9C.2.1.4 Matter
Use kinetic molecular theory to explain how changes in energy content affect the state of matter (solid, liquid and gaseous phases).
Use the kinetic molecular theory to explain the behavior of gases and the relationship among temperature, pressure, volume and the number of particles.
Overview
Minnesota Standard in Lay Terms
- The motion of particles determine the state of matter: high = gas, medium = liquid, low = solid.
- The kinetic molecular theory describes and explains the behavior of gases. High temperatures cause particles to move faster which increases collisions and causes an increase in pressure or volume.
Big Idea
Matter consists of extremely tiny particles that cannot be seen with a light microscope, that are constantly in motion, and the interactions between these particles explains the states of matter and how matter changes with temperature.
- Every substance can exist in a variety of states depending on temperature and pressure.
- When matter gets cold enough, particles lock in place in a more or less orderly state as solids.
- Increasing the temperature means increasing the average energy of motion of the particles.
- As the temperature is increased, the particles become more agitated and usually move slightly further apart causing the material to expand.
- At higher temperatures, the particles are more agitated and can slide past each other while remaining loosely bound as a liquid.
- At still higher temperatures, the agitation of the particles overcomes the attractions between them and they can move around freely, interacting only when they happen to come very close, usually bouncing off one another as a gas. (Science for All Americans - pp. 47-48)
Solid | Liquid | Gas |
Particles are close together | Particles are close together | Much further away than in solid or liquid form |
Limited in motion and vibrate in place | Always disordered | Always disordered |
Cannot move past or around each other (fixed position relative to each other) | Greater freedom to move than in a solid | Move freely with a range of speeds |
| Can slide past one another and move with a range of speeds | Sometimes collide with each other and bounce off |
MN Standard Benchmarks
9C.2.1.4.1 Use kinetic molecular theory to explain how changes in energy content affect the state of matter (solid, liquid, and gaseous phases).
9C.2.1.4.2 Use the kinetic molecular theory to explain the behavior of gases and the relationship among temperature, pressure, volume, and the number of particles.
"A Framework for Science Education" (preliminary draft), National Research Council (NRC)
- "PS1: Macroscopic states and characteristic properties of matter depend on the type, arrangement and motion of particles at the molecular and atomic scales," p. 3-10
- also review PS1.B.: "How can you distinguish one substance from another?"
"Science Curriculum Topic Study Guides," "Matter," pp. 157-173
- Behavior and Characteristics of Gases (p. 159)
- Classifying Matter (p. 162)
- Liquids (p. 166)
- Particulate Nature of Matter (p. 169)
- Physical Properties and Change (p. 170)
- Properties of Matter (p. 171)
- Solids (p. 172)
- States of Matter (p. 173)
- Physical Science - Content Standard B (essay page 177 for development of)
- Structure and Properties of Matter (paragraph 5, p. 179)
- Conservation of Energy and the Increase in Disorder (p. 180)
Benchmarks of Science Literacy
- Physical Setting: Structure of Matter, pp. 76-79
- Most substances can exist as a solid, liquid, or gas depending on temperature. 4D/M8** (SFAA)
- Research Base: Structure of Matter, pp. 336-337
American Association for the Advancement of Science Atlas
"Making Sense of Secondary Science; Research into Children's Ideas"
- Chapter 9: Solids, Liquids and Gases (pp. 79-84)
- The authors help you to understand the ideas-right and wrong-that your students have already developed, and to teach in a way that takes their learning perspectives into account.
