在讲完门捷列夫周期律和周期表(初步认识)以後,依照周期表的系统开始讲非金属元素的各族,在这些族里苜先研究卤族元素和它们的重要化合物。当研究元素及其化合物时必须注意使学生了解以下各问题: 1)物质在自然界的存在; 2)制法(实验室制法和工业制法); 3)物理性质(物态、颜色、气味、溶解度等); After reading Mendeleev’s periodic law and periodic table (preliminary understanding), the system according to the periodic table began to speak of the non-metallic elements of the raccoon family in which they first studied the halogen elements and their important compounds. When studying elements and their compounds, care must be taken to familiarize the students with: 1) the existence of the substance in nature; 2) the system of manufacture , Solubility, etc.);