Ion Valence - Ion Ka

The amount of electricity an ion possesses divided by the elementary charge. It is also called the charge or valence of an ion. Sometimes it refers only to the absolute value. For elements, it is related to their position in the periodic table; for typical elements that tend to stabilize by adopting a rare gas-type electron arrangement, Group 1 alkali metals lose one electron in their outermost shell and become +1 valence, and Group 17 halogen elements gain one electron in their outermost shell and become -1 valence. There is no consistent trend for transition metal element cations, which have stable structures different from the rare gas type.

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

イオンのもつ電気量を電気素量で割った値．イオンの電価，イオンの価数ともいう．絶対値だけをいうこともある．元素については，希ガス型電子配列をとって安定化する傾向のある典型元素では，1族アルカリ金属では最外殻電子1個を失って＋1価，17族ハロゲン元素では最外殻に電子1個を収容して－1価をとるように，周期表の位置と関係がある．希ガス型とは異なる安定構造をもつ遷移金属元素陽イオンでは，一定した傾向はない．

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