"Classification and transformation of substances" is the content of the first section of the first chapter of the compulsory chemistry course of PEP/KLOC-0, and it is an important carrier to complete the connection of junior high school and senior high school. It expands the single and isolated substance and reaction learned in junior high school into a diverse and systematic substance reaction system in senior high school, permeates the basic thinking methods of chemistry learning such as classification view and substance transformation view, and aims to discover the law of substance and its change, and predict the substance accordingly. This part belongs to the second theme of Chemistry Curriculum Standard for Senior High School (20xx Edition): Common inorganic compounds and their applications, which requires that "elements can form different kinds of substances, and substances can be classified according to their composition and properties; Similar substances have similar properties, and under certain conditions, various substances can be transformed into each other; Understand that colloid is a common dispersion system. " Firstly, the methods of material classification are introduced in detail to understand the material world from the perspective of various classifications; According to the diameter of dispersoid particles, the basic concept of colloid is introduced to supplement the understanding of mixture system in junior high school, and then representative substances are selected to explore the transformation law of "simple substance-basic oxide-alkali-salt" and "simple substance-acidic oxide-acid-salt" representing metal or nonmetal elements respectively, and to guide production and life practice. Through the study of the content of this lesson, students not only need to reasonably relate the knowledge learned in junior high school from point to line, but also need to start to construct and gradually form basic chemical concepts on the basis of their factual knowledge, so as to guide the follow-up content learning in senior high school and realize the improvement of subject literacy.
Second, the analysis of learning situation
Through the study in junior high school, students have mastered the basic properties of some typical substances, involving simple substances, oxides (metal oxides and non-metal oxides), acids, bases, salts and other substances. However, students' knowledge is single and scattered, and there is no systematic integration, so they can't understand the laws contained in it more clearly. In senior high school, students will no longer face a single material, but often a complex, practical and even unfamiliar material system, which urgently needs the guidance of disciplinary thinking methods. From this, we can analyze the development points of students as follows:
1. Based on the idea of classification, build and enrich the framework of chemical knowledge in the follow-up study, and form the basic mode of chemical learning.
2. Understand the basic law of material transformation, push the thinking mode of junior high school memory to the thinking mode of senior high school reasoning, and improve learning interest.
3. Learn to transfer the learning strategies in this section to the acquisition of other thinking methods in chemistry. In the face of complex and unfamiliar chemical problems, you can be justified.
Third, the teaching objectives
1. Based on the concept of classification, according to the composition of elements, known substances can be simply classified according to different classification standards, and the relationship between elements and substances can be established by tree classification and cross classification.
2. Learn to classify the mixture from the perspective of particle size, understand the basic concepts such as dispersion system and colloid, and master the important properties of colloid.
3. Explore the law of substance transformation based on substance category, and master the relationship and transformation characteristics among simple substance, oxide, acid, alkali and salt.
4, can apply the concept of classification and the law of material transformation to solve practical problems.
Fourth, the focus of teaching
1. Establish a classification view and systematically integrate the existing knowledge.
2. Accurately understand the concept of colloid and master its importance.
3. Understand the law of material transformation and use it to solve simple problems.
Difficulties in teaching verbs (abbreviation of verb)
1. Establish a classification view and use it to explore the law of material transformation.
2. Apply the law of material transformation to solve practical problems.
Sixth, the teaching process.
(1) link 1
1, introduces the classification with examples, and clarifies its application value.
Instructor's guidance: Introduce the examples of displaying different kinds of articles in the library or supermarket, clarify the importance of classification in practical application, and list the classification methods such as "cross classification" and "tree classification".
Student activities: feel the advantages of classification. It is necessary to summarize the characteristics of substances and determine the classification standards. Different standards will lead to different classification results.
Design intention: Students are familiar with the examples of classification in life, have a sense of substitution and are interested, and at the same time can strengthen the important application of classification. At the same time, it is clear that the classification needs standards, and it is necessary to find * * * as the theoretical basis for subsequent analysis of the homogeneity of a class of substances.
2, practical activities, the application of classification to classify substances.
Teacher's instruction: Task 1 Classify "substances", clarify the * * * properties (definitions) of various substances, and give examples.
Student Activities: Classify the substances as follows:
Design intention: to systematically classify the single substance learned in junior high school, so as to pave the way for the subsequent search for the * * * nature of similar substances.
