Atom and molecule: upper secondary school French students ...
Atom and molecule: upper secondary school French students ...
Atom and molecule: upper secondary school French students ...
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A. Cokelez <strong>and</strong> A. Dumon 128<br />
The analysis of the <strong>students</strong>' answers leads to various kinds of diagrams <strong>and</strong> levels of<br />
description, as happened for the atom. Key words appearing in the descriptions are presented<br />
in Table 2 (Appendix).<br />
Different kinds of diagram:<br />
D.0: Erroneous answer or no answer.<br />
D.1: Space-filling model.<br />
D.2: Ball <strong>and</strong> stick model.<br />
D.3: Lewis structural formula model.<br />
D.4: Lewis formula model.<br />
Examples of such diagrams are given in figure 5.<br />
Figure 5: examples of diagrams of the water <strong>molecule</strong><br />
2<br />
1<br />
Space-filling model<br />
Ball <strong>and</strong> stick model<br />
Lewis structural formula<br />
Lewis formula<br />
Levels of description:<br />
L.0: Erroneous description or no answer.<br />
L.1: Water <strong>molecule</strong> is made of two atoms of hydrogen <strong>and</strong> one atom of oxygen.<br />
L.2: Water <strong>molecule</strong> is made of two atoms of hydrogen linked to one atom of oxygen.<br />
L.3: Water <strong>molecule</strong> is made of two atoms of hydrogen linked to one atom of oxygen by a<br />
covalent bond (or simple bond).<br />
L.4: Water <strong>molecule</strong> is made of two atoms of hydrogen linked to one atom of oxygen by a<br />
covalent bond composed of two electrons (or linked electron pair).<br />
L.5: Water <strong>molecule</strong> is made of two atoms of hydrogen linked to one atom of oxygen by a<br />
covalent bond. Each atom contributes one electron to make the bond.<br />
Level 1 is required at the end of grade 9, level 3 is the minimum judged acceptable at the<br />
end of grade 10 <strong>and</strong> level 5 corresponds to the level of formulation in that class.<br />
Analysis of results<br />
Diagram of the water <strong>molecule</strong><br />
The percentage of total answers to this second question is higher than that to the<br />
questions on the atom. Students seem more familiar with the water <strong>molecule</strong> than with the<br />
atom. Yet it is puzzling to note that the difference between these two percentages is higher<br />
for grade 12 <strong>students</strong> (-16%) than for grade 10 (-13%) although the description of water<br />
<strong>molecule</strong> is taught in grade 10 <strong>and</strong> 11 curricula.<br />
As Pereira <strong>and</strong> Pestana (1991) <strong>and</strong> Harrison <strong>and</strong> Treagust (1996) showed, Figure 6 shows<br />
an evolution in the drawing of diagrams along Upper Secondary School. When entering grade<br />
10, the majority of <strong>students</strong> (68%) choose the model that was introduced at Lower Secondary<br />
level: the space-filling model. In grades 11 <strong>and</strong> 12, they mainly rely on Lewis formula model,<br />
which was studied in grade 10 (37%). In grade10, ball <strong>and</strong> stick models of <strong>molecule</strong> are also<br />
Chemistry Education Research <strong>and</strong> Practice, 2005, 6 (3), 119-135<br />
This journal is © The Royal Society of Chemistry
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