Middleschoolchemistry.com Big Ideas about the Very Small American Chemical Society Middleschoolchemistry.com Big Ideas about the Very Small Chapter 1: Matter – Solids, Liquids, and Gases

Welcome What is middleschoolchemistry.com? Six chapters of activity-based lesson plans in chemistry-related physical science for middle school. Lessons align with state standards and the Next Generation Science Standards (NGSS). Three main goals: Help students understand and be able to explain basic chemistry concepts on the molecular level. Help students to design and conduct valid scientific experiments. Help students see the chemistry in everyday life. Composed of 6 chapters, today we are going to do an overview of chapter 1 American Chemical Society

What’s in a Chapter? Fully-developed 5-E Lesson Plans Student Reading Hands-on Activities Student Activity Sheets Multimedia Extra Teacher Background Student Reading Test Bank Also mention that we have “Extra Teacher Background” in selected lessons American Chemical Society

Goals of the Webinar Review some basic beginning-of-the-year chemistry concepts and lessons you can use from middleschoolchemistry.com (MSC) to help students investigate them. See how the philosophy and format of the MSC lessons offers flexibility in how you might use it for different teaching situations. See how MSC supports the disciplinary core ideas, science practices, and crosscutting concepts in the NGSS and state standards. Also mention that we have “Extra Teacher Background” in selected lessons American Chemical Society

Who are You and Why are You Here? A Poll What grade level do you teach? Have you used Middlescchoolchemistry.com before? Has your state adopted the NGSS and what is happening to address them? NOT about state changes In other words, why is water a liquid; why is metal a solid? American Chemical Society

A Quick Look at the Website Let’s take a quick look at the website to see a few of the main features. American Chemical Society

Lesson 1.1 Molecules Matter Engage Explore Explain Evaluate Extend What are some examples of matter? A chair A hat A mustache A rock Matter is basically stuff. How about a liquid, like water? Is water matter? How about you? Are you matter? How about a gas, like air? Is air matter? If no one says water, we should bring it up Why? American Chemical Society

A Close Look at Water Engage Explore Explain Evaluate Extend All the lessons in MSC are based on students observing some common phenomenon and trying to investigate, on the molecular level,to figure out why it happened. Students observe water on wax paper. Does the water drop stay together or come apart easily? If water was made of tiny particles (molecules), would you say they are attracted to each other or not? What else can we learn about water? What if we put food coloring in water, what could we observe? American Chemical Society

The Motion of Water Molecules Engage Explore Explain Evaluate Extend What else can we learn about the particles that make up water? Why do you think the food coloring spread out? If the food coloring is also made of particles, how could the water molecules help to spread them out? American Chemical Society

Molecular Model Animation - Liquid Engage Explore Explain Evaluate Extend Attractions keep molecules close together Molecules are in motion and move past each other Tell teachers they could have their students draw model of water on the molecular level and complete the activity sheet. American Chemical Society

Drawing a Model of a Liquid Engage Explore Explain Evaluate Extend The student activity sheet serves as the “Evaluate” for each lesson Students draw a model of water molecules and a caption to describe what their model represents. American Chemical Society

Effects of the Attractions of Water Molecules Engage Explore Explain Evaluate Extend Why do you think the water keeps its shape the moment the balloon is popped? American Chemical Society

Play a Water Game Let’s play “Water Drops Unite” & “Race Drop Raceway” Engage Explore Explain Evaluate Extend Let’s play “Water Drops Unite” & “Race Drop Raceway” American Chemical Society

Why are Water Molecules Attracted to Each Other Why are Water Molecules Attracted to Each Other? (Covered in Chapter 2 and 5) The water molecule is composed of two hydrogen atoms bonded to an oxygen atom. These are covalent bonds in which electrons are shared between the oxygen atom and the hydrogen atoms. That’s the end of lesson 1.1, now we’re going to move on to cover some other concepts from subsequent lessons in Chapter 1 But why are water molecules attracted to each other? We’ve established that molecules of a liquid are attracted and they are in motion, now let’s take a look at how temperature affects the molecules of a liquid American Chemical Society

Water Molecules Attract Each Other In the bonds in a water molecule, the electrons are not shared equally. The electrons are more attracted to the oxygen atom than to the hydrogen atoms. This makes water a “polar” molecule. Water molecules attract one another according the their opposite polar ends. This accounts for the cohesion between water molecules and gives water many of its characteristic properties. American Chemical Society

Lesson 1.2 Heating and Cooling Water Ask students: What do you think you could do to the water to make the water molecules move faster? If you wanted to test whether heating or cooling water affects the motion of the molecules, how could you do it? How would we make sure your test is fair? This is lesson 1.2 American Chemical Society

