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LESSON PLAN : METALLIC BONDINGCourse: ChemistryGrade level: 10th gradeUnit Number: 3Unit: Chemical Species and Their Interactions The section in the curriculum: 3.2.6Topic: Metallic BondingAllocated time: 2 x 45 hours = 90 minutesLearning outcome (objective): Explains the formation of metallic bonding.Make connections between the structure of metallic bonding and the properties of metals.Prerequisites: The structure of atomic model (Valence electrons)Chemical species ( metal, nonmetal)Delocalized electrons The mechanism of bonding (Ionic bonding)Concept Lists: electrostatic attractions sea of electron metallic bond alloys malleability ductility electrical conductivity thermal conductivity Materials and equipments needed: 10 – 15 balloonsExperiment: beher glass, silver plate, copper plate, iron plate, ice and hot watervideos and animationsFlow of the lesson from the beginning to the end in a detailed step by step manner (Content with all the activities and procedures):1st LECTURE HOUR (45 min.)INITIATION/OPENING (7 min.)Concepts: sea of electronmetallic bondEntrance: Greeting Because balloons take the student’s attention we preferred to start with a student activity before reminding previous lessonAttendance while making student activity to prevent time consumingBalloon ActivityBalloon Activity (5 min.)Before explaining the aim of the activity, let us explaining the activity in order to make it meaningful for you in understanding our aim.Balloon activity: Give students inflated balloons. Each of the students is an atom of some metal.(e.g. gold) Each of the balloon is an electron belonging to that atom. Each student tosses her/his electron freely from hand to hand into the air and gently hits other electrons that are in the air, much like a volleyball game with many balloons being used instead of one ball. Everybody wants to play with the balloons, so this keeps the atoms together. Aim of the Student ActivityThis activity will serve as an analogy for metallic bondingAt the end of the first lecture students will make connection between metallic bonding and the balloon activity.During ActivityWhile giving balloons to students, they probably wonder why teacher let them playing with balloons and so, teacher says: “We will make a connection between our topic and this activity at the end of the lecture.”During the activity teacher won’t make any extra explanation about the aim of this activityThe TopicAfter finishing the activity, teacher says: “We know how metal and nonmetal come together, we learned how nonmetal and nonmetal come together; what about metal and metal?”The aim of this question is not really asking students to explain their ideas but just informing students about what will they learn in this lecture roughly. MAIN BODY OF THE LESSON (30 min.)Review of the last lesson (10 min.)After informing students about the topic, teacher starts with review of the last lesson Aim: reminding ionic bonding forms a basis for better understanding of metalic bonding. Because comparing metallic bonding with a type of bonding that students are familiar with provides students with making connections between new and old knowledge.Teacher says “Let’s remember what the ionic bonding is first to understand metallic bonding better.”Teacher asks “Do you remember how does ionic bond form?”Expectation: We expect students to remember:metal~ nonmetal “e-” transfer because of octet rule“+” and “-” ion formationIf students cannot remember, teacher asks some guiding questions: metal~ nonmetal: “ Between which kinds does ionic bonding formation occurs?” octet rule/ “e-” transfer “+” and “-” charges: “We know that elements are found as their most stable forms in the nature. For example O is seen in the form of O2. So, do you remember how an element become more stable?”(sharing/ transfer of e- (*) )Video: Ionic BondingAfter taking students respond, teacher says: “Let’s see a video simulation showing the formation of ionic bonding.”Video (Ionic Bonding)Teacher makes explanation while showing video. Ionic Bonding --> Metallic BondingAs you know metals tend to give their valence electron instead of taking more electron because they have more empty orbitals then full orbitals,So, they tend to be “+” charged.Teacher asks: How do you think that metals and metals form a bond?”“How do they look like?”STUDENTS’ MISCONCEPTIONABOUT METALLIC BONDINGMISCONCEPTIONS ABOUT THE STRUCTURE OF METALLIC BONDINGCations without mobile electronsUnique motion of atoms with their corresponding electrons( atoms and their corresponding electrons move together such that its electrons move only in a certain place)In metal the electron are covalently bonded (Taber 2003)Metals have bonding similar to ionic because there is positive and negatives (Taber 2003) There is no bonding in pure metals (Taber 2001)“Why atoms of metals do not repel each other while all are positively charged? / How can atoms of metals stay together whilethey are positively charged?” Ionic Bonding Metallic BondingPossible Students’ PredictionsTeacher writes the predictions on the board:It can’t be possibleThey can stay together via attractionThey can stay together with the help of electrons Sea of Electron Video Strong side: We preferred this animation because it was the only simulation that shows the movement of both electrons and cations Weak side: It is not clear whether the electrons are valence electrons or both inner and outer electrons Teacher Explanationan array of metal cations in a "sea" of valence electronsThe electrons are confined to the metal by electrostatic attractions to the cations, and they are uniformly distributed throughout the structureThe valence electrons are mobile, and no individual valence electron is confined to any particular metal ionAlloysTeacher says “We learned the structure of metallic bonding within metal” “Can we form a substance composed of two different metals?”Expectation: We don’t expect students to give detailed explanation. But some students will probably heard about alloys before from daily life. Teacher says:“Have you ever heard about bronze medal from olympiads?”Expectation:Students probably say yes.Coin Steel (Iron- Manganese and some other elements)Brass( Copper- Zinc)Pewter ( Lead- Tin) “These are called as alloys and alloys are mixture composed of at least 2 different metals.” All ingredient substance are melted separately then mixed while they are liquid in certain amounts.When they get cooler they become homogeneous solid. CLOSURE OF THE LESSON (8 min.)Analogy (Baloon Activity)Aim: Providing students with a chance of explaining the metallic bonding with their own words.To assess students’ level of understanding within the lesson. At the end of the first lecture, teacher asks students to define the similarities between metallic bonding and this activity. Teacher asks:“How can we make connection between metallic bonding and baloon activity in the light of things that we learned?” Expectation:We expect students to explain that they represent some atoms of metalWe expect students to explain that balloons represent electrons belonging that atomsWe expect students to explain that moving balloons resemble the sea of electron in the metallic bonding. If students are not able to see the similarities between metallic bonding and balloon activity we will ask more guiding and specific questions:“What may balloons represent in the balloon activity in terms of metallic bonding?”