From "Science Framework for the 2009 National Assessment of Educational Progress, Physical Science," pp. 25-38:
Inquiry, evolution, and kinetic molecular theory are three "big ideas" of the natural sciences. Students' understanding of these ideas develops across the K-12 experience. However, the big ideas typically appear explicitly in standards, test frameworks, and assessments only late in the K-12 sequence. So, for instance, "understanding kinetic molecular theory" typically appears in grade 9-12 standards and on assessments administered at grade 12. However, components essential to the understanding the theory develop early in school science. Children observe water "disappearing," from a pan being heated on the stove and water droplets "appearing" on the outside of glasses of ice water. They notice the relationships between warm and cold and the behavior of water. They develop models of water, warmth, and cold that they use to make sense of their observations. They reason that the water on the outside of the glass came from inside the glass. But their reasoning is challenged by the observation that droplets don't form on a glass of water that is room temperature. Does the water really disappear? If so, where did the water droplets come from when a cover is put on the pot, and why doesn't the water continue disappearing when the cover is on?
These observations, models of matter, warmth and cold, are foundations of the sophisticated understandings of kinetic-molecular theory. Water is composed of molecules, they are in motion, and some have sufficient energy to escape from the surface of the water. This model of matter allows us to explain the observation that water evaporates from open containers. Understanding temperature as a measure of the average kinetic energy of the molecules provides a model for explaining why the rate at which water evaporates is temperature dependent. The higher the temperature of water the greater the rate of evaporation. This simple description illustrates that at different points along the learning continuum the understandings and abilities that need to be assessed are fundamentally different.
Common Core Standards
2010 Literacy Standards - Reading Benchmarks: Literacy in Science and Technical Subjects 6-12
Misconceptions
("Benchmarks for Science Literacy: 4d The Structure of Matter" pp. 336-337)
- K-8 students may think everything that exists is matter (heat, light, electricity).
- Students may think some matter is weightless.
- Students may think atoms fill matter up rather than atoms ARE matter.
- Students may have trouble with the idea that atoms are in constant motion.
- Students are very committed to a theory of continuous matter, not yet understanding that a solid is a combination of separate particles making up that solid.
- Students lack an appreciation of the very small size of particles and that there must be something between all particles.
Vignette
Ms. R. has a series of stations set up in the laboratory for her students to explore the behavior of gases, and how temperature, pressure, and volume affect one another in a sample of a gas. At each station, students are asked to experiment with one of these variables: pressure, temperature, or volume. Students predict what they think will happen and then observe what does happen as they work at each station.
The following day, students get into pairs and collaborate to come up with explanations for why they saw the results they recorded, write the explanations onto a paper, and then exchange the papers between groups. A class discussion follows as the groups try to determine how pressure and temperature affects the behavior of gases.
Ms. R. takes the experience the students have just had to teach the gas laws to the class. (With the higher level students, it would be reasonable for them to derive the gas laws with some guidance.) She encourages students to think of times when they have seen the gas laws in their daily lives. During the next class period, Ms. R. has the students choose and read articles from "Chemmatters - Articles on Solids, Liquids and Gases" and answer questions as well as develop several questions of their own (see site below to help identify possible choices).
To introduce the new idea of particles (moles) into the picture, Ms. R. uses the "PhET Interactive Simulations" computer simulation on her interactive whiteboard. Once students understand how to use the simulation tools, Ms. R. has them collect and graph volume, pressure, temperature and number of particles data to illustrate the various gas laws and how a sample of gas can vary in behavior depending on the sample size. As a check for understanding, students are given several short answer questions asking them to explain the results they saw during the introductory activity - does this agree or disagree with their initial ideas? Students are encouraged to keep in mind: What is the evidence of your explanation? How good is your evidence? What specifically supports your conclusions? What else do you need to know?
