Pupils’ representations of models of water

Different representations of models of water based on the particulate nature of matter are included in Portuguese chemistry syllabuses at various levels. The pencil‐and‐paper question ‘Represent water in its three states using a model’ was given to 227 pupils (13‐18 years old) from 8th to 12th grades. The findings show that: the dominant model used was of the space‐filling type; the movement of particles was indicated by a minority of pupils; an increase in the size of the model used and of interatomic bonds was shown in the representations of a liquid and a gas as compared with those of a solid; bond angles were usually incorrectly represented; the molecular spacings in a liquid and a gas, in comparison with those in a solid, were, respectively, over‐ and under‐estimated. Some educational implications of these findings are discussed.