Reply to the ‘Comment on “What resources do high school students activate to link energetic and structural changes in chemical reactions? – A qualitative study”’ by K. S. Taber, Chem. Educ. Res. Pract., 2024, 25, https://doi.org/10.1039/D3RP00232B

Abstract

Our article “What resources do high school students activate to link energetic and structural changes in chemical reactions? – A qualitative study” was recently commented on by Keith Taber. In his comment he focuses on the dominant role of the octet rule in students' reasoning and suggests that students rely on an octet framework. In the first part of this response, Taber's argument about the pervasive inappropriate use of the octet rule is supported by empirical evidence. Re-analysis of the data confirms that students often seem to assume initial atomicity, use anthropomorphic language, and closely associate the octet rule with stability. These points make the octet rule a convenient answer for students to fill the “explanatory vacuum” often left in chemistry education, e.g. for explaining the driving force of reactions. In the second part, we discuss how these observations might be rationalized. Rather than a static misconception perspective, we suggest that student's application of the octet rule can be viewed from a dynamic, resource-oriented view of learning. Three examples are introduced to illustrate the variety in students’ applications of the octet rule. For a better understanding, more detailed research on how students really think and learn about the octet rule and energetics is necessary.

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Introduction

Keith Taber (2024) recently commented on our article “What resources do high school students activate to link energetic and structural changes in chemical reactions? – A qualitative study” (Pölloth et al., 2023a). In his comment, Taber elaborated on one of our empirical findings: the high school students rationalized the driving force of a reaction most commonly with reference to the octet rule. Taber proposes that many students rely on an “octet framework” to explain central aspects of chemistry. He highlights that this is a major challenge for chemistry education, because it concerns “the central notion of chemical change”.

We thank Taber for pointing out the importance of this finding and his in-depth analysis of possible reasons. The prominent role of student argumentation with the octet rule has already caught our attention at first sight. Due to the focus on the energy concept in our original article, a more detailed analysis of these findings was out-of-scope. Hence, this reply aims for the following goals:

1. The empirical findings on student use of the octet rule in our preliminary study are elaborated on. Therefore, the entire data set was re-analysed. This analysis provides a broader base for discussing the role of the octet rule.

2. Taber mentions that the original article did not specify how the octet rule is taught in Germany. Hence, we give a few more insights into typical teaching on the octet rule in German high school.

3. Based on these insights, we address the questions raised by Taber: “Why do so many students seem to misunderstand/misapply this heuristic?” and reflect on “whether the teaching around this rule needs to be revisited”. Furthermore, we comment on the question if student argumentation should be seen as coherent.

4. The central goal of this reply is to strengthen Taber's call for more research on this topic.

Empirical results on students’ use of the octet rule

In our study (Pölloth et al., 2023a) we mainly discussed how students used the octet rule to rationalize the reaction of chlorine and hydrogen. Herein, vice versa, we focus on the question how students understand and rationalize the octet rule itself.

Method

Full details on sample, data gathering, and data analysis are reported in Pölloth et al. (2023a). For this reply the data material of the interviews was re-analysed. Therefore, all parts referring to the octet rule were analysed in a structuring qualitative content analysis (Kuckartz, 2016). All groups were assigned colours in the original paper and are named accordingly in here.

Results

In total, 8 out of 16 focus groups referred to the octet rule already in their initial explanation on why elemental chlorine and hydrogen react. Additionally, group Turquoise and group Plum used the octet rule later in the interview to explain stability. Yet group Magenta and group Lime referred to it to rationalize their formulation “the atoms want”. Hence, 12 out of 16 groups were discussing the octet rule despite the fact that it was not necessary at all in order to answer the guiding questions on reaction energetics.

This underlines the prominent role the octet rule plays in the reasoning of many high school students. In his comment, Taber points out three characteristics that are frequently associated with the use of the octet rule in students’ reasoning: anthropomorphic language, the assumption of initial atomicity, and confusion of stability and the octet. Our analysis shows that all three characteristics were common among our participants. Taber provides descriptive examples and profound analyses in his comment. These findings are illustrated with complementary examples of student responses and further questions to be investigated are identified.