(2) Link 2
1, introducing the concepts of dispersion system and colloid.
Teacher guidance:
Can the problem mixture be subdivided? Review the concepts of solution and suspension, summarize the characteristics of * *, and get the concept of dispersion system. The dispersion system is classified according to the state of dispersoid and dispersant, and an example is given. According to the size classification of dispersoid particles, the concept of colloid is introduced and an example is given.
Student activities:
(1) Review solutions and suspensions, and summarize the concept of dispersion system.
(2) The dispersion system is classified and the definition of colloid is deduced, that is, the diameter of dispersoid particles is 1- 100nm.
Design intention: review the knowledge learned, cultivate students' summing-up ability, reclassify the mixture and make up for the vacancy in material classification.
2. Explore the properties of colloid by experiments.
Teacher's instruction: In the demonstration experiment, the copper sulfate solution and the newly synthesized iron hydroxide colloid were irradiated with a laser pen, and the experimental phenomena were observed to obtain the colloid properties, and the Dindar phenomenon in life was listed.
Students' activities: Observe the experimental phenomenon, get the colloidal property-Tindal effect, and think about and understand the causes of Tindal effect.
Design intention: to guide students to explore colloid properties from macro phenomena and micro essence, and draw conclusions through observation and analysis.
3. Identification, separation and purification of colloid.
Teacher's guidance: Task 2 identifies sodium chloride solution and starch colloid according to their properties, and designs experiments to separate their mixture.
Student activities: According to the different particle sizes of dispersoid, students use semi-permeable membrane to design the experiment of separating colloid and solution to test whether the separation is successful.
Design intention: Diagnose and evaluate students' mastery of the nature and properties of colloid, train students' experimental ability and deepen their understanding of colloid.
(3) Link 3
1. Explore the transformation law between simple substance-oxide-acid (alkali)-salt.
Teacher's guidance: Task 3 classifies the representative substances learned in junior high school, taking Ca, CaO, Ca(OH)2 and CaCO3 as examples, and explores the transformation law among simple metal, alkaline oxide, alkali and salt; Taking carbon, carbon dioxide, bicarbonate and calcium carbonate as examples, the transformation law among nonmetallic elements, acid oxides, acids and salts is discussed.
Student activity: Combining with specific examples, summarize the transformation law between simple substance-oxide-acid (alkali)-salt, and complete the writing of reaction equation.
Design intention: summarize and integrate the knowledge learned in junior high school, and look for the transformation law between substances on the basis of classification.
2. According to the known situation, summarize the commonness of acid, alkali and salt.
Teacher's guidance: Task 4 summarizes the commonness of acid, alkali and salt with examples.
Student activities: think and discuss, sum up the commonness of acid, alkali and salt,
Universality of (1) acid: make indicator change color;
React with active metal to generate salt and hydrogen;
React with alkaline oxide to generate salt and water;
React with alkali to generate salt and water;
React with salt to form new salt and new acid.
(2) universality of alkali: make indicator change color.
React with acid oxide to generate salt and water;
React with acid to form salt and water;
React with salt to form new alkali and new salt.
(3) universality of salt: react with metal to generate new metal and new salt (metal activity law);
React with acid to generate new salt and new acid;
React with alkali to generate new salt and alkali;
React with salt to form two new salts (according to the law of double decomposition reaction).
Design intention: Summarizing the reaction law of acid, alkali and salt, reflecting the category of substance, is an important basis for exploring the transformation of substance. Cultivate students' ability to sum up and improve.
3. Based on the above two points, the transformation relationship between substances is improved by using the "eight diagrams".
Teacher-student activities: * * * Complete the writing of "Eight Circle Diagram" together.
Design intention: "Eight Diagrams" is a concentrated expression of the law of material transformation, and it is also an important tool, which can be used to deeply understand the relationship between material categories and the transformation of various materials, and can also be used to design the path of material transformation.
(4) Link 4
Teacher's guidance: Task 5 is to design experiments to prepare sodium sulfite with sulfur as raw material according to the law of material transformation.
Student activities:
(1) Define the categories of raw materials and products.
(2) Design reaction paths according to the "eight-circle diagram" and encourage the design of multiple paths to complete the preparation.
(3) Write the reaction equations involved in the preparation process.
Design intention: Diagnose and evaluate students' mastery of the laws of substance classification and substance transformation, and experience the application value of the concepts of classification and transformation in solving practical problems.