It all stemmed from a passing comment…

Suzanne Fergus and Barry Ryan are mentoring me for my CERG research project, and have already offered me all sorts of insights and advice. Barry wrote this at the end of a long email containing heaps of other useful advice about the questionnaire I’d designed to test student misconceptions:

Wouldn’t it be interesting to get other teachers to complete the quiz also to see what their conceptual understanding is? Or would that open a can of worms?

So I designed a new questionnaire with the same questions, but designed for adults, rather than students, and I wrote a tentative tweet asking if anyone would mind filling it in for me…

Over 300 educators! And they want answers…

326 responses later, and I’ve got some really interesting (and unexpected) data! I’ll look at it all in more detail in the future. For example, I’m really interested in the confidence aspect to the questions, and I’d like to look at the different backgrounds that respondents have, and how this affects their responses.

But lots of people asked for the answers to the questions themselves, so I’m sharing them here, along with the resources from the RSC that helped me formulate the questions. I’m going to share the answers in three separate posts: ions and ionic bonding (this post), simple covalent properties (next post) and giant metallic/ covalent structures (final post).

As much as anything, sharing this questionnaire with so many people has been a really interesting exercise in question design. The final post on metallic/ covalent bonding will be as much about the questions I wrote themselves as the answers people gave. A few people commented on the premise and wording of these questions, so it’ll be really interesting to dissect that a little.

So who filled it in?

326 people started the questionnaire and 317 completed it. They were mostly teachers, and most respondents have a Science degree.

Screen Shot 2019-02-02 at 19.11.08

Screen Shot 2019-02-02 at 19.11.21

Question 1 – the answers

Screen Shot 2019-02-02 at 19.12.40

The answer is B, and 79% of people got this question correct. 

Screen Shot 2019-02-02 at 19.13.07

The question comes directly from this resource from the RSC. (I added the “don’t know” option because I didn’t want any false positives/ negatives from guessed answers).

Screen Shot 2019-02-02 at 22.23.18

The RSC answer sheet explains why this statement is false (NB: See footnote):

  • In the diagram a chloride ion is attracted to one sodium ion by a bond and is attracted to up to three other sodium ions just by forces.
  • FALSE: In the diagram each chloride ion is attracted to up to four sodium ions by a bond that is an electrostatic force. (There would also be a fifth sodium ion above the chlorine ion and one more below – but these are not shown in the diagram.)

Question 2 – the answers

Screen Shot 2019-02-02 at 19.13.28

The answer is D, and 78% of people got this question correct. This was a question I wrote myself, to try and uncover the confusion students often feel about why molten/aqueous ionic compounds conduct electricity.

Screen Shot 2019-02-02 at 19.13.50

But this question is also about the very specific language and vocabulary that students need to be familiar with when they talk about structure, bonding and properties. Even at A level, students often need to be reminded that molecules are a specific type of species, as reflected by this question, which is part of the RSC misconceptions quiz:

  • There are no molecules shown in the diagram.
  • TRUE: A molecule comprises a group atoms strongly bound together, and only weakly bonded (if at all) to other molecules. In sodium chloride each ion is strongly bonded to each of its six nearest neighbours.

Question 6 – the answers

Screen Shot 2019-02-02 at 19.14.16

The correct answer was A. And it was only A, although I gave the option for people to choose as many answers as they wanted to, to try and increase the chance of picking up on respondents’ misconceptions. 80% of people chose the correct answer. But 20% of people chose answer D, which revolves around the misconception tested in question 1.

Screen Shot 2019-02-02 at 19.14.46

The options are taken directly from the RSC misconceptions quiz questions below:

  • A positive ion can be bonded to any neighbouring negative ion, if it is close enough.
  • TRUE. The bond is just the attraction between the oppositely charged ions. If the ions are close together this force will be a strong bond.
  • It is not possible to know where the ionic bonds are, unless you know which chloride ions accepted electrons from which sodium ions.
  • FALSE: as the bonding is just the attraction between ions, there will be a bond between any adjacent oppositely charged ions.
  • A chloride ion is only bonded to the sodium ion it accepted an electron from.
  • FALSE: each negative chloride ion is bonded to each of the neighbouring positive sodium counter-ions. It is irrelevant how the ions came to be charged.
  • A chlorine atom can only form one strong ionic bond, because it can only accept one more electron into its outer shell.
  • FALSE: a chloride ion can strongly bond to as many sodium ions as can effectively pack around it in the regular crystal lattice. In NaCl there will be six sodium ions strongly bonded to each chloride ion.