“What may students represent in the balloon activity in terms of metallic bonding?”2nd LECTURE HOUR (45 min.)Concepts: electrostatic attractionsmalleabilityductilityelectrical conductivity thermal conductivityINITIATION (5 min.)Explanation of the Topic:Teacher says:“We learned the structure of metallic bonding.”“So, what can be the properties of metals regarding of the structure of metallic bonding?” Expectation: The aim of this question is informing students about the topic of the lesson.MAIN BODY (30 min.) Explaining malleability property of metals by using animation and by explaining some important points of the subject. Teacher explanations are below:As you see the atoms were shifting, did not break apart.“Why would it that be the case?”Because the delocalized electrons are always there. Any shifting positively ions are going to be hold together by attraction to the constant presence of those valence electrons that sea of electrons. Delocalized electrons: Electrons belonging to certain molecules are not attached to a particular atom or bond in that molecule. These electrons are said to be "delocalized" because they do not have a specific location (are not localized) Teacher asks students to give daily life examples for the malleability of metals.Teacher asks:“ In where this property can be used in daily life?”Expectation: We expect students to give some examples of malleability from daily life because there are numerous examples from …. To a very complicated piece of an electronic mechanism.Explaining ductility property of metals by the help of a video.Teacher asks:“What about a wire?”Expectation: Students will again probably think that it is because of malleability. Teacher says:“ But can we get a wire by applying compressive force on a metal?”“ What other kind of force can be applied on a metal to get a wire?”Expectation: We don’t expect students to answer these questions. We just want make them thinking on.Teacher says:“ Let’s watch a video to find answers of these questions.” VideoAim: Teaching ductility by comparing the malleability and ductility of a metal at particular level.Strong side: It explains malleability and ductility at particular level.Weak side: Sea of electrons are not represented at the mean while applying force.After video, teacher explains ductility which is a solid material’s ability to deform under tensile forceTeacher asks :“ Which one the wires in the pictures represents the better ductility of a metal?” by showing two pictures. Teaching the thermal conductivity by an experiment.Aim: to explain thermal conductivity by comparing the thermal conductivities of three different metals Ag, Cu, and Fe.We intentionally choose 3 different metals because we will want students to write a journal about the reason of 3 different rates of thermal conductivities.Activity will be done by grouping students. Each group will consist of 3-4 students.VideoThis video will not be shown in the class during lesson but indicated experiment in the video will do by students.Explaining the electrical conductivity of metals by using video simulation.Teacher says:“Another property of metals is electrical conductivity.”Video simulation Teacher says:“As in the thermal conductivity, the motions of delocalized electrons conducts the electricity as well.” “Electrical current flows easily through the moving electrons in the sea of electrons.” Explaining the metallic lustre by asking question.Teacher ask:“How can metals look like so shiny?”Expectation: We don’t expect students to give the detailed answer, but they may state that metals reflect the light.Teacher says:“ Valence electrons in the sea of electrons are free to wander throughout the material with little resistance.”“ When light shines on metal, it sets these free electron into vibration.”“Instead of energy springing from atom to atom, it is reemitted as visible light.”CLOSURE (10 min.)Teacher gives a worksheet containing multiple choice and true/false questions to students to assess students’ understanding of metallic bonding.Worksheet1.Metallic solids are solids made entirely of _________. A: ionic bondsB: covalent bondsC: one metallic elementD: multiple metallic elements2.True or false: Metals give up electrons easily. A: TrueB: False3.In metal solids, the _____________ electrons form a shared electron cloud. A: innerB: middleC: valence4.Because the electrons in a metallic solid are ________, the metal can be bent into shapes or drawn into wire. A: mobileB: stableC: rigid5.What is it called when a metal can be drawn into wire? A: malleabilityB: ductility6.Because of the mobile electron clouds in metallic solids, metals can conduct electricity. A: falseB: true7.What is it called when a metal can be hammered or bent into shapes? A: malleabilityB: ductility8.Because of the mobile electron clouds, metals cannot conduct heat. A: TrueB: False? ? 9.What does the 'sea of electrons' contain? A: All the electrons in that metal. B: The electrons in the outer shell of that metal. C: The electrons in the inner shell of that metal. ? 10.Why are metals able to conduct electricity? ? A: The positive metal ions pass charges to each other. B: Electrons pass charges through the positive metal ions. C: The sea of electrons helps pass charges through the metal. 11.Metallic bonding describes the bonds between two metals. A. True B. False ASSESSMENTTeacher asks 2 open ended questions as homework. Due date is next lesson.What can be the reason of different rates of thermal conductivity of different metals? Do you think that all metals shine in the same amount? Explain.Method/s of evaluation and assessment tools to be used: worksheetResources/references: (All the handouts, worksheets, quizzes, exams, slides, video snapshots, visulas, web page links of visulas/animaions/simulations, homeworks, assignments, etc. will be attached here. How will these resources be used will be explained in “flow of the lesson” section): ................
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