Blog - Science-Education-Research

To the organising committee of the 4th International Biotechnology Congress 2020

Keith S. Taber

Dear Sophie

Thank you very much for your kind personal invitation to deliver a speech at the 4th International Biotechnology Congress (IBC-2020) to be hosted from Dubai, UAE.

I am fine, thank you for asking. I hope you are also well. As you are kind enough to ask after my family, they are well as far as I can tell: we are all isolating here, so I am not currently able to meet them physically. Since my wife died, I have lived alone – though of course I am never socially isolated given such regular personal attention from the wider scholarly community, such as yourself.

Given that "high qualified speakers will be selected from all over the world", I am obviously very honoured to be invited to speak at the International Biotechnology Congress. I certainly appreciate that "the participation of outstanding international experts" gives a conference such as this the potential to make a real contribution to a field.

However, I have looked through the tracks, and I really cannot see how my expertise would fit into any of these. Indeed, I really wonder if my own work qualifies me as a suitable invited speaker (with all the costs this could entail for the organisers) in this particular conference. I am not convinced that the other outstanding international experts in biotechnology will feel I really am actually a highly qualified speaker able to contribute much to inform their work. Of course, if you feel I am being too modest, and that you still do consider that my research and scholarship would be appreciated by the other delegates, then please do get back to me to explain where you feel my work would fit into the programme.

Otherwise, I wish your congress well, but suspect I should focus my energies on activities more closely aligned with my own research.

Best wishes

Keith

The 4^th International Biotechnology Congress 2020
Time: Nov. 9-11, 2020
Place: Dubai, UAE
Dear Keith S. Taber,
This is Sophie from organizing committee of The 4^th International Biotechnology Congress (IBC-2020). How are you? Hope you and your family are all fine now. We would like to make sure you did not miss our conference invitation! I'm writing to follow-up my previous invitation as below. I sincerely wish you could reply me with your answer about our invitation. Thank you very much.
We are proud to announce that the 4^th International Biotechnology Congress (IBC-2020) will be held during Nov. 9-11, 2020 in Dubai, UAE. On behalf of committee, we cordially welcome you to deliver a speech in our conference. …

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The Sun would pull more on the Earth…

Bert's understanding of the reciprocal nature of forces

Keith S. Taber

Bert was a participant in the Understanding Science Project. A key idea in school physics is that forces occur in pairs, when two bodies exert an equal magnitude force upon each other (as required by Newton's third law). However, this seems counter intuitive to pupils, who may expect that a larger (more massive, or greater charge etc.) object would exert a greater force on a smaller body than vice versa. In physics a distinction is made between the forces (always equal) and their effects (which depend upon the force applied, and the mass of the object being acted upon). This distinction is not always made by students.

When in Y11, Bert offered an example of one of the common alternative conceptions found among students – that the larger body will exert more force:

What about the Earth going round the Sun, that's an orbit as well is it?

Yeah.

…

So why does it go round?

Why does it go round?

Yeah.

Erm because erm, well one is the gravity of it pulling and the other is, I'm not so sure what the other force is.

That's gravity of what?

The Sun.

So the gravity of the Sun pulling on the Earth?

Yeah.

Do you think the Earth pulls on the Sun?

Yeah, I guess but not strongly enough to move the Sun. Because if there's an object with a small amount of mass then it's not going to give off as much pull as something ten times bigger as it. So the Earth would pull more on the Sun, I mean the Sun would pull more on the Earth.

Whereas the physics perspective is that a force is an interaction between bodies, Bert talks as though a force is something that emanates from one body to another ("give off … pull"), a way of talking quite common among students applying their intuitive understanding of force.

Many students conflate the force acting on a body, and its effect (the acceleration produced) – so here the Sun and Earth are subject to the same force, but the earth is much less massive so will accelerate much more subject to that force than the Sun would. (The Sun's acceleration would actually depend on the net force acting on it considering the various bodies in orbit around it.)

Common experience tells us that in interactions between contrasting bodies (e.g., consider a fly on a windshield) the larger object has more effect, which may seem naturally to mean it applies more force (how much force can the tiny fly impart? – surely the car must apply more force to the fly?) So there is an intuition here, which can act as a grounded learning impediment to learning the physics formalism.

