化合价是初中化学的重要概念之一,它是书写物质的化学式、检查化学式是否正确的依据·近年来,有关化合价的计算频频出现于试题中,成为中考的必考考点,不少题目还有一定的难度·因此必须牢记化合价规律,并掌握相关的计算技巧.一、化合价的一般规律为便于记忆化合价规律,特编歌诀 Valence is one of the important concepts of junior high school chemistry. It is the basis for the correct chemical formula and chemical formula of the written substance. In recent years, the calculation of valence has frequently appeared in the test questions, and it has become a mandatory test point for the Chinese exam. The difficulty, so we must keep in mind the law of valence, and master the relevant calculation skills. First, the general law of valence to facilitate the memory of the law of compliance, special songs