The nature of sodium teaching plan
First, the teaching objectives
1. can tell the main physical and chemical properties of sodium; Can describe the experimental phenomenon of sodium reacting with water, and can write the chemical equations of sodium reacting with water and sodium reacting with oxygen.
2. Learn how to explore the properties of materials through experimental exploration.
3. Cultivate cooperation consciousness and team spirit through group cooperation experiments; By studying the nature of sodium, we can establish a sense of security in life.
Second, the difficulties in teaching
Focus on the chemical properties of sodium and the reaction between sodium and water.
Analysis of difficulties in experimental phenomena.
Third, the teaching process
Link 1: Introducing a new lesson
The teacher performed a chemical magic trick: "before class, a small piece of sodium was hidden in the wick of the alcohol lamp." At the beginning of the experiment, drop a drop of water in the wick with a rubber dropper. Organize students to observe the experimental phenomena carefully.
Question: "Why did you light the alcohol lamp with water in the experiment just now?"
Introduce a new lesson: This is because there is metallic sodium in the wick. Today we will discuss the properties of sodium metal together.
Link 2: Explore new knowledge
Experimental exploration 1: physical properties of sodium.
Teacher: Show the metallic sodium stored in the reagent bottle, and emphasize the methods and precautions of taking sodium (take a small piece of sodium with tweezers, and dry the kerosene on the surface with filter paper; Put the sodium on the glass, cut a piece of mung bean with a small knife, and put the remaining sodium back into the original reagent bottle. )
Ask: "What experimental phenomena have been observed? What do you mean? "
Students observe, think, express phenomena and summarize properties: sodium is preserved in kerosene, silvery white metal, less dense than water and soft.
Experimental inquiry 2: the reaction between sodium and oxygen under heating conditions.
Experimental process: a small piece of sodium metal is heated on asbestos net.
Ask: "What experimental phenomena have been observed? What kind of conclusion is drawn? "
Students conduct experiments, observe, express phenomena and summarize the nature. (reactivity, melting point)
The teacher explained: Sodium and oxygen are heated to produce light yellow sodium peroxide. Sodium peroxide reacts with water to release a lot of heat and produce oxygen. When the temperature reaches the ignition point of cotton, cotton burns.
Students write the chemical reaction equations of sodium and oxygen at room temperature and heating conditions respectively.
The teacher emphasized the influence of chemical reaction conditions on chemical reaction.
Experimental Inquiry 3: The reaction between sodium and water.
The teacher demonstrated the experiment: drop a few drops of phenolphthalein solution into a beaker filled with water, and then add a small piece of metallic sodium the size of a soybean grain to observe the experimental phenomenon.
Ask the question: "What experimental phenomena have been observed and what conclusions have been drawn?"
Students conduct experiments, observe and express phenomena, and guide students to draw conclusions.
Teacher's explanation: the experimental phenomenon can be summarized as "floating, melting, swimming, ringing and red", and the corresponding conclusion is drawn (the density of sodium is less than that of water, the melting point of sodium is low, the reaction between sodium and water gives off heat, the reaction gives off gas, and the generated substance is alkaline).
Ask the question: "What is the gas produced? How to verify that the generated gas is hydrogen? "
Guide students to carry out theoretical analysis and design experimental schemes for verification experiments.
The teacher gave an improved experimental device and scheme.