Heating and Cooling Water On the molecular level, why does heating the water affect how fast the food coloring mixes in the water? Adding or removing energy affects the speed of molecules Heating a liquid increases molecular motion Cooling a liquid decreases molecular motion ** Mention that this is from lesson 1.2 American Chemical Society

Moving Molecules Aside from moving faster or slower, what else changes about water molecules as the temperature changes? Add energy Further apart Faster motion competes with attractions End of lesson 1.2 Mention that kids make their own models by drawing pictures in each lesson Remove energy Closer together Slower motion competes with attraction American Chemical Society

Liquid Characteristics of a liquid on the molecular level The molecules of a liquid move at a certain speed at room temperature. The attractions between the molecules are strong enough to keep them close together at that speed. Why then does some water evaporate at room temperature? Well, some of the molecules DO have sufficient energy to evaporate. Remember that temperature is an AVERAGE of kinetic energy of molecules or atoms of the bulk. Adding energy (heating) makes molecules move faster causing them to move a little further apart. Removing energy (cooling) makes molecules move slower causing them to move a little closer together. American Chemical Society

Quick (very) overview of the NGSS Each NGSS standard is written as a performance expectation describing what students should be able to do at the end of a grade band. Each performance expectation attempts to integrate elements from three areas: Science and Engineering Practices Asking questions, developing and using models, planning and conducting investigations, analyzing and interpreting data,… Disciplinary Core Ideas Substances are made from different types of atoms, which combine with one another in various ways. Each pure substance has characteristic physical and chemical properties that can be used to identify it,…. Crosscutting Concepts Cause and effect, structure and function, … American Chemical Society

Middle School NGSS for Chemistry MS. Structure and Properties of Matter Performance Expectations Students who demonstrate understanding can: MS-PS1-1 Develop models to describe the atomic composition of simple molecules and extended structures. MS-PS1-4 Develop a model that predicts and describes changes in particle motion, temperature, and state of a pure substance when thermal energy is added or removed. MS-PS1-3 Gather and make sense of information to describe that synthetic materials come from natural resources and impact society. (Not addressed) American Chemical Society

Lesson 1.3 An Application of Molecular Motion in Liquids: Thermometers Students place a thermometer in hot and then in cold water. Ask students to explain, on the molecular level: Why the liquid goes up when a thermometer is placed in hot water? Why the liquid goes down in cold water? When heated, the molecules of the liquid move faster. Their faster motion competes with their attractions causing the molecules to move further apart. They have no where else to go but up the tube so the liquid rises. When cooled, the molecules of the liquid move more slowly. Their attractions compete with their slower motion causing the molecules to move closer together. As they are brought closer together, they take up less space and move down the tube. ** Mention that this is from lesson 1.3 American Chemical Society

How Thermometers Work Hot: faster, further apart, move up Cold: slower, closer together, move down When heated, the molecules of the liquid move faster. Their faster motion competes with their attractions causing the molecules to move further apart. They have no where else to go but up the tube so the liquid rises. When cooled, the molecules of the liquid move more slowly. Their attractions compete with their slower motion causing the molecules to move closer together. As they are brought closer together, they take up less space and move down the tube. In the actual activity 1.3, Kids put a thermometer in hot and cold water and then draw pictures to depict molecular motion American Chemical Society

Lesson 1.4 Molecular Motion in Solids Do the same principles that apply to liquids also apply to solids? ** Mention that this is from lesson 1.4 American Chemical Society

Heating and Cooling a Solid Ask students: If solids are also made of atoms and molecules, try to explain why this happens on the molecular level. The brass ball is an example of a solid piece of metal. It is made up of copper atoms and zinc atoms. It just barely passes through the brass ring. When heated enough, the ball does not pass through the ring. When cooled, the ball passes through the ring again. American Chemical Society

How are the Atoms of a Metal Attracted to Each Other? The atoms of a metal are attracted to one another in a way called “metallic bonding”. The outer electrons move between the metal atoms (positive ions). The attraction between the positive metal ions and the negative electrons holds the metal together as a solid. The electrons shared between oxygen and hydrogen are not shared equally Be careful, water is not an ion, it’s electrically neutral. These are areas of slight positive and negative charge and not formal charges. American Chemical Society

Solids vs. Liquids Vibrate Attracted to each other Don’t move past each other Assume that the solid and liquid are both at room temperature. Atoms very attracted to one another, vibrating in place, and not moving past one another. American Chemical Society