Initial atomicity

From a scientific perspective, the application of the octet rule is only meaningful if molecular reactants are considered to be atomic. Otherwise, it would be obvious that most molecules already have full outer shells. Indeed, the argumentation for six of the focus groups in the sample suggest assumptions on atomicity of the reactants:

“Yes, you must have eight electrons. And if chlorine has seven and hydrogen has one electron, then they add up to eight, so that they are full/” (Group Black)

Some students even specifically discussed whether the reactants are atomic:

“3: Chlorine is molecular, isn't it? So, it doesn't occur atomically, hence Cl ₂ .

2: Yes, it does.

3: No.

2: Chlorine/Of course in atomic form/Oh/

3: No.

2: No, it doesn't occur atomically. True/Then it probably has seven/

3: Yes.

2: Thank you.” (Group Green)

Student 2 herein starts with the assumption that the reactants are atomic. However, they quickly accept that chlorine has to be molecular. Interestingly, this insight does not change their assumption regarding the number of outer electrons. Moreover, as the interview progresses, even student 3 confirms the assumption on seven electrons which leads them to apply the octet rule. Indeed, they presented their results a few minutes later as follows:

“2: And it happens because the hydrogen and the chlorine have both failed to fulfil the octet rule and they want to fulfil it so that their outer shell has eight electrons. And that's why they combine, always one hydrogen and one chlorine” (Group Green)

This reasoning suggests that the students are assuming atomicity, even though the same students have ruled out the possibility of chlorine being atomic.

Indeed, many student arguments in the interview seemed to imply atomicity of the reactants. However, it remains open if students really assume the reactants to be atomic or whether these arguments rather origin from the students’ unidimensional and fragmented thinking (Grove and Bretz, 2010). The main problem does not seem to be a lack of knowledge about the molecular structure of the reactants but the use of this idea and its consequences in a stringent line of argument. It is a central challenge of the chemistry education research community to investigate in more detail how the formation of such unproductive knowledge can be avoided and how a productively usable structure of conceptual understanding can be fostered (Holme et al., 2015).

Anthropomorphic language

As a second point, Taber highlights that students frequently use anthropomorphic language when discussing the octet rule. Indeed, the use of anthropomorphic language was very dominant in our sample. Eight of the groups used animistic language:

“If this chlorine had a full outer shell here, then it would be satisfied. But if it only has this point here, i.e. only seven, then it really wants another one, which means it's also looking for it.” (Group Turquois)

Nevertheless, several groups were also aware that their formulation did not meet the expected level of scientific explanations, e.g., by stating:

“Hm, an atom usually wants to achieve a noble gas configuration. […] And so this desire comes more practically from the fact that it is energetically more favorable this way…” (Group Green)

“It is, in quotes, satisfied.” (Group Orange)

Again, it seems that students are aware that their “anthropomorphic explanations are not valid in chemistry” (Taber, 2024). Some of them even explicitly point out the limitations of their arguments. Nevertheless, anthropomorphic language seems to be ubiquitous in high school chemistry. And even in universities, anthropomorphic language is omnipresent and used across science disciplines. However, there seems to be a difference whether students (but also experienced scientists!) really think anthropomorphically or whether this kind of language is rather used as a model being aware of its limitations (Taber and Watts, 1996). Indeed, there are divergent empirical findings on the extent to which anthropomorphic language is a barrier to learning or whether it can also be helpful in constructing scientific explanations (Tang and Hammer, 2024). It appears that anthropomorphic thinking is particularly compatible with the octet rule, because ‘wanting eight electrons’ sounds like a reasonable idea. However, it could also be argued that animistic language could serve as a bridge for conceptual change. If this language is clearly identified as a model, it could be filled with new rationalizations about the driving force of reactions. It seems worthwhile to investigate the use of anthropomorphic language in more detail.

