare to the sum of your first two measurements? Prof. Lynn Cominsky

Key concepts: Mass • Mass is a property of matter that can be measured using a standard set of objects. • The typical standard that is used to measure mass is the gram. • In most everyday situations, mass is conserved. M1 + M2 = M1+2 Prof. Lynn Cominsky

Vocabulary • Equal-arm Balance: a physical instrument used to measure mass by comparing items • Mass:property of matter that describes its quantity • Gram:standard unit of measurement for mass • Standard mass set: Set of masses which have a known relationship to one another • Weight: result of gravity acting on mass Prof. Lynn Cominsky

ELD Activities: Compare • Compare and contrast masses of different objects in the classroom • Make a table with descriptions to help remember new words: Object Mass Object Description Prof. Lynn Cominsky

Publisher’s Materials • Take some time to look through the state-adopted texts to find activities relating to measuring and observing objects • Examples: HC p. C5 Prof. Lynn Cominsky

Break – some things to think about • What is the difference between mass and weight? • How would your mass change if you lived on the Moon? • How would your weight change? Prof. Lynn Cominsky

Standard Connections • Students know that objects can be described…on the basis of physical properties such as shape (K) • How do we measure volume? • How do we know when 2 objects have the same volume? • How does measuring volume compare to measuring mass? Prof. Lynn Cominsky

Third Activity – Volume of a Solid • Given: a large block and lots of smaller cubes • Use the cubes to make a model of the large block • Count the number of cubes that it takes to make your model • Repeat for several different objects • Is volume always = length x width x height? Prof. Lynn Cominsky

Fourth activity: Volume and Liquid • How do we measure the volume using a liquid? • What is the relationship between 1 cm3 and 1 mL? Equipment for Fourth activity • Graduated cylinders • Water • Plastic cubes and other objects Prof. Lynn Cominsky

Graduated Cylinders • Reading is taken by reading the bottom of the meniscus at eye level • What is this reading? Prof. Lynn Cominsky

Fourth activity: Volume and Liquid • Fill the graduated cylinder to the 35 mL mark. Drop in 7 of the plastic cubes. Measure each cube with a ruler. • How much does the water level rise? • How could you put marks on the side of the cylinder if they were not already there? • Write an operational definition for volume Prof. Lynn Cominsky

More questions about volume and mass: • How would you measure the volume of an irregularly shaped object if it was too large to fit into a graduated cylinder? • Does each gram of a submerged object displace a gram of water? • Could we measure the mass of a submerged object by the water displacement method? Prof. Lynn Cominsky

Thought experiment • Suppose a graduated cylinder is filled up to the 50 mL mark with dry sand. Then suppose that 30 mL of water is poured into the cylinder. • Will the final volume of the water and sand be measured at 80 mL? • Explain your reasoning. Prof. Lynn Cominsky

Thought experiment #2 • There are at least two volumes associated with a tin can. • What are they and how would you measure each? Prof. Lynn Cominsky

Key concepts: Volume • Volume – is measured using a standard set of objects such as uniform cubes, or by measuring a liquid such as water, which is displaced by the object to be measured • Volume is NOT conserved: V1 + V2 is not necessarily equal to V1+2 Prof. Lynn Cominsky

Vocabulary • Volume: the amount of space that an object displaces • Graduated Cylinder: A physical instrument used to measure volume of liquids (directly) or of solids (by submersion) Prof. Lynn Cominsky

ELD Activities: Analogies and Student Involvement • Draw a few circles of different sizes on the ground; tell the student the circles represent cylinders. • Then ask the students to stand in one of the circles until each circle is full. • Let them count how many students are in each circle once everyone has a place. Prof. Lynn Cominsky

Publisher’s Materials • Take some time to look through the state-adopted texts to find activities relating to measuring volume that could be used in your classroom. Prof. Lynn Cominsky

Lunch break - Things to think about Consider the two boxes shown. Their dimensions are given in meters. Answer the following questions about the boxes. Explain your reasoning. 3 Box B Box A 2 2 3 6 3 Prof. Lynn Cominsky

Lunch break questions: • Suppose these boxes, including their lids, are made of very thin plywood. Which box requires more wood? • Which box will hold more peanuts? • Which box is heavier (empty)? • Which box would you say is bigger and why? Prof. Lynn Cominsky

Standard Connections • Students know that objects can be described…on the basis of physical properties such as floating & sinking (K) • How do we measure density? • How can we tell if an object will sink or float? Prof. Lynn Cominsky

Key concepts: density • Density is defined as the mass of an object divided by its volume • Density is a characteristic property of an object: under the same conditions, all objects made of the same material have the same density • The units for density are g/cm3 – The value tells you how many grams are in one cubic centimeter of material Prof. Lynn Cominsky

Thought experiment: Density • A block of wood has a mass of 18 g and a volume of 25 cm3 • How would you interpret the number 18/25? • How would you interpret the number 25/18? • Write an operational definition for density Prof. Lynn Cominsky

Standard Connections • Students know density is mass per unit volume (8) • Students know how to calculate the density of substances (regular and irregular solids and liquids) from measurements of mass and volume (8) Prof. Lynn Cominsky

