Teaching objectives of the teaching plan of chemistry "Chemical properties of metals" in the second volume of ninth grade of People's Education Press.
Knowledge and skills
1. Understand the reaction phenomenon of common metals such as iron, aluminum and copper with oxygen.
2. Understand the displacement reaction of common metals with hydrochloric acid and sulfuric acid and with salt solution; Displacement reaction can be used to explain some chemical problems related to daily life.
Process and method
1. Understand the basic process of scientific inquiry and be able to carry out preliminary inquiry activities.
2. In class, teachers organize, guide and guide students to understand the chemical properties of metals through experimental exploration and discussion.
3. Initially learn to use observation, experiments and other methods to obtain information, and can use charts and chemical language to express relevant information.
4. Initially learn to use comparison, induction, generalization and other methods to process the obtained information, so that students can gradually form good study habits and methods.
Emotions, attitudes and values
1. Through the observation of colorful chemical phenomena, students' curiosity and thirst for knowledge are stimulated and their interest in learning chemistry is cultivated.
2. Cultivate students' sense of cooperation and the scientific spirit of being diligent in thinking, brave in innovation and practice, and rigorous and realistic.
3. Understand the close relationship between chemistry and daily life and production, and improve students' ability to solve practical problems.
4. Easily master the knowledge of chemistry in interesting experiments and under the guidance of teachers, and experience the joy of learning.
Emphasis and difficulty in teaching
focus
Explore the chemical properties of common metals.
difficulty
Apply the chemical properties of metals initially and master new chemical reactions and reaction types.
teaching tool
Multimedia courseware; Experimental instruments: magnesium strip, aluminum sheet, copper sheet, iron sheet, alcohol lamp, crucible pliers, matches, sandpaper, dilute HCl, dilute H2SO4, test tubes (several).
teaching process
I. Review of knowledge
Phenomena and chemical equations of iron, magnesium and other metals burning in oxygen.
Second, the introduction of new courses.
Teacher: Compared with iron, what are the excellent properties of aluminum? Why are beverage cans usually made of aluminum instead of iron?
At present, some people can use brass as gold to cheat in some gold markets. Why do some people fall for it? What methods can be used for identification?
Raw armor: Brass and gold have different densities. You can distinguish them by measuring their density.
Health B: Brass and gold have different hardness. Describe them to each other. The hardness is brass and the hardness is gold.
Shengc:？ Real gold is not afraid of fire? . With fire, brass turns black and gold remains unchanged.
?
Teacher: Two methods, A and B, use the physical properties of metals, while method C uses the chemical properties of metals.
Teacher: If you want to use metals better, you need to know all kinds of properties of metals. In the last topic, we studied and studied the physical properties of metals. In this class, we will learn the chemical properties of metals.
[Blackboard] Topic 2 Chemical Properties of Metals
Third, the new curriculum teaching
Chemical properties of metals
[blackboard writing] 1. The reaction between metal and oxygen
The courseware shows gold necklaces, silver rings, students' knives, magnesium bars and other metal objects. Students observe the surface color.
Health: It's air!
Teacher: oxygen in the air, to be exact.
Experimental query 1
Step: 1. Use sandpaper to polish magnesium strip, aluminum sheet and copper sheet, then put them in the air, and observe and record the phenomenon after a period of time.
2. Clamp magnesium strip, aluminum sheet and copper sheet with crucible pliers, heat them on alcohol lamp, and observe and record the phenomenon.
Phenomenon: 1. The surface of magnesium strip and aluminum sheet darkens, while copper remains unchanged.
2. Magnesium rods burn violently in the air; The surface of aluminum plate loses luster; The surface of copper sheet turns black.
Conclusion: Metal can react with oxygen.
[Student Activity] Ask three students to write down on the blackboard:
2 mg +22 mg
4Al+3O22Al2O3
2Cu+O22CuO
Teacher: Can iron react when it is ignited in pure oxygen? If possible, write the chemical equation of the reaction.
[blackboard writing] 3Fe+2O2Fe3O4
Teacher: According to the above reaction, what kind of chemical properties can we get from metals?