Stability and the octet

Since we anticipated references to the octet rule, we implemented follow-up questions in our interview guide for the semi-structured interviews (Pölloth et al., 2023a, Appendix 1). The eight focus groups that mentioned wording like “octet rule”, “full outer shell” or similar during the initial discussion phase were asked at the end of the interview: “What is the advantage of such an electron octet/full outer shell?” (Interviewers adopted wording to fit students’ wording). Almost all groups answered this question with reference to the number of electrons in the outer shell. Throughout the focus groups, the words “octet rule” and “full outer shell” were used interchangeable before. Nevertheless, the full outer shell was used by many students to justify the octet rule:

“3: Yo, it's somehow about the electrons.

2: Electron octet. It's always about eight/So on the one hand, the valence shell is filled.

1: Yes, the outer shell.

2: Exactly, and that an electron octet is achieved in a molecule.” (Group Brown)

The students in this example used several scientific synonyms (electron octet, full valence shell, full outer shell, eight electrons) to rationalize one of the other terms. Thus, many of these arguments seem repetitive. Indeed, three groups did not move beyond this level of argumentation.

The five other groups further explained the octet rule in terms related to stability like “stable”, “less reactive”, or “energetically favorable state”. However, the reasons for this stability were explained in different ways. Several groups referred back to the electron configuration. Others referred to an equilibrium of forces between electrons and nuclei, when the octet rule is fulfilled. Others stated:

“2: Then it's a noble gas. And then it's somehow (…) a less reactive molecule?

I: Erm, when you say it's a noble gas, what do you mean?

2: Ok, it's not a noble gas, but it has a full outer shell and then it is/yeah.” (Group Green)

This answer illustrates well the problems students have in justifying the octet rule. Most of the time, words like “stable”, “less reactive”, or “energetically favorable” are used as buzzwords in a circular argument:

“I: And is stability or a stable state somehow related to energy?

2: (thinking) umh, you know with the periodic table and then the seventh/or eighth main group, that everyone wants to have um full outer/outer circles. Um, I would say that's related to that […]

I: What is the advantage of having a noble gas configuration like that/

2: Erm. Yes, the atoms are saturated, so to speak. I think that's what it says. So/

I: How do you mean saturated?

2: This full outer shell, they have/

1: This makes the atoms stable.” (Group Turquois)

As in this example, students very often rationalize “stability” by the “octet rule” and, vice versa, the “octet rule” by “stability”. Similar results are reported by Joki and Aksela (2018). Hence, no focus group was able to explain the octet rule in a satisfactory way:

“The two reactants here are very compatible. But I would say that if there are not eight electrons, a substance is very reactive because it is striving for a stable state. But otherwise I don't know…” (Group Purple)

Use of the octet rule in German high school chemistry education

Taber (2024) argues that the omnipresence of the octet rule in student argumentation is most likely a product of the way chemistry is taught. Therefore, we want to discuss briefly how the octet rule is commonly taught in Germany. A distinctive feature of the German education system is its federal structure. The curricula of the 16 German federal states differ considerably from each other.

Examining the curriculum of the state of Baden-Württemberg, where the interview study was conducted, it becomes evident that the octet rule, referred to as the “noble gas rule,” is explicitly mentioned in the curriculum for the 9th grade (Ministerium für Kultus, Jugend und Sport Baden-Württemberg, 2022). As in other federal states, the octet rule is introduced in the context of “molecule formation through electron pair bonding” that is expected to be explain by “applying the noble gas rule” (Ministerium für Kultus, Jugend und Sport Baden-Württemberg, 2022). In other federal states, the noble gas rule is introduced to determine the valence electron count of atomic ions and valence bond formulas: “The noble gas rule states that atoms of elements other than noble gases reach noble gas configuration when the number of valence electrons changes in a chemical reaction” (Staatsinstitut für Schulqualität und Bildungsforschung Bayern, 2018). The concept that the noble gas rule “is used to interpret reaction and binding behaviour” is also explicitly found in some curricula (Hessisches Kultusministerium, 2024).

