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.
Earlier in her interview she had suggested that plus and minus signs represent the charges on neutral atoms when discussing the Na-plus (Na+) and Cl-minus (Cl–) symbols, suggesting an alternative conception of electrical charge in relation to atoms, ions and molecules She gave similar interpretations in the case of K-pus (K+) and F-minus (F–):
Right, okay, so this one here where it's got a K and a plus, what does that represent?
Potassium…An atom that has an extra electron.
Potassium atom, and it's got one extra electron over a full shell
Yeah.
and that's what the plus means, one more electron than it wants?
Yeah.
And what about the F minus?
Represents fluorine which has one, it has an outer shell of seven which has one less electron.
So, for Annie:
K+ referred to the potassium atom (2.8.8.1), not the cation (2.8.8)
and
F– referred to the fluorine atom (2.7), not the fluoride anion (2.8)
Students often present incorrect responses in class (or in interviews with researchers) and sometimes these are simply slips of the tongue or memory, or 'romanced' answer guessed to provide some kind of answer.
When a student repeats the same answer at different times it suggests the response reflects a stable aspect of their underlying 'cognitive structure'. In Annie's case she not only provided repeated answers with the same examples, bit was consistent in the way she interpreted plus and minus symbols across a range of different examples, suggested this was a stable aspect of her thinking.
