Unit 02 - Fundamentals of Matter
Part 01 - Properties of Matter
|
Lab - What's The Matter?
The lab to the left was performed in class. The identities of 5 different unknown substances were determined using the physical properties of those substances. (Answers - A. Iron filings, B. Baking soda, C. Calcium Chloride, D. Water, E. Glycerin) |
We can describe all matter by defining a specific set of properties of that matter. A property of matter is a characteristic that helps define a specific substance's appearance (or other observable traits) and behavior (such as chemical reactivity). If you think about it, you probably used several different physical properties in the lab above to identify the substances. I'm sure that most of you knew that tube B was baking soda and tube D was water, but how? You knew that water was colorless, had low viscosity and was oderless, right? While baking soda, you know to be a fine, white, odorless powder. These observations that helped you determine the identity of the substances are all properties of matter. We can further classify these properties as either physical or chemical.
- A physical property of matter is one that can be observed without changing the identity of the substance. Examples of physical properties include color, odor, mass, density, viscosity, and electrical conductivity. (Remember, viscosity is a substance's ability to resist flowing.) All of these properties can be easily measured without needing to react the substance with anything else.
- A chemical property of matter is one that can only be observed by reacting the substance with another substance and therefore changing its identity. Examples of chemical properties would include flammability (combustibility), toxicity and reactivity with acids or oxygen. Note that for each of these examples, a substance would need to be changed chemically in order for the property to be observed. (In order to observe how flammable Oxygen is, you would first have to ignite it, thus beginning a chemical reaction that will change the Oxygen into new products.)
|
Interactive Notebook Pg. 7 - Physical and Chemical Properties
The video to the left shows how to set up Pg. 7 of your Interactive Notebook on Physical and Chemical properties. Try to think of your own physical and chemical properties to draw on the left side. Be creative! (But make sure that you classify the properties correctly.) |
Part 02 - Classification of Matter
What is matter, anyway? You probably vaguely remember from 8th grade science (so long ago, right?!). If not, matter is anything that has mass and takes up space. Basically every tangible object is matter, including all of the rocks, planets, water, organisms and even gases (like air) in the known universe! And while matter takes many forms and can be converted from one form to another, matter can never be created or destroyed. Matter can be classified into 3 different types - elements, compounds and mixtures. An element is the simplest form of matter and is made up of atoms of a single type. Examples of elements include matter like graphite (all Carbon atoms), Aluminum and Oxygen gas. Elements can chemically combine to form compounds. A compound is a substance that is made up of atoms of two or more types that are chemically bound to one another and cannot be separated physically. Examples of compounds include water (made of hydrogen and oxygen) and table salt (made of sodium and chlorine). Elements and compounds are both pure substances. A pure substance is any matter that is made up of only one type of element or compound. So what about substances that have different elements and/or compounds mixed together.
The figure on the right shows the composition of air. You will notice that air is made up of many different elements (such as Nitrogen, Oxygen and Argon) as well as several compounds (such as Carbon Dioxide and Methane). Substances like air, that are not pure substances, are referred to as mixtures. A mixture is a system that is made up of more than one type of matter that is not chemically combined. Mixtures are different from compounds because their component parts are not chemically bound to one another. Mixtures can be classified as either homogeneous or heterogeneous. A homogeneous
|
mixture is a mixture that is uniform throughout and where every part of the mixture has the same properties. Examples of a homogeneous mixture would be saline (salt and water), Kool-Aid, and air. Brass is another example of a homogeneous solution that is made up two metals - Copper and Zinc. A homogeneous mixture of metals is known as an alloy. Homogeneous mixtures are also called solutions. Mixtures that are not uniform throughout are called heterogeneous mixtures. These mixtures are usually visibly heterogeneous. Examples include a mixture of beach sand with rocks and shells, trail mix and concrete (rocky cement).
|
Interactive Notebook Pg. 8 - Classification of Matter
The video to the left shows how to set up Pg. 8 of your Interactive Notebook on the Classification of Matter. Please remember to complete both flow charts and classify two different types of matter. Please don't use the one that I do in the video; be creative and come up with your own! |
Lab - Density of Water
The lab to the right was performed in class to determine the relationship between the mass and density of water. Based on your data, would you conclude that density is intensive or extensive? How about mass and volume? |
|
Further Describing Matter
Physical properties can be further divided between intensive and extensive properties. An intensive property is a property of matter that does not depend on the mass or size of the system. In other words, regardless of the amount of the substance that you have, its intensive properties will not change. Examples of intensive properties would include color, odor, density and electrical conductivity. Extensive properties, on the other hand, are properties that change depending on the mass and size of the system. Examples of extensive properties include mass, volume and the amount of energy stored within a substance.