Demonstrations and/or inquiry activities (see The Practice of Science Standards) such as showing that a mylar balloon containing air stays inflated while one filled with helium will deflate over time, what happens when boiling water in a vacuum chamber, or causing a hard-boiled egg to be pushed into a cider jug, etc. all provide opportunities for discussion and clarification about the behavior of gases and the particle nature of matter. Ms. R. builds time into the week for student group discussion and processing. For students who struggle with the very abstract concepts in chemistry, this becomes a great place to make the topic tangible. Ms. R. gives a weekend homework for students to find moments when they see gases behaving or "misbehaving" according to what they have been learning. The following Monday, students are given an opportunity to share their experiences. (Benchmark 9.1.1.2.2)
Later in the unit, Ms. R. has the students perform the "Molar Volume of a Gas Lab" using the Vernier gas pressure sensor and temperature probes. Students are able to collect three data samples to determine the molar volume of a gas at STP. (A gas collection tube can be used, but this method will take a full 50 minutes for one data set and it can be difficult to get accurate results.) The second day of the lab, pairs of students work together to determine how to analyze the data to determine the molar volume of a gas. As the students work, Ms. R. walks throughout the room helping students determine what data they have and what they are looking for using unit analysis. Once students determine the experimental value, Ms. R. supplies them with the theoretical value and the class discusses why there is a difference and how this difference might be minimized next time. Students begin to understand how scientists use data to look for patterns, determine the value of constants, and realize that constants are not just magic numbers teachers pull out of a top hat! (See: Nature of Science and Engineering Strand: standard 4 - Science, technology, engineering and mathematics rely on each other to enhance knowledge and understanding.) (Benchmarks 9.1.3.4.2-9.1.3.4.6)
Resources
Suggested Labs and Activities
- Inquiry lab on gas behavior works well as stations. Simple demonstrations that kids can do themselves - card on a cup of upside-down water, imploding a can, boiling water with ice, etc. (Benchmark 9.1.1.1.2)
- Simulation for behavior of gases. This simulation illustrates all of the gas laws and can help students determine the relationship between the variables of volume, temperature, pressure, and the number of particles. (Benchmark 9C.2.1.4.2)
- Simulation of states of matter with teacher lesson plans and tips from design team. This site can help students understand the relationships between the structure and properties of matter and the interactions of energy and matter (e.g., phase change, equilibrium). It can also help the student to describe the three normal states of matter (solid, liquid, gas) in terms of energy, particle motion, and phase transitions. (Benchmark 9C.2.1.4.1)
- Both of the above simulation sites could be used for introductory inquiry by the students, as well as a review where students would predict results and check for accuracy.
Instructional Suggestions/Options
- Gases are an excellent topic to engage the kids each day with a simple demonstration. You might even have the students volunteer to do a demonstration of their own.
- NSTA series of Formative Assessment Probes
- Uncovering Student Ideas in Science, Volume 2, pp. 65-70
- "What's in the Bubbles?"
- Uncovering Student Ideas in Science - Volume 3, pp. 25-31
- "Is it a Solid?"
- Uncovering Student Ideas in Science - Volume 3, pp. 45-50
- "Hot and Cold Balloons"
- Helpful Tips
- concrete perceptions must come before abstract explanations
- students must become familiar with these ideas through firsthand experience
- Scope and Sequence
- The Video: FLUBBER can be used as an interesting way to have students see matter and how different properties can vary. If science changes the properties of matter, what can happen?
- "World of Chemistry," look for the archived article: "Science Literacy - Chemmatters: Science of Snowflakes;" questions are also available in the teacher's guide.
- "Topic 7: Gases" Learning4Mastery.com; podcasts for students available in 15 minute clips.
- Using a classroom set of small whiteboards can help an instructor check for understanding. Having students sketch the graph of direct and inverse relationships as gas laws are studied is a good method of formative assessment if clickers are not available.
Vocabulary/Glossary
- Gas: a phase of matter that has an indefinite shape and an indefinite volume. The atoms or molecules in a gas are not bonded together and are able to move freely.
- Kinetic energy: motion of particles
- Liquid: a phase of matter that has an indefinite shape, but a definite volume. The atoms or molecules in a liquid are bonded together, but the bonds are continuously breaking and re-forming.
- Matter: anything that has mass and takes up space
- Motion: change in position of an object with respect to time
- Particle: has mass and volume
- Physical change: a change that alters one or more physical properties of a substance, but does not alter the identity of the substance. Examples include freezing, boiling, bending, crushing, etc.