When comparing high school textbooks, which are mostly controlled by the respective Ministries of Education, it is noticeable that the wording often suggests that the noble gas configuration is reached as a “stable state.” For example, a textbook states: “In the electron pair bond in molecules, the atoms are held together by shared electron pairs. This allows the atoms to achieve the more stable noble gas configuration” (Bohrmann-Linde et al., 2019). The occurrence of chemical bonds is rarely discussed in terms of energy changes. Bond energies and bond formation are rather considered and explained as static properties. However, it is noteworthy that anthropomorphisms are seldom found in textbooks. Therefore, the assumption arises that anthropomorphising occurs in classroom discussions, portraying bonds as “social agreements between atoms” to simplify students' understanding of abstract processes.

In university level chemistry textbooks (e.g., Binnewies et al., 2016; Wiberg et al., 2017), on the other hand, the noble gas rule plays a minor role and is often only marginally addressed even in comprehensive textbooks. Thus, the impression remains that the octet rule is overrepresented in German high school chemistry. Following the slogan “Teachers teach as they were taught, not as they were taught to teach” (Altmann, 1983 as cited in Schneider et al., 2013), this overrepresentation seems to persist throughout teacher training and is later reflected in the role of educators. This presumption is reinforced by the results of the interview study, where seven groups used the technical term “octet rule”, even though the word itself was not found in any of the analysed school textbooks. Therefore, it is most likely that the term was used and passed down by teachers.

Why do so many students seem to misunderstand/misapply the octet rule?

Based on the reported insights, some answer fragments are now given to Taber's question: “Why do so many students seem to misunderstand/misapply the octet rule?” The answers are not intended to be comprehensive and are partially based on literature (Taber, 2013a).

The octet rule is convenient for students

The problem does not seem to be that students – as well as teachers – do not understand the octet rule but rather that they understand it too well. The octet rule is very easy to understand and to apply. Nevertheless, it appears to offer a convenient explanation that is well compatible with anthropomorphic thinking.

The octet framework sounds scientific to students

It seems that the use of wording like electrons, shell, particle level makes the octet rule a scientific explanation to students. Indeed, the wording used by students is similar to wording in scientific books.

The octet rule plays an inappropriate role in chemistry lessons

The argumentation on the role of the octet in chemical reactions is not only found among high school students. In an unpublished study, we repeated our investigation with teaching degree students in our university. It was found that chemistry students reason about the octet rule and the driving force of reactions in a surprisingly similar manner as high school students. Above we showed how school books and curricula still implement the octet rule in a questionable manner. Taber (2024) gave a comprehensive overview how the octet rule is also used in different international educational settings. Hence, it can be assumed that the octet rule is used in an overgeneralized way in chemistry classes around the world.

The octet rule is learned early

At least in many German chemistry curricula (see above), the octet rule is taught early in chemistry classes. It was shown for other contexts that initially learned ideas can be very persistent (Bučková and Prokša, 2021). This is further emphasized through the wording “octet rule” (German: Oktettregel, Edelgasregel) which implies a specific significance and general validity.

Students lack alternative patterns of arguing

From our point of view, one very important point for the dominance of the octet rule is that students often lack other cognitive resources that could help to formulate more scientific explanations of the driving force of reactions. As outlined in our article, most of the focus groups found answers to the questions concerning activation energy and the origin of the exothermic character very quickly – even though many answers remained stuck on a macroscopic level. In contrast, the question of why the chemical reaction occurs was very difficult to answer for the high school students. Despite discussing this question much longer than the other questions, most students were not able to elaborate on it. This is best described by Group Green:

“[The question why the reaction occurs at all] is actually interesting because when we used to look at experiments in school when you see a reaction you see straight away that it's a reaction and [you do] not [ask] why the reaction is happening.” (Group Green)

It seems reasonable that students fill this central “explanatory vacuum” (Taber, 2013b) by referring to the octet rule. Indeed, many students did not feel satisfied by their explanations themselves:

“I: But what is the advantage of this noble gas configuration?

2: That's a good question.

1: We never learnt that. I always asked that myself too.