Health: Metals can react with oxygen.
[Discussion] Most metals can react with oxygen, but is the difficulty and intensity of the reaction the same?
Health: magnesium, aluminum, etc. Can react with oxygen at room temperature; Iron and copper hardly react with oxygen at room temperature, but can react with oxygen at high temperature; ? Real gold is not afraid of fire? It shows that gold does not react with oxygen even at high temperature.
[Explanation] The nature of the reaction between metal and oxygen can be used to identify substances (such as brass and gold), and there are other uses. For example, aluminum has good corrosion resistance, because aluminum reacts with oxygen in the air to form a dense alumina film on its surface, thus preventing further oxidation of aluminum. The output of aluminum has been greatly improved in a short period of more than 100 years and has been widely used. In addition to improving the smelting method of aluminum, its cost is greatly reduced, and the density of aluminum is low. Another important reason is that aluminum has good corrosion resistance.
Teacher: The chemistry of aluminum is very active. Why are aluminum products usually resistant to corrosion? Why not use steel brush and sand to scrub aluminum products?
Health: the corrosion resistance of aluminum products is because aluminum can react with oxygen in the air and form a dense alumina protective film on its surface; If the aluminum products are scrubbed with steel brush and sand, it is easy to remove the aluminum oxide film, which does not play a protective role.
Teacher: What do we usually say? Anodized alumina? In fact, aluminum products use a special method to form a thick aluminum oxide protective layer on the aluminum surface.
[Blackboard] Two. Reaction of metals with acids
There is a phenomenon in life: mung beans will turn black when cooked in an iron pot; After apples and pears are cut with iron knives, their surfaces will also turn black. Excuse me, why is this?
Data: The cells of mung beans, apples and pears contain a substance called tannic acid, which can react with iron to produce black iron tannic acid.
Experimental inquiry 2 explores whether metals can react with acids.
(Divide the students into two groups: Group A and Group B)
Experimental steps:
Group A: Put appropriate polished magnesium strips, zinc particles, iron sheets and copper sheets into four test tubes respectively. Add about 5 mL of dilute hydrochloric acid and observe the phenomenon. Compare the severity of the reaction; Put a burning piece of wood at the mouth of the test tube, and observe and record this phenomenon.
Group B: The reaction phenomena were compared by replacing dilute hydrochloric acid with dilute sulfuric acid.
[experimental record]
Group a: courseware presentation
Group b: courseware presentation
[Conclusion] 1. Many metals can react not only with oxygen, but also with hydrochloric acid or dilute sulfuric acid.
2. Not all metals can react with hydrochloric acid or dilute sulfuric acid. Metals such as magnesium, iron and zinc can react with dilute sulfuric acid and dilute hydrochloric acid, while metals such as copper cannot react with dilute sulfuric acid and dilute hydrochloric acid.
3. The generated gas can be burned, which is proved to be hydrogen.
4. Different kinds of metals have different reaction intensities. Magnesium, zinc and iron react with hydrochloric acid or sulfuric acid to varying degrees, among which magnesium reacts most violently, followed by zinc and finally iron.
5. When reacting with acid, the metal that can produce hydrogen has strong activity, and vice versa. The severity of the reaction can also reflect the activity of the metal.
Third, displacement reaction.
[Question] Please analyze the similarity of the above four reactions from the categories of reactants and products, such as simple substances and compounds, and whether they are the same as the combination reactions and decomposition reactions we have learned.
Health: These reactions are characterized by the reaction of a simple substance with a compound to produce another simple substance and another compound. Its characteristics are different from those of combination reaction and decomposition reaction.
[Blackboard Book] Definition: The reaction between one simple substance and one compound to form another simple substance and another compound is called displacement reaction.
Features: a+BC = = = AC+B.
Summary after class
Fourth, class summary.
In this lesson, we learned two aspects of the chemical properties of metals: one is the reaction with oxygen, the other is the reaction with acid, and we also learned the displacement reaction. In the process of experimental inquiry, we should learn to analyze and summarize problems by comparative methods, find out the rules and deepen our understanding and mastery of knowledge. And gradually understand the differences of chemical properties of different metals.