- Physical property: a property or characteristic of a substance that can be measured or observed without changing the identity (chemical composition) of the substance. Some examples include boiling point, melting point, density, size, shape, etc.
- Plasma: a phase of matter in which the amount of heat energy available is larger than the ionization energy of the atoms. This means electrons are continuously escaping and re-attaching, resulting in a sea of highly charged particles. Plasmas exist only at very high temperatures, such as those found in stars.
- Solid: A phase of matter that has a definite shape and definite volume. The atoms or molecules in a solid are rigidly bonded together.
- State (phase): the physical form of a sample of matter; solid, liquid, gas, or plasma
- Online videos can be a great way to engage students at the start of a unit. A Google search of gas laws and/or states of matter can yield a variety of demonstrations.
- This site has a series of videos in one place showing several gas laws in action. It could be used to replace demonstrations if materials are not available, as well as a fun review activity. (Benchmark 9C.2.1.4.2)
- These videos are not modern but give a good foundation of basic information after the class has had some experience with states of matter and gases. They can be used as a summary of the unit or possible review; have students write several questions that come to mind as they watch. Worksheets are also available. (Benchmark 9C.2.1.4.1)
- Vernier Labs for Chemistry is the general site for all things Vernier. If you are just beginning to use digital collection tools, look at the starter kit that Vernier offers.
- "Molar Volume of a Gas" by Vernier. This lab uses both pressure sensor probes and temperature probes. A gas eudiometer, millilgram balance, and barometer can be used if probes are not available.
- Boyle's Law Lab by Vernier. For this lab you will need the pressure sensor probes along with the data collection device.
- PhET simulation site offers various simulations to explore states of matter and gas behavior. Works very well as a demonstration on an interactive white board.
MN Math Benchmarks
- 9.3.1.3 Understand that quantities associated with physical measurements must be assigned units: apply such units correctly in expressions, equations, and problem solutions that involve measurements (gas law formulas); convert between measurement systems (Celsius to Kelvin temperatures).
- 9.3.1.5 Make reasonable estimates and judgments about the accuracy of values resulting from calculations involving measurements.
- 9.4.1.3 Use scatter plots to analyze patterns and describe relationships between two variables. Using technology, determine regression lines and correlation coefficients; use regression lines to make predictions and correlation coefficients to assess the reliability of those predictions.
- The gas laws could be used to meet partial benchmarks in the algebra standard including linear relationships and calculator use.
Additional Resources
- Flinn Topic Labs are a great sets of labs by topic. Fairly inexpensive. Many are published separately on the monthly email newsletter from Flinn.
- This site has 15-minute podcasts for every topic in a general chemistry course. They are 15-minute segments posted on Youtube for students to use independently or as a tutorial supplement for classroom instruction.
- "ChemTours" developed specifically for Chemistry, 2nd Edition. These use animation and interactive exercises to help develop your understanding of fundamental concepts.
- Mark Bishop's Online Chemistry Textbook includes lessons, Powerpoints, and tutorials along with typical written text.
- From Modern Chemistry, by Davis & Metcalfe:
- From Chemistry, by Wilbraham, Staley, Matta & Waterman:
- From Chemistry: Science in Context, by Gilbert, Kirss, Foster & Davies:
- Online Tutorials for all topics: W.W. Norton and Company
Assessment
Assessment of Students
Questions for assessing knowledge (answers are bolded)
1. Which of the following factors affects the pressure of the gas in a balloon?
a. temperature
b. volume
c. number of particles
d. all of the above
2. A gas has
a. a definite volume but no definite shape.
b. a definite shape but no definite volume.
c. no definite shape or definite volume.
d. a definite volume and definite shape
3. The volume of a gas collected when the temperature is 11.0°C and the pressure is 710 mm Hg measures 14.8 mL. What is the calculated volume of the gas at 20.0°C and 740 mm Hg?
