CTS Guide: Chemical Bonding, pp 150-151- Section IV Research Summaries

Bonding

  • Some students adopt anthropomorphic language to describe why atoms “want” to form bonds. An extension of the idea that atoms “need” to form bonds is that atoms “make decisions” about forming bonds. This may come from analogies used in teaching, such as holding hands or finding a new partner (Barker 2004).

  • In general, students have difficulty developing an adequate conception of the chemical combination of elements until they can interpret combination at the molecular level (Driver et al. 1994).

Energy and Chemical Bonds

  • It is very common to say there is energy in chemical bonds, and that when these bonds are broken, energy is released. But it is actually the opposite. Energy is released when chemical bonds are formed (Nordine 2016).

  • Misconceptions about energy and chemical bonds exists in life science as well as chemistry. Many students think that in biological processes, chemical bonds store chemical energy and that when these bonds are broken, the energy is released (Cooper and Klymkowsky 2013).

  • A common misconception is that energy is stored in the bonds of substances and released when the bonds are broken, much
    like water leaking out of a broken pipe (Millar 2005).

  • In a study by Boo (1998), a majority of high school students in the study were unable to predict the overall energy change in five different chemical events because of their misconceptions about the nature of a chemical bond. A large number of these students thought a chemical bond was a physical entity that linked atoms together. This physical notion of a chemical bond as being composed of matter thus appeared to be linked to the everyday notion that building any structure requires an input of energy. Therefore, the converse (destruction) is viewed as releasing energy. This seems to form the basis for the commonly held idea that bond making requires input of energy and bond breaking releases energy. Twenty-three out of the 48 students in the study (48%) held this belief.

Use of Models

  • Students have difficulty interpreting the use of ball-and-stick models for ionic lattices. Twenty-seven Australian 17-year-olds were interviewed in a study by Butts and Smith (1987) using a ball-and-stick model of sodium chloride. Students confused the six sticks around each ball as “one ionic and five physical bonds.” Only two of the students mentioned that the sticks were used merely to hold the balls in place in the model.