Physical properties can be further divided between intensive and extensive properties. An intensive property is a property of matter that does not depend on the mass or size of the system. In other words, regardless of the amount of the substance that you have, its intensive properties will not change. Examples of intensive properties would include color, odor, density and electrical conductivity. Extensive properties, on the other hand, are properties that change depending on the mass and size of the system. Examples of extensive properties include mass, volume and the amount of energy stored within a substance.
|
Interactive Notebook Pg. 9 - Intensive Vs. Extensive
The video to the left shows you how to set up Page 9 of your Interactive Notebook which discusses Intensive and Extensive Properties. Based on your results in the Investigate - Density of Water lab, would you classify Density as an Intensive or Extensive property? |
Part 03 - How Matter Changes
|
Investigate - Steam and Ice
The lab investigation on the left was performed in class. Make sure that you take thorough observations and do your best to explain the phenomenon. |
While matter cannot be created or destroyed, it can definitely be changed. Matter is changing all around us, everyday. When you're playing basketball, your body begins to sweat. Sweat is your bodies way of cooling off since the evaporation of the moisture on your skin, causes your skin to feel cooler. And for that matter, all of the breathing that you're doing - that's chemistry too. The oxygen in the air is inhaled and used in your body where it will be converted to carbon dioxide and exhaled. And those are just a couple of the many ways that you see matter change every day! All of these changes in matter can be classified as either physical or chemical. A physical change is a change in which the identity of the substance remains the same. Examples of physical changes include changes in state of matter (like the evaporation of sweat or the boiling of water), changes in size, changes in shape, etc. A chemical change, on the other hand, is a change in which the identity of the substance changes and new substances are formed. Examples of chemical changes include the process of cellular respiration to produce CO2 (like in the breathing example above), the burning of coal, and the combustion of hydrogen (which is famously the chemical change that caused the destruction of the Hindenburg as seen
in the video to the right). While it's fine, theoretically, to differentiate physical and chemical changes by saying that chemical changes produce new products while physical changes do not, that doesn't necessarily help us determine whether a change that we see in the lab is physical or chemical. After all, how do you know that a new product has been formed? Fortunately, there are several indicators of chemical change. Usually the observation of any of the following will indicate that a chemical change has occurred:
You are probably familiar with most of the indicators listed above, with the exception of the formation of a precipitate. A precipitate is an insoluble solid that settles out of a solution. An example of a precipitate forming can be seen in the example to the right where two colorless liquids, Potassium Iodide and Lead (II) Nitrate, are reacted to form a bright yellow, insoluble solid product, Lead (II) Iodide.
A Word of Caution: Even though the indicators listed above are often associated with chemical changes, there are definitely examples where this is not the case. Bubbling for example, occurs in a liquid that is boiling, but boiling is a physical change. Energy Changes Listed as an indicator of chemical change are changes in energy. Often energy will either be absorbed or released by a |
|
chemical change. A chemical change in which energy is absorbed is referred to as endothermic while a process in which energy is released is referred to as exothermic. Typically, an endothermic change will cause the reaction vessel to feel cold to the touch while an exothermic change will cause the reaction vessel to feel warm. There are exceptions (freezing is an exothermic process and boiling is endothermic) and sometimes the energy is not thermal energy, but rather light (photosynthesis, for example, is endothermic because it requires energy from sunlight).
