对化学键理解的两个层级:以超价分子的化学键模型为例

Two Levels of Understanding of Chemical Bonds:a Case of the Bonding Model of Hypervalent Molecules

化学键是整个化学领域的核心概念之一,但必须清楚的是,化学键是人为抽象出来的概念,而不是物理现实。为正确描述化学键,历史上各种化学键模型或者理论被提出,其中基于经验规则的电子对成键模型和杂化轨道理论目前最广为接受。然而,经验规则毕竟有其适用范围,譬如对于超价分子的解释就存在不合理之处。我们建议在教学中以超价分子为例,对低年级学生明确指出经验规则在化学成键描述中的不足,高年级时运用分子轨道理论或现代价键理论开展成键分析的专题讨论。期望学生在掌握化学键概念的同时,对分子成键行为的见解持开放态度,培养其科学求知的精神。

Chemical bonding is one of the core concepts in the whole field of chemistry and provides a very effective way of communication.It must be clear that chemical bonds are not real,they are artificially abstracted concepts.To accurately describe chemical bonding,various models or theories have been proposed throughout history.The most widely used models are the electron-pair bonding model and hybrid orbital theory.However,the rules of thumb have their limitations,as evident in the explanation of hypervalent molecules.We suggest that in teaching,hypervalent molecules should be used as examples to explicitly point out the shortcomings of empirical rules in describing chemical bonding to younger students.In another hand,molecular orbital theory or modern valence bond theory can be used on bonding analysis for senior students.It is expected that students maintain an open-minded attitude towards the behavior of chemical bonding and cultivate spirit of scientific inquiry.