Coordination polyhedron

Japanese: 配位多面体 - はいいためんたい（英語表記）coordination polyhedron

When considering the crystal structure of inorganic substances and minerals as a collection of hard-sphere atoms, cations are surrounded by a group of anions. The polyhedron formed by connecting the centers of these anions is called a coordination polyhedron, and the number of such polyhedrons is called the coordination number. If we assume that the distance between cations and anions is approximately equal and accept the empirical rule that "as long as all anions are in contact with a cation, the number of anions surrounding the cation will be as large as possible," then the coordination polyhedron can be estimated by the ratio of the radii of cation A and anion X, r _A / r _X.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

おもに無機物質，鉱物の結晶構造を剛体球の原子の集合とみなして考えたとき，陽イオンは一群の陰イオンによって取り囲まれている。この陰イオンの中心を結んでできる多面体を配位多面体と呼び，その数を配位数という。陽イオンと陰イオンの距離をほぼ等しいとし，〈すべての陰イオンが陽イオンに接している限り，陽イオンのまわりを取り囲む陰イオンの数はできるだけ大きくなる〉という経験則を受け入れると，配位多面体は陽イオンAと陰イオンXの半径の比r_A/r_Xにより推定できる。

出典　株式会社平凡社世界大百科事典第２版について　情報

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