This is the new updated edition of the first book in the bestselling Uncovering Student Ideas in Science series. Like the first edition of volume 1, this book helps pinpoint what your students know (or think they know) so you can monitor their learning and adjust your teaching accordingly. Loaded with classroom-friendly features you can use immediately, the book includes 25 “probes”—brief, easily administered formative assessments designed to understand your students’ thinking about 60 core science concepts.

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The purpose of this assessment probe is to elicit students’ ideas about chemical bonds. The probe is designed to find out how students interpret molecular models.

Friendly talk

Atoms, molecules, chemical bond

The best answer is Will’s: I think a chemical bond is an attractive force between atoms in a molecule. Two or more atoms in a molecule are linked together by chemical bonds. There are several types of chemical bonds, including covalent bonds, ionic bonds, metallic bonds, and hydrogen bonds. Covalent bonds are formed between atoms in a molecule as a result of an electrical attraction between their electrons. The bond exists as an attractive force between the atoms, where one or more electrons are shared. Molecular models, such as the one shown in the picture, are representations of molecules. Models have limitations because they do not represent all aspects of the real thing. For example, a ball-and-stick model uses sticks to represent the attractive force between atoms. Structural diagrams use lines between symbols of atoms to represent bonds. The sticks and lines are physical structures intended to represent an attractive force, but the actual bond represented by the stick or line is not a physical structure.

Elementary Students

The concept of chemical bonds exceeds expectations for students at the elementary level. However, upper elementary students may have seen representations of molecules and may begin to form the idea that there is a structure or “glue” holding particles together.

Middle School Students

In middle school, students develop the idea that atoms join together to form molecules or crystalline arrays. They encounter the term chemical bond in both life science and physical science and have a concept of atoms being joined together. However, an understanding of the types of chemical bonds and the mechanism by which electrons are shared or transferred, resulting in an attraction that holds atoms or ions together, exceeds expectations at the middle school level. Students at this level see a variety of representations of molecules and ionic substances, including ball-and-stick models, which may contribute to their conception of a physical chemical bond. They should learn that models are representations that help us understand things but do not always represent all aspects of the real thing.

High School Students

Students at this level develop a deeper understanding of the microscopic nature of molecules, atoms, and parts of atoms, including the types of chemical bonds formed by the interaction of electrons. The nature of the atom, including electrical interactions with other atoms, is still an abstract, difficult idea for many students. Because representations of molecules and ionic compounds, including physical models and symbolic drawings, are commonly used in high school science, it is important to take the time to determine whether students have a conception of a chemical bond as a physical entity or a force of attraction. Many students can define the types of chemical bonds and the mechanism by which atoms are joined together yet still harbor the common misconception that a chemical bond is a structural component of an atom or a glue-like form of matter.

This probe is best used in grades 6–12. If materials are available, consider demonstrating the probe scenario with a ball-and-stick model or a drawing of a structural formula.

• 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).
• 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.

Burgmayer, P. 2011. A tale of four electrons. The Science Teacher 78 (2): 53–57.

NSTA Science Object, Explaining matter with elements, atoms, and molecules: Evidence for atoms and molecules. http://learningcenter. nsta.org/resource/?id=10.2505/7/SCB-EAM.3.1.

Hibbit, C. 2010. The romance of the atoms: Animated atomic attractions. Science Scope 34 (4): 48–51.

Mayer, K., and J. Krajcik. 2017. Core idea PS1: Matter and its interactions. In Disciplinary core ideas: Reshaping teaching and learning, ed. R. G. Duncan, J. Krajcik, and A. E. Rivet, 13–32. Arlington, VA: NSTA Press.

NGSS Archived Webinar: NGSS Core Ideas—Matter and Its Interactions, http://learningcenter. nsta.org/products/symposia_seminars/NGSS/ webseminar27.aspx.

Robertson, W. C. 2010. Chemistry basics: Stop faking it! Finally understanding science so you can teach it. Arlington, VA: NSTA Press.

• An additional probe that can be used to uncover students’ ideas about energy involved in chemical bonding is “Energy and Chemical Bonds” in Uncovering Student Ideas in Physical Science, Volume 3 (Keeley and Cooper 2019).
• The use of anthropomorphic analogies to explain how bonds form should be avoided. These analogies give students false ideas about atoms “wanting” to form bonds, “needing” a certain number of electrons, or “finding a partner.” The analogies tend to confuse organisms’ behavior with chemical behavior (Taber 1996).
• When using representations such as symbolic drawings of compounds and ball-and-stick models, explicitly state that the lines or sticks do not represent actual physical structures at the atomic and molecular levels.
• Connect the idea of representations of chemical bonds to students’ understanding of how models are used to represent structures and phenomena. Provide an opportunity for students to critique the representations of molecules and ionic compounds, describing the limitations of representations in depicting an actual molecule or ionic compound.
• Taber (1997) suggests that bonding should be taught from an electrostatic perspective— that all types of bonds are similar in that they all involve electrostatic attraction. Different bond types arise from the different particles involved. The point is to emphasize the commonalities between bonds rather than the differences.