|
Investigate - Changes in a Bag
This lab experiment to the left was performed in class. Where the changes that occurred in this lab examples of physical or chemical changes? How do you know? Application - Physical and Chemical Changes This worksheet was assigned as homework to review physical and chemical changes as well as endothermic and exothermic reactions. Don't forget to include reasons for your answers!!! |
Interactive Notebook Pg. 11 - Physical Vs. Chemical Change
Use the video to the right to set up Page 11 of your Interactive Notebook on Physical and Chemical Changes. |
|
Part 04 - States of Matter
Of course, not all changes in matter are chemical changes. Many changes in matter are physical. One of the most commonly mistaken changes in matter are phase changes. Phase changes are changes in states of matter. The diagram to the left shows a phase change diagram. Specifically, this is known as a heating curve because it shows the relationship between heat energy, temperature and state of matter of a substance that is being heated. If a substance were being cooled, we could produce a cooling curve which would have all of the same basic features, but would have a negative slop rather than a positive one. Let's take a moment to examine the figure to the left and identify what is happening at each point. In A, our substance is in a solid state. A solid is a state of matter in which a substance has a definite shape and volume and in which the particles do not move around one another. (Note that the particles do STILL have vibrational movement, but they do not have have translational or rotational movement.) The temperature of the solid in A is gradually increasing showing that the solid is being heated. At point B, the solid has reached its melting point. The melting point is the temperature at which a substance transitions from the solid phase to the liquid phase at atmospheric pressure. (This is the temperature as the freezing point which is the temperature at which a substance transitions from the the liquid phase to the solid phase at atmospheric pressure. At the freezing point, a substance will freeze - transition from a liquid phase to a solid phase.) Note that as a substance is melting (transitioning from the solid phase to the liquid phase) its temperature remains constant. Indeed, you'll notice that the temperature will remain constant during all phase changes. This happens because the thermal energy being absorbed by the substance is being converted to kinetic energy so that the phase change can occur - in this case, the energy is being used to pull the particles out of their crystalline solid structure so that they can freely move abound as a liquid. A liquid is the a state of matter in which a substance as a definite volume, but an indefinite shape. Particles in a liquid move around more freely than the particles in a solid - they have vibrational movement as well as translational and rotatinal. Our substance has turned into a liquid by part C and the liquid is being heated. Once the liquid is heated to its boiling point (the temperature at which a substance transitions from the liquid phase to the gaseous phase at atmospheric pressure), it begins boiling (as seen in part D). When a liquid is boiling, the entire sample of the substance is simultaneously transitioning from the liquid to the gaseous phase. This is often accompanied by bubbling since the gas particles are trying to escape the liquid. However, during this process, some of the gas is again condensing to a liquid; therefore, even though all of the substance is at the boiling point, it does not all transition to the gaseous phase simultaneously. Condensation is the opposite of boiling an occurs when a gas is cooled and transitions to the liquid phase. At part E of the graph above, our substance has completely transitioned to the gaseous phase as the rising temperature indicates that the gas is still being heated. A gas is a state of matter that does not have a definite shape or volume. Gases will expand to fill their container and can thus be easily expanded or compressed. This is because much of the volume occupied by a gas is actually empty space. The gas particles move at very high speeds, colliding with each other and the walls of their container without slowing down or ever becoming attracted to them. (It is of interest to note that if the gas continues to be heated to very high temperatures, the atoms or molecules that make it up can be ionized - meaning that some of the electrons will be stripped away. This super heated, ionized, gaseous substance is electrically conductive and responds to magnetic fields. We call this state of matter plasma.)
Investigate - Phase Changes
We performed the experiment to the right in class to create a heating curve for water. Application - Phase Changes
The worksheet to the right was assigned in class as homework to practice using phase change diagrams. |
|
|
Interactive Notebook Pg. 10 - Phase Change
The video to the left shows how to set up Page 10 of your Interactive Notebook on Phase Changes. It is very important to have already completed the Investigate - Phase Change Lab in order to properly understand the left page which has an example of a Phase Change Diagram (aka a Heating/Cooling Curve). |
Part 05 - Elaborate and Review
Elaborate - Changes
The lab to the right can be performed in class to review indicators of chemical change, law of conservation of mass and physical vs chemical change. Unit 02 - Fundamentals of Matter Exam Review The unit review to the right was assigned in class to help students review for the upcoming Unit 02 exam. Please remember, that while fairly comprehensive, this review does not necessarily have all of the material that was covered in the unit. It is the students' responsibility to ensure that they are ready for the test by reviewing notes, labs, warm ups, class assignments and the review. |
|