Academic journal article Journal of College Science Teaching

A Hands-On Activity to Build Mastery of Intermolecular Forces and Its Impacts on Student Learning

Academic journal article Journal of College Science Teaching

A Hands-On Activity to Build Mastery of Intermolecular Forces and Its Impacts on Student Learning

Article excerpt

Science students struggle to unite course content with real-world experiences and, generally speaking, the more abstract the subject matter, the more difficult it is for learners to make this connection (Bodner, 1986; Herron, 1975; Johnstone, 1991, 1993). Intermolecular forces, which directly impact the physical properties of all substances, are a challenging subject because they are abstract in nature (Henderleiter, Smart, Anderson, & Elian, 2001; Jaisen, 2008; Wedvick, McManaman, Anderson, & Carroll, 1998). However, because intermolecular forces have direct applicability to real-world observations and phenomena, mastery of this subject is crucial. Although intermolecular forces are typically associated with chemistry courses, their significance is not limited solely to chemistry, as general biology and molecular biology also use intermolecular forces as a rationale to explain phenomena (Leckband & Israelachvili, 2001).

Intermolecular forces are used as a means to explain solubility, boiling point, viscosity, surface tension, micelle formation, and nonideal gas behavior in general chemistry, organic chemistry, biochemistry, and physical chemistry. In addition, intermolecular forces are the theoretical basis for distillation, a ubiquitous laboratory technique used in myriad science courses. Although students may understand and observe experimentally that the boiling points of ethanol and 1-hexanol differ, it would be impossible to explain the reason for this difference without the use of intermolecular forces. Additionally, intermolecular forces are an important concept for students of biochemistry, general biology, and molecular biology, as they are a driving factor behind protein secondary and tertiary structures. For instance, in biochemistry and molecular biology, instructors explain hydrogen bonding and hydrophilic/hydrophobic interactions of amino acid R-groups as a major contributor to protein shape and functionality. Additionally, hydrogen bonding is used to explain the stabilization of the DNA double helix.

Unfortunately, the abstract nature of intermolecular forces is a stumbling block for students (Henderleiter et al., 2001; Jaisen, 2008; Wedvick et al., 1998), and a lack of mastery of molecular structures can be counted among the reasons for the difficulties students face with intermolecular forces (Cooper, Grove, Underwood, & Klymkowsky, 2010; Cooper, Underwood, Hilley, & Klymkowsky, 2012; Henderleiter et al., 2001; Jaisen, 2008; Wedvick et al., 1998). Additionally, when van der Waals forces are conceptually introduced and then derived mathematically to explain nonideal gas behavior, learners of chemistry tend to struggle to connect mathematics to physical phenomena (Nakhleh, Lowrey, & Mitchell, 1996; Nakhleh & Mitchell, 1993).

The literature contains many laboratory experiments, computer simulations, and demonstrations to illustrate intermolecular forces and their effects on physical properties (Bruist, 1998; Casey & Pittman, 2005; Earles, 1995; Hoffman, 1982; Holt, Grabow, & Pursell, 2003; Kimbrough & DeLorenzo, 1998; Montes, Lai, & Sanabria, 2003; Mundell, 2007, 2009; Schultz, 2005; Silverstein, 1998a, 1998b), and others have described bonding and intermolecular forces (Burkholder, Purser, & Cole, 2008; Jaisen, 2008). However, no assistance or guidance is available to educators regarding how to build and develop students' mental models of intermolecular forces. The activity presented in this article fills this hole by engaging students in building their ideas about intermolecular forces though pedagogically sound methods.

Activity design

Students who struggle to grasp abstract concepts benefit from their use of physical manipulatives and relatable objects to solve problems, as learners at this level are unable to visualize such ideas on their own without assistance (Bloom, 1956). To address the challenges that students face with regard to intermolecular forces, a hands-on activity was developed to assist learners in identifying and applying intermolecular forces. …

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