Teaching objectives of teaching design of metal chemical properties
1. Understand that some metals are similar in chemical properties, but the difficulty and severity of the reaction are different.
2. Understand the characteristics of displacement response and judge it.
3. Memorize the activity sequence table of common metals.
4. Using metal activity sequence table skillfully to judge whether metals can be substituted in some solutions.
Emphasis and difficulty in teaching
The sequence of metal activities.
Preliminary study on metal activity sequence and judging displacement reaction by metal activity sequence.
teaching tool
Teacher: Tools for students to make multimedia courseware: magnesium bars, aluminum sheets, copper sheets, alcohol lamps, crucible tongs, matches, sandpaper, dilute HCl, dilute H2SO4, silver nitrate solution, copper sulfate solution, aluminum sulfate solution, aluminum wires, copper wires, magnesium bars, zinc particles, copper sheets, nails, sandpaper, matches and test tubes (several).
teaching process
[Introduction] In order to make better use of metals, it is necessary to understand the various properties of metals. Last class, we studied the physical properties of metals. In this class, we will learn the chemical properties of metals.
[Q] What color are the magnesium strips, aluminum sheets and copper sheets on the desktop?
Q: What happens when these metals are heated separately in air? Let's do this experiment.
Please write the chemical equation of the above reaction.
Ask a classmate to write on the blackboard.
[blackboard writing] 1. The reaction between metal and oxygen
Q: Can iron react when it is ignited in pure oxygen? If possible, write the chemical equation of the reaction.
[Q] According to the above reaction, what kind of chemical properties can we obtain from metals?
[Summary] Metals react with oxygen to generate corresponding metal oxides.
[blackboard writing] metal+oxygen? metallic oxide
Q: Is the reaction between metal and oxygen so violent? What is the difference?
Q: Can all metals react with oxygen? If not, can you give an example?
[q]? Real gold is not afraid of fire? What does this mean?
[Explanation] Experiments show that most metals can react with oxygen, but the difficulty and severity of the reaction are different. For example, magnesium and aluminum can react with oxygen at room temperature, while iron and copper hardly react with oxygen at room temperature, but can react with oxygen at high temperature. ? Real gold is not afraid of fire? It shows that gold does not react with oxygen even at high temperature. According to the above facts, we can judge the activity of these metals.
[Projection] Compare the activity of these metals just mentioned.
[Q] The chemical properties of aluminum are very active. Why are aluminum products usually resistant to corrosion?
[Explanation] The corrosion resistance of aluminum products is because aluminum can form a dense alumina film on its surface with oxygen in the air, thus preventing further oxidation of aluminum. The output of aluminum has been greatly improved in a short period of more than 100 years and has been widely used. In addition to improving the smelting method of aluminum, its cost is greatly reduced, and the density of aluminum is low. Another important reason is that aluminum has good corrosion resistance.
[Q] Why not use a steel brush and sandpaper to scrub aluminum products?
[Supplement] What do we usually say? Anodized alumina? In fact, aluminum products use a special method to form a thick aluminum oxide protective layer on the aluminum surface.
[Transition] Many metals can react not only with oxygen but also with hydrochloric acid or dilute sulfuric acid. Whether the metal can react with hydrochloric acid or dilute sulfuric acid and the severity of the reaction. Next, we will compare the reactions of magnesium, zinc, iron and copper with dilute acids through experiments.
Second, the reaction of metals with hydrochloric acid and dilute sulfuric acid.
[Design activities and exploration contents]
Put two small pieces of magnesium into a test tube, add 5mL of dilute hydrochloric acid, put the small piece of burning wood into the test tube, observe the phenomenon, and judge what gas is formed after the reaction.
Referring to the above experimental steps, dilute hydrochloric acid was added to the test tube containing two small pieces of zinc, iron and copper, respectively, and the phenomenon was observed and the severity of the reaction was compared. If gas is produced, judge what gas is produced.