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Are plants solid?

Keith S. Taber

Bill was a participant in the Understanding Science Project. Bill (a Year 7 pupil) told me Bill talked about how in his primary school he had studied "a lot about plants, and – inside them, how they produce their own food", and how "inside, it has leaves, inside it, there is chlorophyll, which stores [sic] sunlight, and then it uses that sunlight to produce its food."

Bill had been talking to me about particles, and I asked if plants had anything to do with particles:

Well in the plant, there is particles….'cause it's a solid…. inside the stem is, 'cause going up the stem there would be water, so that's a liquid. And, it also uses oxygen, which is a gas, to make its food, so. I think so.

I suspect that Bill's reference to the plant being "a solid" would seem unproblematic to many people, especially as Bill recognised the presence of water (a liquid) and oxygen (a gas) as well.

There is however a potential issue here. The model of states of matter and changes of state taught in school strictly refers to reasonably pure samples of particular substances (so water is a liquid at normal temperatures, and oxygen is a gas – although strictly speaking the air in which it is found is a mixture which is not best considered 'a gas'). A plant (like an animal) is a complex structure which cannot be considered as a solid (and indeed living things were separated out in distinct substances, water would make up much of the content).

If the scientific model of solids, liquids and gases is applied beyond the range of individual substances, this is sometimes unproblematic. To consider the air as a gas, or the sea as a liquid, is not usually a problem as it is clear what this means in everyday discourse. But of course it is not possible to find 'the' boiling point of complex mixtures such as these.

However a wooden stool is only a solid in the everyday sense, certainly not in a scientific sense, and to refer to animals or plants as solids does considerable violence to the concept. (BBC Bitesize – please note!*)

(* Read 'Thank you, BBC: I'll give you 4/5')

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There are particles in everything – but maybe not chlorophyll

Keith S. Taber

Bill was a participant in the Understanding Science Project. Bill (a Year 7 pupil) told me that "solids they stay same shape and their particles only move a tiny bit". He explained that the 'particles' were "the bits that make it what it is", although "you can't see them" as "they're very, very tiny". Later he commented that "they are microscopic".

Although it is very common for such particles to be said to be 'microscopic', a better term would be 'nanoscopic'. Microscopic suggests visible under a microscope, and the particles referred to here ('quanticles') are actually submicroscopic." The term microscopic could therefore be misleading, and it is known that often when students first learn about particles in science they often have in mind small grains of powder or dust.

Bill explained that "there is particles in everything". Bill was able to talk a lot about particles in solids, liquid and gases and explain what happened during melting.

Later in the same interview Bill talked about how in his primary school he had studied "a lot about plants, and – inside them, how they produce their own food", and how "inside, it has leaves, inside it, there is chlorophyll, which stores [sic] sunlight, and then it uses that sunlight to produce its food."

I asked Bill if plants had anything to do with particles:

Well in the plant, there is particles….'cause it's a solid…. inside the stem is, 'cause going up the stem there would be water, so that's a liquid. And, it also uses oxygen, which is a gas, to make its food, so. I think so.

Bill explained that "…in the leaves it is chlorophyll which is a green substance, so that would make, give it its colour".

Do you think chlorophyll is made of particles?
Hm, don't know.

So it seemed that although 'there is particles in everything', Bill did not seem to feel this meant that he could apply the particle idea to all substances. This could be an example of a fragmentation learning impediment: that is, where learning in one area is not recognised as relevant in studying other subjects or topics.

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Sodium has one extra electron in its outer shell, and chlorine is minus an electron, so by force pulls they would hold together

Keith S. Taber

Focal figure (Fig. 5) presented to Annie

She was shown a representation of part of a lattice of ions in sodium chloride (see: Sodium and chlorine don't actually overlap or anything), but Annie identified the signified as atoms, not ions, because Annie had an idiosyncratic understanding of what was meant by charge. (Read: Na+ has an extra electron in its outer shell and Cl- is minus an electron and K-plus represents a potassium atom that has an extra electron.)