2: So, it was always said, yes, there are//of course stable/

1: It's just like that. Chemistry is like that, but um/it was never explained . No chemistry teacher could explain it when you asked somehow.” (Group Purple)

If the central question of why reactions occur is not discussed in chemistry lessons, it is not surprising that students come up with their own explanations. However, this may be at the cost of making the learning of chemistry feel like something that is neither understandable nor logical for many students. Therefore, a clearer distinction between observations and a multidimensional perspective (structural, energetic, quantum mechanical) on the underlying principles should be considered. Before some specific conclusions for teaching about the octet rule and the driving force of reactions are given in the last chapter, some implications on the theoretical framework are discussed.

Can students' use of the octet rule be interpreted from a dynamic understanding of learning?

In his comment, Taber proposes that many high school students rely on an internally coherent “octet framework”. In this context, many central topics of chemistry – like bonding, non-covalent interactions, and chemical reactivity (Taber, 2013a; Taber, 2024, Fig. 1) are considered to be linked to the central node “octet rule”. In our original article, we referred to a resource-based framework (Hammer et al., 2005; diSessa, 2018). It is assumed that learners activate diverse cognitive resources (e.g. from learning or from everyday experience) dynamically to solve a specific problem.

Consequently, the utilisation of the octet rule by students can be characterised as either a coherent misconception or as the outcome of a dynamic sensemaking process. Taber states:

“Given the extensive research-base now available it seems reasonable to state that learners’ alternative thinking about natural phenomena varies along this dimension [‘theory-like’ vs. isolated notions] such that it can sometimes be, but is by no means always, theory-like . Indeed, this characterisation applies to people's thinking more generally.” (Taber, 2024, emphasis by the author)

We fully agree with this statement. The discussion if students’ knowledge structure is fully coherent or completely fragmented is fruitless (diSessa, 2014a). Nevertheless, we argue that a dynamic view of learning and problem-solving can help to understand how an idea like the octet rule can become dominant in students’ thoughts and arguments. For example, Gouvea and Simon (2018) showed in a remarkable study that several well-known “coherent alternative frameworks” in biology education are interpreted more productively from a dynamic point of view. Similarly, we think that an interpretation of students’ reasoning around the octet rule from a dynamic perspective can prove to be more beneficial, even if students’ arguments seem to be coherent at first glance. Our suggestion is supported by the following three examples.

Group grey: the octet rule as the ‘correct answer’

Group grey showed a very typical argumentation pattern on the question why a reaction occurs. They argued:

“2: Okay, so, um, individual chemical elements always try to have eight valence electrons. Is that right? And, um, they can't fulfil that on their own, but if they form a bond with another element, then they can fulfil it together, so to speak. And since hydrogen is in the first main group, that means it has a valence electron. And chlorine […] has seven valence electrons and together they have eight. And that's why they react so readily.” (Group Grey)

Students’ wording appears to combine the octet rule, chemical bonding, and reactivity into a coherent explanation of the reaction processes. Indeed, the reasoning aligns very well with the octet framework as presented in Fig. 1 of Taber (2024). But how did students arrive at this answer? The group discussion phase provides interesting insights:

“2: Why does a reaction occur at all?

1: That's a good question, why do they react with each other?

3: Wait a minute/

1: It's very, very reactive.

3: Hydrogen is in the first main group and that's yes/Chlorine is in the […] seventh. And then/

2: Ah and then you can use the/What is it called? Octet rule.

1: Oh, yes. Yes, good. Yes.

2: You could/But I don't know/

1: Yes, they want/But/

3: That must be correct, right?

1: That must be true. They just want their eight outer electrons. And because they don't have them themselves, they form a bond. And share electrons with another partner.

3: And that's why they react.

1: And that's how they get their eight electrons, so to speak.” (Group Grey)

At first, the group is unsure how to argue. However, when they start thinking about the periodic table, the octet rule quickly comes to their minds. This could indicate a strong mental link between atomic structure and the octet rule. Once activated, the students seem to accept the octet rule as the “correct” solution (Bhattacharyya and Bodner, 2005). Hence, there appears to be no necessity to consider other arguments and models to describe the scientific phenomena.

