Authentic Assessment Tool for the Measurement of Students' Understanding of the Valence Shell Electron Pair Repulsion Theory

Karntarat Wuttisela

doi:10.13189/ujer.2017.050912

Abstract

There are various types of instructional media related to Valence Shell Electron Pair Repulsion (VSEPR) but there is a lack of diversity of resources devoted to assessment. This research presents an assessment and comparison of students' understanding of VSEPR theory before and after tuition involving the use of the foam molecule model (FMM) and hands-on activities in which students created models that represented 13 molecule shapes. It was found that the molecules that were created correctly before and after tuition were in the system without lone pair electrons (AX2) and the system with lone pair electrons (AX2E2). The molecules with which the students had most misconceptions, before and after tuition, were from the system without lone pair electrons (AX5) and the system with lone pair electrons (AX2E). These findings suggest that the FMM can be used as an assessment tool to reduce misconceptions about VSEPR theory.

Highlights

Understanding the molecular geometry of a compound may help to determine its physical and chemical properties such as the polarity, melting point, boiling point, and density
The systematic way to predict the geometry of molecules is divided into two categories, the central atom with and without lone pairs
A represents the central atom, X represents bond pairs or surrounding atoms, and n represents the number of bonds with the central atom

Summary

Introduction

Understanding the molecular geometry of a compound may help to determine its physical and chemical properties such as the polarity, melting point, boiling point, and density. The use of the foam molecule model (FMM) helps do this and does not add to the workloads of teachers This is a model without holes, so students must create the molecule shapes through systematic and reasonable thinking by consideration of the repulsion between lone pair and bonding pair electrons. This research provides an assessment tool for teachers to measure students’ understanding of VSEPR theory by the use of hands-on activities in the teaching and evaluation stages, and allows learning to occur by doing. Molecules models made of foam help to provide evaluation, and understanding can be measured according to the sizes of atoms, types of covalent bonds, bonds angles, and shapes of molecules. It encourages them to understand actual theory and to generate creative ideas

Materials and Methods

Methods

Results

Conclusions