Annie was asked whether the structure made up of sodium and chlorine 'atoms' would hold together:

Do you think this thing would fall apart? Or would it hold together?
(pause, c.9s)
If you heated it, or reacted it in some way, it would hold together, and it would probably get held together by just forces.
By forces. Any idea what kind of forces would hold it together?
Probably just the attraction.
Uh hm?
The attraction from the plus to the minus because like chlorine's minus an electron and sodium is over an electron. So they could just like hold them together, but not actually combine.
Right, chlorine's, so sodium's, say that about the electrons again.
Sodium has like one extra electron, 'cause it has like an extra electron in its outer shell, and chlorine has seven electrons in its outer shell so its minus an electron so by sort of exchanging, the sodium combining with the chlorine just by force pulls they would hold together.

So Annie saw the plus (+) symbol to mean one electron over a full shell (2.8.1), and the minus (-) symbol to mean one electron short of an octet of electrons (2.8.7). For Annie these charges were not net electrical charges, but deviations from octet configurations. Yet, these 'deviation charges', for Annie, provided the basis for the attraction between the 'charged' atoms.

This was checked by asking Annie about the electron configurations.

So we looked at a sodium atom earlier, you recognised it as being a sodium atom, …
Can you tell me what the configuration is in terms of shells? How many in the first shell, how many in the second shell…
2.8.1
2.8.1?
Yeah.
So this here (indicating a cation on the figure), you are saying that this here is 2.8.1
Yes.
And this is 2.8.7 would it be?
Yeah, 2.8.7
And that is what holds them together the fact that this is one short,
yeah,
one over and one short.
One over, and that one's one short.
So the plus means one electron more than an outer, the full shell,
Yeah.
and the minus means one electron
Minus.
less than an outer shell,
Yeah.
and that's what holds them together.
Yeah.
Okay, so there is something holding them together,
right,
and it's to do with these pluses and these minuses,
Yes.
but what we don't have there is chemical bonding like we had before.
No.

Annie held an alternative conception of the nature of the charges associated with ions: that neutral atoms had 'charges' if they did not have full shells/octets of electrons. Whilst Annie's specific deviation charge conception would seem to be rather unusual, alternative conceptions relating to the significance of full shells / octets of electrons seems to be very common among chemistry students. Although Annie's thinking was idiosyncratic it reflected the common full shells explanatory principle that sees electronic configuration as a cause for chemical processes.

So Annie considered that these 'deviation' charges could actually give rise to forces between atoms (see also The force of lack of electrons pulls two hydrogen atoms together*).

Annie did not see ions, but atoms. But she thought that after a reaction, there would be attractions, 'force pulls', holding the product together, but this would not amount to chemical bonding.

Annie's notion of 'charges' on atoms (being extra or missing electrons in the outer shell), that led to her not recognising bonding in the NaCl, was an uncommon alternative conception notion. However, her notion that chemical bonding was something other than 'just forces', and that sometimes structures were held together by 'just forces' when there was no bonding, is a common alternative conception. Indeed it is part of a common 'molecular framework' for conceptualising ionic bonding, that is in turn a part of a common alternative conceptual framework for thinking about chemical bonding, stability and reactions: the octet framework.

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Na+ has an extra electron in its outer shell and Cl- is minus an electron

The plus sign shows Na⁺ has an extra electron in its outer shell; the minus sign shows Cl^– has seven electrons in its outer shell so its minus an electron

Focal figure (Fig. 5) presented to Annie in interview

She was shown a representation of part of a lattice of ions in sodium chloride (see: Sodium and chlorine probably get held together by just forces*), but Annie identified the signified as atoms, not ions:

Any idea what that’s meant to be?

(pause, c.6s)

Just sodium and chlorine atoms.

As an A level student, Annie would be expected to understand the differences between atoms, ions and molecules, and to known that there were ions in NaCl, but this could have been a simple slip of the tongue. This was tested by further questioning:

Erm, so if you look at these, I mean you said they were sodium and chlorine

Yes.

because presumably you recognise the Na and the Cl,

Yeah.

but only two of them are labelled with ‘Na’ and ‘Cl’.

