教学目的: 1.初步了解物质的组成,认识分子的真实存在;掌握分子的概念。 2.用分子的观点区别物质的两种变化;会区别纯净物和混和物。 3.学会用分子的观点解释物质溶解、蒸发、热胀冷缩、三态变化等现象。 引入新课提问: ①湿衣服晾晒后为什么会干? ②在房子里洒些香水为什么整个房子都有香味? ③铁轨的接头处为什么要留一定的间距? Teaching Objectives: 1 preliminary understanding of the composition of matter, understanding of the real existence of molecules; master the concept of molecules. 2. Differentiate two types of material changes from a molecular point of view; distinguish between pure materials and mixtures. 3. Learn to use the molecular point of view to explain the material dissolved, evaporated, thermal expansion and contraction, three-state changes and so on. Introducing a new lesson Question: ①When the wet clothes dry, why do you dry? ② Sprinkle some perfume in the house, why the whole house has a fragrance? ③ rail joints why stay at a certain distance?