Question 7 – the answers

Screen Shot 2019-02-02 at 19.15.11

The answer is D only, despite respondents being able to choose as many answers as they wanted. 80% of people chose this answer, but C was chosen by 18% of people. The options were again taken directly from the RSC misconceptions quiz questions.

Screen Shot 2019-02-02 at 19.15.33

Question 9 – answers

Screen Shot 2019-02-02 at 19.15.55

The answer is F, and this answer was chosen by 77% of people. This was written to test similar concepts and language to question 2.

Screen Shot 2019-02-02 at 19.16.17

Question design – it’s tougher than it looks!

I had some really interesting comments relating to these questions, including:

  • Magnesium and chloride ions, or magnesium ions and chloride ions?

(good point! My wording actually implies that there are no longer magnesium ions)

  • In introductory chemistry (class to take if students don’t have chemistry from high school or need a class as a non-major. at the university level) we never talk beyond that a cation and anion make a singular bond. So we never talk about how ions interact with the other ones around it in a lattice. Maybe it’s time to change that. We spend a lot more time on IMF.
  • I had never thought about the difference shown in the number of chlorides around each sodium ion between ball and stick (6) models and space saving models (4) as I rarely teach them a number at GCSE it’s not been a problem but interesting. Thank you
  • I got A at O level chemistry and C at A level and realise despite this I am really muddled about bonding. I don’t think we did lattices then. (A level 1981) it’s not relatively new though is it?

And there were some other really interesting general comments, which gave me pause for thought, including:

  • I worry that the wording of some questions will lead to errors in answering.
  • One or two questions had slightly ambiguous answers
  • Some of the questions need to have clearer wording as they can be interpreted in a different way. You also have some answers that are the same.

This shows how important it is to ask others to review your questions… especially over 300 of them!

And one comment about the question design process itself was really helpful:

  • Nearly got caught out by the last question until I realised it was asking for an incorrect statement. It was interesting how carefully some questions needed reading e.g. having to think about bonds/forces and also having to make sure whether they were referring to ions/atoms/molecules. My hunch is that wrong answers might come in two categories: misconceptions about bonding (e.g. thinking that Na has one ionic bond with Cl) and a (perhaps WM capacity issue) where the conception is correct but then reference to different types of particles has been overlooked. The first element reminds me of Sadler & Sonnertbut I think there is this additional difficulty with these questions. Interesting. Thanks.

Definitely going to look at this paper in more detail. Thanks for the link!

Other comments

Kelly Draper has built a Kahoot quiz with these questions in, which you can access here.

A couple of people commented on the likelihood of teachers holding these misconceptions themselves:

  • I would be really interested in reaching your research based on this survey. Many students start A level holding misconceptions about this material and I’ve always suspected some of their teachers do as well.
  • Although this quiz contained examples of many misconceptions, if teachers don’t get most of the answers right, I would be concerned for qulity of future chemistry teaching.

(If I’m honest, I held a few of these myself before I really started to look into this and read around the resources and research on this. But it’s made me realise how important it is to increase subject knowledge and pedagogical content knowledge).

What was lovely about this was how many people seemed to enjoy doing the quiz.

  • Some interesting questions. It’s before 9am on a Sunday morning and I’m now thinking about bonding before drinking coffee….
  • Brilliant questions – really make you think!
  • I questioned myself a lot!
  • Excellent diagnostic Questions
  • Though provoking, Niki! I hope I got them all right…
  • I could see some questions were very similar and this then challenged how sure I felt about my answers. Good questions which really highlighted how much chemistry I have forgotten in the last 30+ years!
  • I know less than I thought I did and I’m not confident about what I do and don’t know!!
  • That was pretty taxing for a friday afternoon
  • Grt questions. Please send answers!

Footnote 1: What I’ve now realised is that my diagram for question 1 is incorrect for the wording! It comes from the RSC resource, which uses this diagram, whereas I’ve used a 3D lattice diagram.

Screen Shot 2019-02-02 at 21.48.27

But the principle still stands: sodium ions don’t bond with a single chloride ion, and there’s no distinction between the forces of attraction in each direction.