Fifth Activity: Sinking and Floating • Given: a set of objects, and a beaker of water. • Predict whether your objects will sink or float, then test out your predictions • Can you turn any sinkers into floaters? Floaters into sinkers? • Separate the sinkers and floaters into separate groups Prof. Lynn Cominsky

Fifth Activity: Sinking and Floating • What similarities are there among the objects that floated? What differences? • What similarities are there among the objects that sank? What differences? • Make a list of things that you believe influence whether or not an object can float • How will you test your ideas about sinking and floating? Prof. Lynn Cominsky

Standard Connections • All objects experience a buoyant force when immersed in a fluid. As a basis for understanding this concept: • Students know the buoyant force on an object in a fluid is an upward force equal to the weight of the fluid the object has displaced (8) • Students know how to predict whether an object will float or sink (8) Prof. Lynn Cominsky

Sixth activity: When does a boat float? • Given: little boat made of plastic cubes, aluminum foil and tape, pennies, scale, pan of water, ruler • Measure the mass of the boat • Can you use the water submersion method to determine the volume of the boat? Why or why not? • Measure the volume of the boat (including cargo space) Prof. Lynn Cominsky

Sixth activity: When does a boat float? • Calculate the average density of the boat • Given: the density of water is 1 gm/cm3 • Weigh 10 pennies, then calculate the average weight of one penny • Predict how many pennies you can add to the boat before it will sink. • Test out your prediction. • What do you conclude? Prof. Lynn Cominsky

Key concepts: Sinking and Floating • When an object is totally submerged in a liquid, it displaces a volume of the liquid equal to its volume • If the object is floating in a liquid, it displaces a volume of the liquid which has the same mass as the entire object • If you know the density of both the object and the liquid, you can calculate how much of the object is submerged in the liquid Prof. Lynn Cominsky

Math connections • An ice cube with volume of 1 cm3 has a density of 0.9 g/cm3 • It is floating in very salty water that has a density of 1.2 g/cm3 • What is the mass of the ice cube? • What is the mass of the salty water that it displaces? • What is the volume of the water that it displaces? • How much of the ice cube floats above the water? Prof. Lynn Cominsky

Cartesian Diver revisited • Can you now explain the observations that you made in this activity? • Another way to do this experiment is with a sealed packet of ketchup (that contains a trapped air bubble), rather than an eye dropper. What do you think would happen if you did this experiment at a different temperature? A different altitude? • Would the same things happen if you used the eye dropper instead of the ketchup? Prof. Lynn Cominsky

Vocabulary • Sinking: when an object is entirely covered with liquid • Floating: when only part of the object is covered with liquid Prof. Lynn Cominsky

ELD Activities: Academic Language • When someone is slow to understand, they may be called dense. Why? • When someone is feeling sad, they are said to have a sinking feeling. Why? • When someone is feeling happy, they are said to be floating on air. Why? Prof. Lynn Cominsky

Publisher’s Materials • Take some time to look through the state-adopted texts to find activities relating to sinking and floating that could be used in your classroom. • Examples: HM p. 198, HM p. C7 Prof. Lynn Cominsky

Break – puzzler • You are sitting in a boat which is floating in a small pond. Next to you, inside the boat, is a large rock. The density of this rock is 10 g/cm3. You pick up the rock and throw it over the side of the boat. Does the water level in the pond go up, stay the same or go down? Explain your answer. Prof. Lynn Cominsky

Standard Connections • Students know that objects can be described…on the basis of physical properties such as ATTRACTION TO MAGNETS • What types of materials are attracted to magnets? • How can we tell the difference between a magnet and a metal? • Are any materials repelled from magnets? Prof. Lynn Cominsky

Equipment for third activity Seventh activity: Exploring magnets • Use different magnets and bag of objects to explore magnetic properties • Magnets of various sizes and shapes • Some pieces of non-magnetized metal • Other things like rubber, wood, glass, plastic, aluminum, paper clips, etc. Prof. Lynn Cominsky

A few things to try: • Bring pairs of like and unlike magnets together at different locations • Play with magnets and pieces of metal like paper clips • Play with magnets and other materials • What common properties do objects have that are attracted to magnets? • Some things on your own! Prof. Lynn Cominsky

Key concepts • Materials that are attracted to magnets are metals • Magnets are both attracted and repelled from other magnets • Some metals are more strongly magnetic than others – iron is typically used for magnets • Some parts of the magnet (poles) are more magnetic than others Prof. Lynn Cominsky

S N Vocabulary • Magnet: material that can both attract and repel other magnets. Iron is most common. • Pole: Part of the magnet where the force is the strongest • Metal: material that is often attracted to magnets and a good electrical conductor • Horseshoe magnet: • U-shaped magnet Prof. Lynn Cominsky

ELD Activities: Visual Imagery • Make a list of objects that you have tested for magnetic properties • Indicate whether or not they were attracted to the magnet • Draw a picture of each object • Examples could include: paper clip, pencil, paper. Others? • Item Attracted? Drawing Prof. Lynn Cominsky

Properties of Matter