Yes.

What about the others – what do you think they are?

They’re probably sodium and chlorine, or else they could be, because of the signs, you’ve got plus and minus signs on them representing the charge, or else it could be similar elements going down the groups.

Okay, so you recognise that these, these things represent charges, and you probably guess it’s just me being lazy that I haven’t labelled them all, [Annie laughs] so I’ve just labelled the first couple, erm, so these are what, so you reckon this little one will be, what will that be do you reckon?

Sodium.

That will be a sodium, molecule?

Atom.

Sodium atom, what about this one here?

Chlorine atom.

That’ll be an atom. But these have got charges on?

Yeah.

So Annie recognised the symbols for positive and negative charges, and thought that the figure signified atoms, with charges. The simplest interpretation here is simply that Annie did not recall that atoms were neutral, and 'charged atoms' are called ions in chemistry.

However, Annie then told me that sodium has like one extra electron in its outer shell, and chlorine is minus an electron, so by force pulls they would hold together, and explained this in terms of her notion of charges:

…say that about the electrons again.

Sodium has like one extra electron, ‘cause it has like an extra electron in its outer shell, and chlorine has seven electrons in its outer shell so its minus an electron so by sort of exchanging, the sodium combining with the chlorine just by force pulls they would hold together.

So Annie saw the plus (+) symbol to mean one electron over a full shell (2.8.1), and the minus (-) symbol to mean one electron short of an octet of electrons (2.8.7). For Annie these charges were not net electrical charges, but deviations from octet configurations. These 'deviation charges', for Annie, provided the basis for the attraction between the 'charged' atoms.

This was checked by asking Annie about the electron configurations.

So we looked at a sodium atom earlier, you recognised it as being a sodium atom, I did not say it was, and that had an electronic configuration of…do you remember what the electron configuration was?

Eleven.

So a total of eleven electrons

Yeah.

So do you know what shells they were going to?

Sorry?

Can you tell me what the configuration is in terms of shells? How many in the first shell, how many in the second shell…

2.8.1

2.8.1?

Yeah.

So this here (indicating a cation on the figure), you are saying that this here is 2.8.1

Yes.

And this is 2.8.7 would it be?

Yeah, 2.8.7

Annie held an alternative conception of the nature of the charges associated with ions: that neutral atoms had charges if they did not have full shells/octets of electrons. That this was a general feature of her thinking became clear when she was asked about the symbols for other ions: such as K⁺ and F^–.

Whilst Annie's specific 'deviation charge' conception (i.e., that (neutral) atoms would be charged when they did not have fill shells/octets of electrons) would seem to be rather idiosyncratic, alternative conceptions relating to the significance of full shells / octets of electrons seems to be very common among chemistry students.

Although species with Annie's deviation charges did not have actual overall electrical charge, Annie considered that these 'deviation' charges could actually give rise to forces between atoms (she thought that as sodium has one extra electron in its outer shell, and chlorine is 'minus an electron', then they would hold together; The force of lack of electrons pulls two hydrogen atoms together⚗︎).

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Calcium and oxygen would not need to bond, they would just combine…

Calcium and oxygen would not need to bond, they would just combine, joining on to make up full shells

Keith S. Taber

Annie was a participant in the Understanding Chemical Bonding project. She was interviewed near the start of her college 'A level' course (equivalent to Y12 of the English school system). Annie was shown, and asked about, a sequence of images representing atoms, molecules and other sub-microscopic structures of the kinds commonly used in chemistry teaching. Near the end of the interview, she was asked some general questions to recap on points she had made earlier. She suggested that Ca²⁺ and O^2- would combine, but without any chemical bonding.

Could you have a double ionic bond?
(pause, c.3s)
Can you have a double bond that's ionic?
Not really sure.
If you had say, say you had calcium, two-plus (Ca²⁺), and oxygen two-minus (O^2-),
yeah,
could that form a double bond?
(pause, c.4s)
Are you not sure?
It wouldn't need to.
It wouldn't need to?
No.
Why's that?

Because one's lacking two electrons, and one's got two, so, they would just combine without needing to sort of worry about other, other erm elements.

