A Experimental Study Of Promoting The Middle School Students To Develop Views Of Chemical Elements

Helping students develop fundamental chemical conceptions is one of the important teaching aims in chemistry subject.The views of chemical elements is the core chemical conception.In this paper the basic questions studied are:(1)explore the basic contents of the views of chemical elements in junior stage.(2)Study the basic forming pocess and the influencing factors of the views of chemical elements.(3)Investigate the current condition of the students constructing the views of chemical elements.(4)With the direction of theory and practice,put forward the basic strategies of the students constructing the views of chemical elements and conduct the expremental study.the basic contents of the views of chemical elements in junior stage are:(1) element is the general term for the same type of atoms,which have the same nuclear charge number(ie, the number of protons).(2)valence of the element is relative to the outermost electron of the atom.(3)matter is composed of elements.(4)matter may be categorized according to the composing elements.(5)the chemical formula indacates the composing elements of the matter.(6)matter which has the similar composing elements has the similar nature.(7)chemical reaction may be classified according to the combining ralation of the elements. There are six stages: (1)choosing, acquiring and accumulating the matter-related knowledge.(2)structuring the matter-related knowledge and initially constructing views of matter. (3) choosing,acquiring and accumulating the element-related knowledge.(4)structuring the element-related core concepts.(5)problem-forming and problem-solving.(6) initially developing views of chemical elements.The survey indicated that junior students had the questions below in constructing the views of chemical elements.(1)the junior students'study just stagnated on the level of remembering the factual knowledge.(2) the junior students didn't develop the elementary cognition.(3) the junior students couldn't understand the basic types of chemical reaction from the point of re-combination of the atoms.(4) the junior students didn't construct the conception that the properties of matter is relative to the composition of elements.The experimental study indicates that the strategies of constructing the views of chemical elements below is effective. (1) On the base of learning the familiar matter around,recognize that the outstanding property of elements is that its conbinableness is strong. (2) Know matter from the point of element and comprehend the element characteristic of matter.(3)understand the classfication of matter from the point of element and rocognize that matter which has the similar composing elements has the similar property. (4)On the base of atomic stucture,comprehend how elements combine into matter.(5)know the change of matter from the point of element and form the cognition of elemental conservation while matter transforming.(6)construct gradually the views of chemical elements by combining specialized study and unit study.(7)use concept-map technology to help construct the views of chemical elements.