Heating and Cooling a Solid Hot: faster, further apart Cold: slower, closer together The brass ball is an example of a solid piece of metal. It is made up of copper atoms and zinc atoms. It just barely passes through the brass ring. When heated enough, the ball does not pass through the ring. When cooled, the ball passes through the ring again. Flexible joints in roads keep the road from cracking as it expands and contracts with changes in temperature. American Chemical Society

Solid Characteristics of a solid on the molecular level The atoms or molecules of a solid move at a certain speed at room temperature. The attractions are strong enough to keep them close together at that speed and to hold them in fixed positions as a solid. Why then does some water evaporate at room temperature? Well, some of the molecules DO have sufficient energy to evaporate. Remember that temperature is an AVERAGE of kinetic energy of molecules or atoms of the bulk. Adding energy (heating) increases the motion of the atoms causing them to move a little further apart. Removing energy (cooling) decreases the motion of the atoms causing them to move a little closer together. American Chemical Society

Gasses are Matter Too Air is made up of molecules of different gasses. It is about 78% nitrogen and about 20% oxygen. These molecules have mass and take up space. American Chemical Society

Lesson 1.5 Molecular Motion in Gases Very far apart Very weak attractions When heated, the molecules of the liquid move faster. Their faster motion competes with their attractions causing the molecules to move further apart. They have no where else to go but up the tube so the liquid rises. When cooled, the molecules of the liquid move more slowly. Their attractions compete with their slower motion causing the molecules to move closer together. As they are brought closer together, they take up less space and move down the tube. American Chemical Society

Heating and Cooling a Gas The mouth of an “empty” bottle is dipped into a detergent solution. The bottom of the bottle is placed in hot water and then in cold water. On the molecular level, why does this happen? When heated, the molecules of the liquid move faster. Their faster motion competes with their attractions causing the molecules to move further apart. They have no where else to go but up the tube so the liquid rises. When cooled, the molecules of the liquid move more slowly. Their attractions compete with their slower motion causing the molecules to move closer together. As they are brought closer together, they take up less space and move down the tube. American Chemical Society

Modeling heating and cooling a gas Outside air pressure is the same on both. The faster-moving molecules in the heated sample push harder against the air pressure and expand the bubble. The slower-moving molecules in the cooled sample push less hard against the air pressure which causes the bubble to contract. American Chemical Society

Heating and Cooling a Gas Warmer, faster moving molecules push harder from the inside against the bubble film than the air pressure pushes from the outside. Cooler, slower moving molecules don’t push as hard as the outside air pressure which pushes the bubble down. Heating the gas causes the motion of the molecules to increase. They hit the inside of the bottle and bubble film harder and more frequently. This pressure inside the bottle overcomes the outside air pressure and causes the bubble to expand. Cooling the gas causes the motion of the molecules to decrease. They hit the inside of the bottle and bubble film less hard and less frequently. This pressure inside the bottle becomes less than the outside air pressure. The pushing from the higher outside pressure causes the bubble to contract. American Chemical Society

Why are the Molecules of the Gases in Air Not Attracted to Each Other? Nitrogen (N2) and oxygen (O2) gas are made of two identical atoms bonded together. Each atom attracts the electrons of the other equally. There is no polarity like in the water molecule. Nitrogen gas (N2) Oxygen gas (O2) American Chemical Society

Gas Characteristics of a gas at the molecular level The molecules of a gas move at a certain speed at room temperature. The attractions between the molecules are not strong enough at that speed to keep them close together as a liquid or a solid; therefore, they move independently as a gas. Why then does some water evaporate at room temperature? Well, some of the molecules DO have sufficient energy to evaporate. Remember that temperature is an AVERAGE of kinetic energy of molecules or atoms of the bulk. Adding energy (heating) increases the motion of the molecules, and if they can, they move further apart. Removing energy (cooling) decreases the motion of the molecules, and if pushed on hard enough, they move closer together. American Chemical Society

Solid, Liquid, or Gas – The Big Ideas Solids, liquids, and gases are all made out of atoms or molecules (particles). These particles are in motion. In solids and liquids, the attractions between the particles keep them close together. - Fixed positions in solids and sliding past one another in liquids. In gases, the attractions are so weak that the particles do not stay near each other. Adding energy (heating) increases molecular motion, competes with attractions and particles move further apart. Removing energy (cooling) decreases molecular motion and attractions bring particles closer together. American Chemical Society

www.middleschoolchemistry.com For more resources … For more information, contact us at k8education@acs.org When heated, the molecules of the liquid move faster. Their faster motion competes with their attractions causing the molecules to move further apart. They have no where else to go but up the tube so the liquid rises. When cooled, the molecules of the liquid move more slowly. Their attractions compete with their slower motion causing the molecules to move closer together. As they are brought closer together, they take up less space and move down the tube. American Chemical Society