Using dilute sulfuric acid instead of dilute hydrochloric acid to carry out experiments and compare the phenomena.
[Arrangement] The first group and the third group react the metal with dilute hydrochloric acid, and the second group and the fourth group react the metal with dilute sulfuric acid.
Ask a classmate to write the chemical equation of the reaction on the blackboard. This phenomenon can be dictated by students.
[Q] What conclusion did you draw from the above experiment?
[Evaluation] Everyone answered very well.
[Introduction] Appreciate the comparison of reactions between metals and hydrochloric acid in textbooks.
[Summary] Metals react with acids to produce metal compounds and hydrogen.
[blackboard writing] metal+acid? Metal compound+hydrogen
[Projection] Compare the activity of these metals used in the experiment just now.
[Transition] Let's observe these chemical equations.
[Projection] Mg+2HCl==MgCl2+H2?
Zinc+sulfuric acid = = zinc sulfate +H2?
Iron+sulfuric acid = = ferrous sulfate +H2?
[Q] What are the characteristics of these reactions in terms of the types of reactants and products, such as simple substances and compounds? Is it the same as the combination reaction and decomposition reaction we have learned?
[t] that's a good answer. Chemically, we call a reaction with this characteristic a displacement reaction.
displacement reaction
[Explanation] The reaction between a simple substance and a compound to produce another simple substance and another compound is called displacement reaction.
[Transition] Do we have any other methods to prove the relative strength of the activity of different metals?
[Q] Remember the reaction between nails and copper sulfate solution? Can you write the chemical equation of the reaction?
[Explanation] Iron is more active than copper, so iron can replace copper from copper sulfate solution.
[Projection] Metals with strong mobility can replace metals with weak mobility from their compounds.
[Transition] Next, we will explore the activity sequence of aluminum, copper and silver through this conclusion.
[Projection shows the contents of activities and explorations]
1. Immerse an aluminum wire polished with sandpaper in copper sulfate solution, take it out later and observe it. What will happen?
2. Immerse a clean copper wire in silver nitrate solution, take it out later and observe. What will happen?
3. Dip another clean copper wire into aluminum sulfate solution and take it out later for observation. What will happen?
What conclusions can you draw from these experiments? Can the metal activity order of aluminum, copper and silver be obtained from this?
[Summary] Metals react with metal compound solutions to generate new metal compounds and new metals.
[blackboard writing] metal+metal compound? New metal compound+new metal
[Projection] Compare the activities of these three metals used in the experiment just now.
[Explanation] After many times of inquiry similar to the above experiments, people have seriously removed the false from the true. Based on the analysis from the surface to the inside, the activity sequence of common metals in solution is summarized:
[blackboard writing] 3. Sequence of metal activity
[Projection and Interpretation] The sequence of metal activities has important applications in industrial and agricultural production and scientific research, which can give you the following judgment basis:
1. In the sequence of metal activity, the higher the position of a metal, the stronger its activity.
2. In the metal active sequence, the metal before hydrogen can replace hydrogen in hydrochloric acid and dilute sulfuric acid.
3. In the sequence of metal activities, the former metals can displace the latter metals from the solution of their compounds.
[Projection exercise] Can the following substances react? Write the chemical equation that can react and judge whether it is a displacement reaction.
(1) silver and dilute hydrochloric acid (2) zinc sulfate and copper sulfate solution
(3) copper sulfate and zinc sulfate solution
(4) aluminum nitrate and silver nitrate solution
Question 1: Bordeaux mixture is a common fungicide in agriculture. It is made of copper sulfate and lime with water. Why can't we use iron containers to prepare Bordeaux mixture?
Question 2: The fake in gold ornaments is often a fake, and some lawless elements in society often pass off brass as gold for fraud. Brass (copper-zinc alloy) looks like gold. How do we identify them?
[Summary] Through the study of this topic, we know that most metals can react with oxygen, and different metals have different activities. According to the reaction of metal with acid or metal with another metal compound, the relative strength of metal activity can be judged. We also know the sequence of activities of several common metals. At the same time, we also know a new type of reaction-displacement reaction.