PhaseChange_CTS

Curriculum Topic Study: Phase Changes (link to home)
 * **Section and Outcome** || **Selected Sources and Readings for Study and Reflection** ||
 * I. Identify Adult Content Knowledge || //Science for all Americans [Chapter 4, Structure of Matter, pp. 46-49]//
 * Materials seem like they’re very different from one another, but really, all materials are made up of relatively few kinds of basic material combined in various ways.
 * modern theory of matter tells us that the elements consist of a few different kinds of atoms that join together in different configurations to make substances
 * elements have distinct properties/when elements combine, those properties may not be retained
 * every substance can exist in a variety of different states, depending on temperature and pressure
 * all but a few substances can also take solid, liquid, and gaseous form
 * when matter gets cold (the opposite is hot, NOT heat) enough, atoms or molecules lock in place in a more or less orderly fashion as solids
 * if the temperature is increased, atoms and molecules become more agitates and usually move slightly farther apart (e.g., material expands)
 * at higher temperatures, the atoms and molecules are more agitates still and can slide past one another while remaining loosely bound (liquid)
 * at still higher temperatures, the agitation of the atoms and molecules 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 (gas)
 * higher temperatures bonds break and ions are produced
 * even higher temperatures nuclei get so close during collisions that they’re affected by the strong internal nuclear forces, and nuclear reactions may occur

// Science Matters: Achieving Scientific Literacy [Chapter 8, Atomic Architecture, pp. 115-136] // NSES Grades 5-8: NSES Grades 9-12: Benchmarks Grades 3-5: Benchmarks Grades 6-8:: Misconceptions from //Atlas of Science Literacy:// Other misconceptions: ||
 * “atoms are bound by electron glue”
 * atoms can be arranged in many combinations and these combinations determine macroscopic properties
 * atomic systems will try and reach an energy minimum
 * ionic bonds, metallic bonds, covalent bonds
 * “In the ice cube, for example, the molecules of water in the crystal lattice vibrate faster and faster as heat from the outside air moves in. Eventually, they vibrate so fast that they tear loose and begin to move around freely. When this happens, the ice turns to water and we say that the cube has melted. In just the same way, molecules in boiling water move faster and faster until they lose contact with one another and enter the air as a gas.”= phase transitions
 * All phase transitions involve shifts in energy. Materials soak up heat while they melt or boil, but their temperature stays the same—all of the energy input goes into breaking up the old atomic arrangements. ||
 * II. Consider Instructional Implications || * Structure of matter may have the most implication for students' eventual understanding of the picture that science pains of how the world works.
 * Atomic theory powerfully explains many phenomena, but it demands imagination and the joining of several lines of evidence.
 * Understanding requires two key ideas:
 * All substances are composed of invisible particles
 * All substances are made up of a limited number of "basic ingredients" called elements.
 * //Benchmarks// highlights that students may struggle with the following:
 * Students might think that atoms occupy the space inside matter (fill matter up) rather than the correct idea that atoms //are// the matter.
 * Atoms are constantly moving.
 * Later adolescence is a good time to introduce atomic and molecular theory since students are then capable of abstract thought; prior to adolescence, concrete perceptions must come before abstract explanations.
 * Students need to become familiar with the physical and chemical properties of many different kinds of materials through firsthand experience before they can be expected to consider theories that explain them.
 * Ideas must be carefully developed and scaffolded for students. ||
 * III. Identify Concepts and Specific Ideas || NSES Grades K-4:
 * Materials can exist in different states – solid, liquid, and gas. Some common materials, such as water, can be changed from on state to another by heating or cooling.
 * A substance has characteristic properties, such as density, a boiling points, and solubility, all of which are independent of the amount of the sample. A mixture of substances often can be separated into the original substances using one or more of the characteristic properties.
 * The physical properties of compounds reflect the nature of the interactions amoung its molecules. These interactions are determined by the structure of the molecule, including the consituent atoms and the distances and angles between them.
 * Solids, liquids, and gases differ in the distances and angles between molecules or atoms and therefore the energy that binds them together. In solids, the structure is nearly rigid; in liquids molecules or atoms move around each other but do not move apart; and in gases molecules or atoms move almost independently of each other and are mostly far apart.
 * Heating and cooling cause changes in the properties of materials. Many kinds of changes occur faster under hotter conditions.
 * Atoms and molecules are perpetually in motion. Increased temperature means greater average energy of motion, so most substances expand when heated. In solids, the atoms are closely locked in position and can only vibrate. In liquids,the atoms or molecules have higher energy, are more loosely connected, and can slide past one another; some molecules may get enough energy to escape into a gas. IN gases, the atoms or molecules have still more energy and are gree of one another except during occasional collisions. ||
 * IV. Examine Research on Student Learning || Misconceptions from // Making Sense of Secondary Science: Research into Children's Ideas: //
 * When solids change to liquids, the mass decreases
 * Melting vs. dissolving?
 * Children do not regard a change of state as being associated with a particular temperature
 * Children are impressed with the "disappearance" of matter during evaporation, but don't understand where it goes
 * Gas is lighter than the same amount of liquid
 * During boiling, temperature continues to rise
 * When water condenses on a cold object: "Coldness changes into water"
 * OR: "Cold causes hydrogen and oxygen to make water"
 * The volume of a substance increases as its temperature rises
 * Particles get more compact when they freeze
 * Students think that water molecules are close, but not touching
 * Students have difficulty in appreciating the intrinsic motion of particles in solids, liquids, and gases, and have problems in conceptualizing forces between particles.
 * When water boils, the bubbles are filled with oxygen that separated, or air, or nothing
 * V. Examine Coherency and Articulation || * How does a map help you trace a concept or skill from its simple beginning to a culminating, interconnected, sophisticated idea?
 * The concept map (p. 59) on states of matter starts at the younger years with observations from everyday life. Then, phase changes are explored as students learn that properties of matter at a macroscopic level may differ from the things making up the large object. Then, actual molecules are “brought into the picture.”
 * What connections can you ID among concepts or skills in the topic?
 * There are nanoscopic explanations for macroscopic observations.
 * What connections can you identify to different content areas within and outside of science?
 * What prerequisite ideas can you identify for learning the topic at your grade level?
 * Molecules are perpetually in motion
 * Energy appears in different forms
 * Atoms stick together in well-defined molecules, or may be pack together in large arrays. Different arrangements of atoms into groups compose all substances.
 * Energy appears in different forms.
 * Most substances can exist as a solid, liquid, or gas, depending upon the temperature.
 * How do the “storylines” or conceptual strands in a map help you thing about the way to coherently organize the concepts and skills in a topic? ||