Right so they…
Sort of joining on to make up full shells.
So they combine, but you wouldn't call that a chemical bond?
No.

From what Annie had reported earlier in the interview, she would see Ca²⁺ as a calcium atom (that's "got two" electrons in its outer shell) and O^2- as a oxygen atom (that was "lacking two electrons"), as she held an alternative conception of what was meant by the symbols used to indicate electrical charge plus and minus signs represent the charges on atoms)*.

Annie here suggests that the atoms with their charges (i.e., for Annie, deviations form full shells) would combine, and join up to obtain a full shell. From her perspective, there was no need for ionic bonding. Although Annie's notion of what was signified by the charge symbols would seem to be idiosyncratic, the idea that chemical processes occur to allow atoms to obtain full shells (the 'full shells explanatory principle') is one of the most common alternative conceptions in chemistry.

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Atoms evolved so that they could hold on to each other

Bert Suggests Chemical Bonding Evolved

Keith S. Taber

Bert was a participant in the Understanding Science Project. During one interview he reported that he had just completed a topic of alkanes and alkenes in his chemistry classes. He explained that a carbon atom has "to have four bonds", so if a carbon atom had "only got one two carbons on one side and one hydrogen then it'll make a double bond, to have four bonds". So I asked him what he understood a bond to be:

I: …what's a bond?
B: A bond is erm, it just, it's something to hold, hold two atoms together.
I: So what might you use to hold two atoms together?
B: Erm, So they can be kept, so that they're not too, I think it's just to make, so it can make big lines so it can erm, oh, so they, so not every, so because solids they have erm, I guess a lot of bonds, to keep it all, all together, I'm guessing. And erm like gas has a lot less bonds because it's a lot more free.
I: That makes sense [Bert], I'm just wondering what you would use to bond two atoms together. … I'm just wondering what kind of thing you use to bond two atoms together.
B: Erm • • I'm not sure. I guess, I guess they were just, when er, they're made with it I guess.
I: Yeah. Do you think it's made of adhesive? … is it made of a glue do you think?
B: No, I don't think so. I think it was like, I don't know, it could have been like evolution, like.
I: Ah.
B: Yeah, the atoms evolved so that they could hold on to each other.
I: Oh I love that. • • • The atoms evolved so that they could hold on to each other?
B: I guess so. That's how the world was made.

In this interview segment Bert seems not to have considered the nature of the bonds between atoms, but just to have accepted what he has learnt about valency. When asked about the nature of the bond he could offer no mechanism for bonding, but instead suggested that chemical bonds had evolved as "that's how the world was made". Here Bert is drawing upon a general explanation considered to be universal in the domain of living things, but applying his learning from biology to explain a physical phenomena.

This seems to be a creative association drawing upon prior learning, but the idea of evolution is being used outside is canonical range of application, leading to a potential associative learning impediment. Potentially, Bert's thinking about evolution as explaining how atoms can bond (a potential explanation about origins, though inappropriate if evolution is understood as natural selection) could stand in place of seeking a physical explanation for the nature of bonding.

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Guessing what is produced in beta decay

Keith S. Taber

Forgetting the source?

Interestingly, in a later interview just before her GCSE examinations, Amy told me: "beta radiation is, I dunno, an electron – thing, which is emitted somehow." When I asked her where's it emitted from, she told me

"that's what I don't know, 'cause I asked about that, and I didn't get an answer because, erm, apparently the neutron is made up of other stuff, and it, that sort of decays to give other things and that's where the electron comes from, apparently, maybe, I don't know, I'm guessing now".

When asked if she knew what else was emitted, Amy suggested that "I'm guessing proton, but I don't know". It seems this had seemed so 'crazy' that Amy was not able to believe what she had been taught, and what had previously been reported as something she had been told, was now considered by her to be just a guess at what was going on. This is an interesting reminder of how human memory works, that we do not always recall the origins of our ideas, so can not always distinguish our own creative ideas from we might have been previously told at some point.

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Crazy physics: radioactivity is just mad!

