广义的酸碱包括的物质种类极为广泛,绝大多数化合物皆可看作是酸碱的加合物。所有的化学反应,除氧化还原反应而外,皆属酸碱反应。因此,酸碱的软硬概念和“硬亲硬、软亲软”原理有广泛的联系。软硬酸碱原理的提出完全是经验的总结。后来有人应用前沿分子轨道微扰理论予以说明,从而使之具有理论的意义。但至今还没有一个定量标度可以把酸碱的软硬性和它们的反应性或其它性质联系起来。实际上,已有多人根据酸碱的若干基本性质,如电负性、电离 The wide range of acids and bases includes a wide range of substances, most of which can be regarded as acid-base adducts. All chemical reactions, in addition to oxidation and reduction reactions, are all acid-base reaction. Therefore, the acid-base concept of hard and soft and “hard-hard, soft-soft” principle has a broad link. Soft and hard acid-base principle is entirely an empirical summary. Later, some people use the theory of precursor molecular orbital perturbation to explain, so that it has theoretical significance. However, to date, there has not been a quantitative scale that links acid-base hardness to their reactivity or other properties. In fact, there are many people based on the acid-base of several basic properties, such as electronegativity, ionization