HSAB Rules - HSAB Rules

Japanese: HSAB 則 - えっちえすえーびーそく

…Hard acids and bases, and soft acids and bases, tend to form stable chemical species, while hard bases and soft acids, and vice versa, tend not to form stable chemical species. In 1963, R.G. Pearson expanded these relationships further and organized them into a systematic rule, which he named the HSAB rule, short for hard and soft acids and bases. The classification of elements or coordinate atoms according to the HSAB rule is based on an essential understanding of chemical bonds, and the skillful application of this rule makes it possible to provide a unified explanation and interpretation of a wide range of topics, including the stability of compounds, the solubility of sparingly soluble salts, reaction rates, and equilibrium positions, as well as the occurrence of elements, the formation of mineral deposits, and the distribution and transmigration of elements. …

From [Acids and Bases]

...This also means that bonds between hard substances are strongly ionic, while bonds between soft substances are strongly covalent. This is generally called the HSAB principle (hard and soft acids and bases). [Nakahara Katsumasa]...

*Some of the terminology used in reference to the "HSAB Rules" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…硬い酸･塩基どうし，軟らかい酸･塩基どうしは安定な化学種をつくりやすく，硬い塩基と軟らかい酸およびその逆の組合せでは安定な化学種をつくりにくい。1963年ピアソンR.G.Pearsonはこのような関係をさらに拡張して系統的規則にまとめ，hard and soft acids and basesを略してHSAB則と名づけた。HSAB則による元素または配位原子の分類は，化学結合の本質的な把握をその根底に置くもので，この規則を巧みに適用すると，化合物の安定性，難溶塩の溶解度，反応速度，平衡位置をはじめ，元素の産状，鉱床の形成，元素の分配や輪廻（りんね）などに関し，広範囲に及ぶ統一的な説明･解釈が可能になる。…