a. 7.8 mL
b. 13.7 mL
c. 14.6 mL
d. 15 mL
4. Which of the following best accounts for the compressibility of a gaseous substance?
a. high average kinetic energy
b. great average distance between the molecules relative to their size
c. weak intermolecular forces
d. the relatively low molecular mass of most gases
5. How can a person increase the volume of a balloon without adding blowing more air into it?
Lower air pressure outside to make pressures unequal therefore expanding balloon. OR Heat the balloon so particles increase in speed, increasing collisions therefore expanding balloon.
6. A teacher places a beaker of water into a vacuum chamber and turns it on. The water begins to boil. What will the temperature of the water be? Explain.
The water will remain at room temperature. Since the pressure above the water decreases, the vapor pressure within the liquid becomes greater letting the particle escape through boiling.
Assessment of Teachers
1. During a demonstration, a candle is lit in a small pan of water and a glass is placed over the candle. The flame goes out and the water level rises. A student explains the rising water by explaining the oxygen is burned up so the volume of gas decreases so the water rises. How do you clarify the student's incorrect reasoning for the water rising?
A good way to examine this idea is to do a calculation of the percent oxygen in air and the volume it would take up in the cup and whether it would cause the difference in height. Showing them the hard-boiled egg in a cider jug is similar and helps illustrate the idea of cooling air lowering pressure.
For certification in the content area, there is an online practice area for teachers for the PRAXIS chemistry test. The topics listed under the kinetic molecular theory include: description of an ideal gas, molecular speed and kinetic energy distribution, gas laws, real gases.
Differentiation
Struggling and At-Risk
- Using demonstrations daily can engage most students and seeing them invites students to attend class regularly. Gases can be a real gas for them.
- Rearranging formulas can be very difficult when solving gas problems. Arranging them in a linear fashion (PVT = PVT) is easier than having a fraction in the formula. Isolating a single variable from this point is less complex.
- Memorization is hard for them - using real life examples they come up with can help bring back the relationships talked about during class.
- Teaching Science to ELL, parts 1 and 2: NSTA journal The Science Teacher articles available for free on ELL language and learning.
- The Sourcebook for Teaching Science - Strategies, Activities, and Instructional Resources. From the website: "The science classroom is often a frustrating place for English language learners. Science has a complex vocabulary that is difficult even for native English speakers to learn. Difficulty learning English should not be confused with an inability to think scientifically. Many of the strategies that are useful for English language learners are effective for differentiating instruction for other students as well." On this webpage, the author references ELL strategies and activities that are found throughout the book.
- Teaching Science to English Language Learners: Building on Students' Strengths. From the NSTA description: "Can a student's cultural background support learning in science? Or is concentrating on the specialized vocabulary of science the best way to help English language learners learn science? This book addresses these and other pressing questions you face when working with students whose linguistic and cultural backgrounds, as well as their languages, are different from your own."
- More frequent quizzes over smaller amounts of materials.
- Cornell system of notes
- Foldables for vocabulary and formulas.
- Charts can be a valuable, visual tool.
Solid | Liquid | Gas |
Particles are close together | Particles are close together | Much further away than in solid or liquid form |
Limited in motion and vibrate in place | Always disordered | Always disordered |
Cannot move past or around each other (fixed position relative to each other) | Greater freedom to move than in a solid | Move freely with a range of speeds |
| Can slide past one another and move with a range of speeds | Sometimes collide with each other and bounce off |
Parents/Admin
Administrators
- Students should be actively engaged in various labs demonstrating the idea how gases behave in different conditions. Loud "popping" would not be unusual. Administration should expect to see student work that uses reasoning of how volume, pressure and temperature relate to different states of matter and its behavior.
- Safety is crucial; the danger may not be chemical, but gases under pressure as well as hot water can do significant harm.