Throughout the sample, many students articulate similar uncertainties while discussing the reason for the occurrence of the reaction and the role of the octet rule. Nevertheless, the final answers often sound like a coherent and confident argumentation based on an ‘octet framework’.

Group orange: constructing an octet-based “model”

Group orange starts their explanations very similar to group grey. However, they do not stop at this point but try to give further explanations:

“1: Um, if you now look at these two chlorine atoms, just two spheres, so to speak… If you look at it like this, this sphere […] has layers and in the outermost layer of this sphere a disc is missing.[…] And this little piece that is missing, this sphere tries, if you now visualize it completely, that it can really roll properly, it looks for itself for […] a second sphere, where a disc is missing, which you then put together so that it can then really roll properly. And this disc that is missing is precisely the […] last electron that is missing in the outer shell so that it has a noble gas configuration. And it is precisely this noble gas configuration that is the goal of every atom or molecule, so that it simply has the ability to roll, if you visualize it a little bit.” (Group Orange)

The student seems to dynamically construct their own framework based on an overinterpretation of the Bohr model in combination with the octet rule. Once this idea is introduced, they use it throughout the interview to explain a variety of different topics, such as the driving force of the reaction, stability, and their reasoning on the octet rule:

“1: This is approximately the stability. If a substance doesn't have the ability to perform the rolling movement that I have in the model, it looks for as many substances from the outside as possible. And as a result, the substance that can't roll doesn't stay the substance that can't roll for long, but it picks up something from outside.” (Group Orange)

It seems that the combination of the octet rule with the made-up visualization sounds like a coherent explanation to the student. Hence, the dynamically made-up “model” becomes the dominant idea in the student's argumentation.

Group gold: the octet rule as the default argument

Group gold is a very different example of the use of the octet rule. In particular, Student 2 was one of the strongest students in the sample, with a deep and scientifically accepted knowledge of energetics, including the Gibbs–Helmholtz equation. While student 2 did not refer to the octet rule throughout most of the interview, in one of the last comments they suddenly used the octet rule to argue about the reactivity of molecular species:

“1: Yes, because of the structure of the atoms. Because they have different//electron numbers (interrupted)/

2: Yes, that's why halogens react so well with alkali metals or with hydrogen, for example, exactly…” (Group Gold)

Linking reactivity to the octet rule does not seem to contradict the student's previous scientifically accepted argument, even though the students are aware of the octet rule's limitations:

“2: [The electron octet] is much more energetically favorable. We then had other molecules where this is not the case and which were quite unstable. I don't know, for example, um, carbon monoxide, or something like that?

3: But also here, I think, the same applies/

2: (quickly) Yeah, in that case it just explained that there's a triple bond because that's how the electron octet is achieved.” (Group Gold)

The student uses the “instability of CO” as an argument for the octet rule's relevance concerning the stability of molecules. Furthermore, they quickly revise their statement on CO as an exception of the octet rule as soon as it appears to be problematic.

Both of these short episodes from this student illustrate how flexible they use the octet rule in their arguments. However, it seems that from their point of view the importance of the octet rule surpasses many other concepts in chemistry.

A dynamic view of learning can explain the dominant activation of resources

These examples indicate that the dynamic view of learning might be more suitable to describe students’ thoughts than the static approach (Hammer et al., 2005). Accordingly, the frequent use of the “octet argument” by students and teachers could become self-amplifying because it is likely that a recently and frequently activated resource is activated even beyond the original context. This is consistent with the molecular biology of memory (Bliss and Collingridge, 1993; Kandel, 2001), which explains how synaptic connections are strengthened in the short term after use and persist with regular activation.

It should be noted that the examples given were not collected for the purpose of evaluating the dynamic nature of students' reasoning about the octet rule. Therefore, the examples are not intended as an empirical proof. Rather, they serve as an illustration on how students' arguments can be interpreted in different ways. Hence, there is a need for more detailed research on how students generate their arguments on chemistry problems (Parnafes and diSessa, 2013; diSessa, 2014b). Further research could provide a deeper understanding of the way specific resources, such as the octet rule, can become so dominant in students' reasoning.