[Chemistry 6.3] "Using kinetic molecular theory, describe and contrast the properties of gases, liquids, and solids. Explain, at the molecular level, the behavior of matter as it undergoes phase transitions." [Physics 3.3] "Describe the relationship the average kinetic energy and temperature. Recognize that energy is absorbed when a substance is changed from a solid to a liquid to a gas. Energy is released when a substance changes from a gas to a liquid to a solid. Explain the relationships between evaporation, condensation, cooling, and warming."
 * VI. Clarify State Standards and District Curriculum || Massachusetts

Michigan [C3.3] "Heating impacts: heating increases the kinetic (translational, rotational, and vibrational) energy of the atoms composing elements and the molecules or ions composing compounds. As the kinetic (translational) energy of the atoms, molecules, or ions increases, the temperature of the matter increases. Heating a sample of crystalline solid increases the kinetic (vibration) energy of the atoms, molecules, or ions. When the kinetic (vibrational) energy becomes great enough, the crystalline structure breaks down, and the solid melts." [C4.3c] "Compare the relative strengths of forces between molecules based on the melting point and boiling point of the substances." [C4.3A] "Recognize that substances that are solid at room temperature have stronger attractive forces than liquids at room temperature, which have stronger attractive forces than gases at room temperature." [C4.4a] "Explain why at room temperature different compounds can exist in different phases." [C5.4c] "Explain why both the melting point and boiling points for water are significantly higher than other small molecules of comparable mass (e.g., ammonia and methane)." [C5.4d] "Explain why at room temperature different compounds can exist in different phases." [C5.4e] "Compare the melting point of covalent compounds based on the strength of IMFs."

California [Chemistry 7c] "Students know energy is released when a material condenses or freezes and is absorbed when a material evaporates or melts." [Chemistry 7d] "Students know how to solve problems involving heat flow and temperature changes using known values of specific heat and latent heat of phase change." [Grade 8 3d] "Students know that states of matter (solid, liquid, gas) depend on molecular motion." [Grade 8 3e] "Students know that in solids the atoms are closely locked in position and can only vibrate; in liquids, the atoms and molecules are more loosely connected and can collide with and move past one another; in gases, the atoms and molecules are free to move independently, colliding frequently." [Grade 8 5d] "Student know physical processes include freezing and boiling in which a material changes form with no chemical reaction." ||