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化学式的书写和意义是九年制义务教育化学教材的一个重要内容,掌握了化学式,不但可以巩固元素符号的书写,而且对学生判断物质的分类,掌握物质的宏观组成和微观结构具有决定性的作用,同时也为化学方程式的书写打下坚实的基础。化学式是用元素符号和数字的组合来表示物质组成的式子,是通过实验的方法测定物质组成后得出来的。由于混合物没有固定的组成,故混合物都没有化学式,而纯净物都可以通过实验测定出组
The writing and meaning of chemical formula is an important part of nine-year compulsory education chemistry textbook. Grasping the chemical formula can not only consolidate the writing of element symbols, but also play a decisive role in students’ judgment of the classification of materials and the mastery of the macroscopic composition and microstructure of matter , But also lay a solid foundation for the writing of chemical equations. Chemical formula is a combination of symbols and numbers to represent the material composition of the formula is determined by experimental methods of material composition derived. Since the mixture has no fixed composition, the mixture has no chemical formula and the pure substance can be determined experimentally