初中化学中，氢、氧、铁、碳、酸、碱、盐、氧化物等元素及其化合物知识是中考化学的重点内容，90％以上的中考考点涉及元素及其化合物知识。不仅如此，它也是初中化学最基础最重要的内容，离开元素及其化合物，就无所谓实验可言，基本概念和基本理论就会无血无肉，化学基本计 In junior chemistry, the knowledge of hydrogen, oxygen, iron, carbon, acid, alkali, salt, oxides, and other elements and their compounds is the key content of the chemistry of middle entrance exams, and more than 90% of the examinations involve the knowledge of elements and their compounds. Not only that, but it is also the most important content of junior high school chemistry. If you leave the elements and their compounds, it doesn’t matter what the experiment is. The basic concepts and basic theories will be bloodless and the basic chemistry