Some crazy thing about a neutron turning into a proton or something

Keith S. Taber

Amy was a participant in the Understanding Science Project. I talked to her after she had just started studying radioactivity in her Y11 physics class. She had been introduced to alpha, beta and gamma radiation, and the teacher had been telling the class crazy things: "he told us some crazy thing about a neutron turning into a proton or something, and losing, two electrons or some crazy thing like that."

This was crazy because "it doesn't make any sense". Amy had only just started the topic, and had not yet sorted out all the details in her own mind, but the teacher had "showed us this little equation thing they [sic] have, and when – is it the electrons that are released or something – the atom, it changes, it changes into something else". This was not something else other than an atom, but "an element will become a different element or some stupid thing like that". Amy concluded that "all of it sounds crazy, physics is crazy. I don't understand it." This seemed a rather harsh judgement.

Amy was generous enough to talk to me regularly about her understanding of the science she was taught in school. She, regularly, told me she knew or understood little about the topics she was taught, although a little probing often revealed considerable learning. However, on this occasion, Amy genuinely seemed to be genuinely mystified by what she was being told.

I spent a little time talking to Amy about radioactivity. I discussed beta decay with Amy, concluding with "an electron comes shooting out of the atom, and that's your beta radiation". Amy maintained "it's crazy". We discussed the different types of radioactivity she would study: "it's crazy". I think Amy believed what I was telling her, but she made it clear what she thought of these nuclear changes and the accompanying transmutation of elements: "it's mad"!

What I find especially interesting here, is that Amy seemed to have strong intuitive views of the way the world should work, even when the focus was something so far from our everyday experience. Atoms, nuclei, electrons, neutrons, protons, are all theoretical constructs we introduce to students that have no obvious and clear link with anything in everyday experience. They also behave in ways unlike objects of common experience. It can only have been a couple of years since Amy was taught that atoms had structure and comprised of protons, neutrons and electrons. But now she readily accepted that neutrons existed. Indeed they had become so 'real' to her, that the idea one must spontaneously change into a proton and an electron seemed quite mad. So Amy had relatively quickly applied her intuitive ideas about the way the world is to form a mental model of a neutron as a discrete, stable entity: not something that could suddenly reveal itself as potentially two other things that were supposed to be quite different. When Amy was introduced to a model of the sub-atomic components of the atom she 'assigned' (i.e., pre-consciously interpreted them to have) them certain ontological qualities (such as stability, permanence) which made sense to her at the time, but which did not capture the way scientists understand these entities. This assumption of the nature of the neutron acted as a grounded learning impediment, because when she was later taught about radioactivity it did not make sense in terms of her prior learning.

Too crazy to remember?

In a later interview, Amy was able to tell me that the neutron is made up of other stuff, and it decays to give an electron and, she thought, a proton – although (she told me) that was only a guess.

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Sharing the same shell and electron makes them more joined together like one

Keith S. Taber

Umar was a participant in the Understanding Chemical Bonding project. When I spoke to him in the first term of his advanced level chemistry course he identified figure 2 (below) as representing a hydrogen molecule, with covalent bonding.

Sharing the same shell and electron makes them more joined together like one

Umar was a participant in the Understanding Chemical Bonding Project. When I spoke to him in the first term of his advanced level chemistry course he identified figure 2 (below) as representing a hydrogen molecule, with covalent bonding.

Figure 2 (Focal image – Understanding Chemical Bonding project)

Umar suggested that covalent bonding is when atoms share electrons to combine into one whole thing. That discussion took place early in the interview, before we then discussed a whole range of other images. Near the very end of the interview I returned to ask about figure 2 again.

Interviewer: And number 2 was what kind of bond?
Umar: Covalent.
I: Now, what holds the molecule together in number 2?
U: The two electrons – shared.
I: And how does that hold them together?
U: 'cause they're sharing the same – shell and electron.
I: And why does that hold them together?
U: Makes them more, together like, makes them more like joined together like one.

After we had first discussed what this image was meant to represent early in the interview, Umar discussed a wide range of other images, and in the context of some of these he discussed bonding in terms of forces and electrical charge. As he had not mentioned such notions in the context of figure 2, even after using the ideas elsewhere, I sought to see if he recognised that forces were acting in the hydrogen molecule.