Does the teaching around this rule need to be revisited?

To sum up, some implications for the teaching around the octet rule are derived.

Revising the teaching around the octet rule

Talking specifically about the octet rule, there seems to be some fundamental advice. The octet rule should be taught…

– as an observation (rather than a rule) from ionisation energies.

– as a useful tool to determine Lewis structures and likely ionisation states for second-row elements. Thereby, the formal nature of this approach should be clearly emphasized to avoid an overinterpretation as driving force.

– with clearly communicated limitations.

Although the octet rule plays a minor role in the analysed university level chemistry textbooks, many students seem to stick to their beliefs from high school. Especially for future teachers, it appears to be important to clearly discuss the limitation of the octet rule. Therefore, a better transfer of results from chemistry education research to chemistry teacher education and professional training is necessary.

Revising the teaching about energy in chemistry

However, it seems neither feasible nor sensible to change the teaching only around the octet rule. At the very least, the teaching of the core idea of energy needs to be revised (Cooper et al., 2017). Such teaching should aim at an interdisciplinary understanding of energy. If the content of scientific disciplines seems only barely connected (Abramovitch and Fortus, 2023), it is not a problem to accept the octet rule as a natural rule in chemistry. Indeed, a recent study showed that teaching science interdisciplinary – at least in the first years of learning science – can increase students’ understanding of energy (Dietz, 2023).

Furthermore, it seems important to clearly discuss the driving forces of reactions. At least in many German curricula, the question of why reactions occur is not explicitly discussed (Scholz, 2010; Kultusministerkonferenz, 2020). A profound implementation of energetic aspects, e.g. the specific discussion of bond energies and the calculation of reaction enthalpies, could avoid this “explanatory vacuum”.

Last, there is a need for new learning and teaching methods oriented at the state of the art of chemistry. While today's understanding of energy in the natural sciences is largely based on quantum mechanics, school chemistry is still based on ideas from the end of the 19th century. Hence, there is a need for discipline-based educational research exploring how novel ideas, e.g. quantum mechanics, could be implemented in teaching chemistry.

The way students think and learn in chemistry should be researched in a fine-grained manner

Finally, some of the issues discussed here do not seem to be specific to the octet rule. It appears that many high school students have very specific knowledge, but struggle to apply this knowledge to solve scientific problems. Comparable observations can be made for other topics in chemistry such as reasoning about chemical bonds (Galley, 2004; Hunter et al., 2022), or mechanistic problem solving (Graulich, 2015; Dood and Watts, 2023). It could be argued that the misapplication of the octet rule is not just a consequence of a minor misunderstanding of a scientific term, but rather a symptom of a central problem in chemistry education. While students’ difficulties with the octet rule were already reported 26 years ago (Taber, 1998), there is still a need to better understand why chemistry education often leads to unproductive knowledge rather than fostering problem-solving skills.

In this context it should be considered that the way students think is different from the way scientific theories work (diSessa, 2014a). Indeed, thinking is always ‘biased’ by context. Thus, more research is needed that investigates the way students think and learn in a fine-grained and detailed manner (Parnafes and diSessa, 2013; diSessa, 2014b). These results may allow to identify (over-)dominant links in students’ thinking (like the octet rule) as well as underdeveloped connections of cognitive resources. Because this varies between educational systems, different classes, and individual students also low-threshold tools should be developed that allow teachers to analyse students thinking just in time – also using new digital tools (Martin et al., 2023; Pölloth et al., 2023b). Such a detailed analysis of the way students think could crucially impact the way chemistry is taught, assessed (Stowe et al., 2021), and researched (Hunter et al., 2022).

Conflicts of interest

There are no conflicts of interest to declare.

Acknowledgements

The authors would like to thank Theresa Ott and Lena Baumann for proofreading.

Notes and references

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