Atom and molecule: upper secondary school French students ...

A. Cokelez and A. Dumon 126
of four electron pairs around the symbol of the element (and this accounts for 13% and 10%),
followed by the showing of the six outside electrons (10% and 7%).
The use of the atomic composition model, and more particularly that of ‘neutral atom’,
reaches a maximum when students enter grade 11, whereas it accounts for a majority of
representations in the textbooks of grade 9. It seems therefore, that its adoption, however low,
is favoured in the teaching of the electronic structure and nucleus composition. A low
percentage in the choice of electron cloud model can be seen among different grades,
although it is the description that textbooks authors as well as curricula developers favour.
Thus, as Harrison and Treagust (1996, 2000) showed in their work, such a model is not easily
grasped by students.
Another interesting observation is that the use of the solar system model of atom
increases from grade 10 to grade 12. Yet this model is not often used in textbooks, as it
appears only in documents with historical contents. Moreover, although Official Instructions
forbid the representation of the solar system model in shells in 2D, some students (8% in
grade 10, 10% in grade 11 and 11% in grade 12) choose this diagram. Is that a consequence
of school knowledge or is it the students' own conception to represent electronic shells?
Finally, as far as other representations are concerned, they can mainly be explained by
the confusion between atom and molecule. One can regret that 5% of grade 12 students still
remain at this level!
Description of the atom
A vast majority of students cannot produce a minimum level of description of the concept
of atom required at the end of each grade. The differences observed between the three grades
prove that if the teaching in grade 10 brings along a clearly positive evolution, the concept is
not well absorbed. Indeed, whenever it is not the subject of teaching (i.e. in grade 11), its
minimum characteristics appear to have been forgotten by the following year.
The minimum level judged acceptable at the end of grade 9, (L1) is only reached by 21%
of grade 10 students, 47% of grade 11 students and down to 25% of students at the beginning
of grade 12. As far as the minimal level acceptable at grade10 is concerned (L3), only 35% of
grade 11 students and 15% of grade 12 students reach it. (The levels of description are
described on p. 124.)
Figure 4: Comparison of the levels of description of the atom at different
grades
Answers
(%/R)
80
70
60
50
40
30
20
10
0
L.0 L.1 L.2 L.3 L.4 L.5 L.6
Grade 10 79 12 4 2 3 0 0
Grade 11 53 11 1 7 13 9 6
Grade 12 75 9 1 3 6 3 3
From the diagrams and keywords, we have tried to discover what competences expected
at the end of grade 10 appear in the students’ answers at grades 11 and 12:
Chemistry Education Research and Practice, 2005, 6 (3), 119-135
This journal is © The Royal Society of Chemistry