I: I see. Is there any force there holding them together?
U: It's, erm could be the charges of the electrons and the charge of the nucleus.
I: Would the nucleus have some sort of interaction with the electrons – some sort of attraction or repulsion?
U: Yeah.
I: Would it be attraction or repulsion?
U: Erm, attraction.
I: So which electron does this nucleus attract.
U: Erm, it attracts both of them, and the other one attracts both of them because they are both, like, opposite charges. So that's why they are like, around there. It might be like they move around. Around that part.
I: So they might actually move about?
U: Yeah.
I: I: But you think the two nuclei attract the two electrons?
U: Yeah.
I: Do the two electrons attract the two nuclei?
(Pause, c.3s)
U: Yeah, think so, the – yeah.
I: Yeah? Do the two electrons attract each other?
U: No, they repel.
I: Do the two nuclei attract each other?
U: No they repel.

So it seemed that Umar understood the forces acting in the covalent molecule but that these ideas were not readily cued in that context even though he readily used the idea of forces between charges to explain other kinds of chemical bonding. In the context of covalent bonding however, the notion of the bond as electron 'sharing' was cued instead. Arguably the notion of the covalent bond as sharing of electrons acted as a grounded learning impediment perhaps blocking him bringing to mind alternative ways of thinking about the bond. This could be seen as an example of weak anthropomorphism: the idea that the electrons were 'shared' stood in place of a more scientific explanation of the bonding process.

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Covalent bonding is when atoms share electrons to combine into one whole thing

Keith S. Taber

UCB Figure 2 (for interview-about-instances technique)

Can you tell me what you think that's meant to represent?
Er, two hy-, a hydrogen molecule, 'cause it's like they've got one electron, in the only one shell, and they're joined together, a covalent bonding, and they're sharing it.
So what is a covalent bond exactly?
When they share electrons.
When you share electrons?
Yeah.

So when Umar thought of covalent bonding he seemed to primarily associate this with the notion of 'sharing' of electrons. The idea that atoms can 'share' anything could be considered an example of anthropomorphism, but this is a common metaphor that is widely used in discussing bonding.

The 'sharing' notion is however little more than a descriptive label, and has limited explanatory power. Acceptable explanations of the bond would draw upon scientific concepts, such as electrical forces, or atomic orbital overlaps allowing the formation of lower energy molecular orbitals. I probed Umar to see how he understood the nature of the covalent bond.

Or do you think they're stuck together?
I think they're quite strong together, covalent is quite a strong bond.
So that will hold them together will it?
Yeah.

Umar certainly saw the bond as a strong linkage of some kind, but so far my questions had not revealed how he understood the bond to hold the molecule together.

Well how does it do that?
It's like, they're joined together, 'cause first of all they just had two atoms with one electron each, and now they're sharing two electrons between them. So it's quite strong.
Oh, why's that?
Because the the the actual, when they share them they're like combined into like one sort of whole thing, instead of two separate atoms.
Right, so the, so the bond, which is the sharing of two electrons, that holds them together,
Yeah.
to make one thing, which we've called a molecule.
Yeah.

So at this point in Umar's course he seemed to conceptualise the covalent bonding as electron sharing and saw the action of sharing to inherently hold the molecule together, and seemed to be satisfied with that as an explanation for the bond. This discussion took place early in the interview, before we then discussed a whole range of other images. Near the very end of the interview I returned to ask about figure 2 again (see Sharing the same shell and electron makes them more joined together like one)*.

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Bert's understanding of the reciprocal nature of forces

The plus sign shows Na+ has an extra electron in its outer shell; the minus sign shows Cl– has seven electrons in its outer shell so its minus an electron

Calcium and oxygen would not need to bond, they would just combine, joining on to make up full shells

Bert Suggests Chemical Bonding Evolved

Forgetting the source?

Some crazy thing about a neutron turning into a proton or something

Too crazy to remember?

Sharing the same shell and electron makes them more joined together like one

The plus sign shows Na⁺ has an extra electron in its outer shell; the minus sign shows Cl^– has seven electrons in its outer shell so its minus an electron