用电子云表示原子中电子的运动情况是个最常用的方法。它对于理解原子结构和原子间成键的原理有极重要的作用。因此,在无机化学、有机化学和物质结构等课程中都要讲授。但在目前的几本教科书中介绍得不很准确,甚至还有错误。因而造成学生学习的困难,或者是得到一个模糊的概念。这里想对它作个确切而简单的叙述。 Using the electron cloud to represent the movement of electrons in an atom is the most commonly used method. It plays an important role in understanding the principles of atomic structure and inter-atomic bonding. Therefore, teach in inorganic chemistry, organic chemistry and material structure courses. However, it is not very accurate or even wrong to introduce in several current textbooks. As a result, students find it difficult to learn or get a vague concept. Here I want to make a precise and simple account of it.