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化合价是元素的一种重要性质,它有其自身的一些规律性.在解答某些化学题时.如果能巧妙地应用化合价的规律,会收到意想不到的效果.现将化合价在中学化学解题中的应用方面归纳如下:一、判断和书写物质的分子式元素化合价是判断和书写化合物分子式的一个重要依据,基本原则是:化合物里各元素正负化合价的代数和为零.这一原则是书写化合物分子式、计算化合物中元素的化合价和判断物质分子式是否正确的依据.书写化合物的分子式时,一般将正价元素写在右边,负价元素写在左边.但要注意,第ⅣA和第ⅤA旅元素的氢化物分子式的书写则正好相反.这亦是根据物质分子式分析、计算元素化合价的依据.现举例如下:
Valence is an important property of the element. It has its own regularities. When answering certain chemistry questions, if one can skillfully apply the law of valence, it will receive unexpected results. Now chemical analysis of valence in middle school The application aspects of the questions are summarised as follows: I. Judging and writing The molecular elemental valences of substances are an important basis for judging and writing the molecular formulae. The basic principle is: the algebraic sum of the valences of the elements in the compound is zero. This principle is The formula for writing compound formulas, calculating the valences of elements in compounds, and determining the correctness of the molecular formulas for the compounds. When writing formulas for compounds, the positive and negative elements are usually written on the right, and the negative elements are written on the left. Note, however, that IVA and VA The hydride formula of the brigade element is written in exactly the opposite way. This is also based on the analysis of the molecular formula and the basis for calculating the elemental valence. The following examples are given below: