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人们对物质是从两个角度去认识的。一是宏观的角度;二是微观的角度。初中化学第一章第五节“原子”以及第二章第四—七节“核外电子排布”“离子化合物和共价化合物”等内容就是为了使学生对物质的组成有一个初步的微观认识。这里首先是原子如何形成分子。在这段教学中,主要讲清“化合价和作用力”即:原子化合价(?)作用力分子其中重点和难点是化合价的概念。学生为什么对“化合价”的概念难以理解和接受呢?大致有两点原因:1.化合价概念的抽象性和概括性强。这部分知识可以说没有简捷的实验能够帮助同学去直接感知。而且由于学生受化学知识的局限,
People understand matter from two angles. The first is the macro perspective; the second is the micro perspective. The fifth chapter of the junior high school chemistry “Atomic” and the second chapter of the fourth-seventh chapter “Extra-nuclear electronic arrangement” and “Ionic compounds and covalent compounds” are intended to give students a preliminary microscopic view of the composition of matter. understanding. Here is how atoms form molecules first. In this teaching, we mainly talk about “combined valence and force”, that is, the concept of valence. Why students are difficult to understand and accept the concept of “combined price”? There are roughly two reasons: 1. The concept of valence is very abstract and general. This part of the knowledge can be said that there is no simple experiment can help students to directly perceive. And because students are limited by chemical knowledge,