noun
hypervalent compound
Chemistry term for a compound in which a central atom has more than eight electrons in its valence shell.
超原子価化合物は、中心原子がオクテット則を超える結合を持つ。
Hypervalent compounds have bonds where the central atom exceeds the octet rule.
Compound of 超 (chō, 'hyper-') + 原子価 (genshika, 'valence'). The term is a direct calque of English 'hypervalent'.