ABSTRACT
The periodic table is a ubiquitous feature of the subject of chemistry, and there is usually at least one representation of the table displayed in any chemistry classroom. A young learner faced with their first instance of a periodic table is likely to think that a teacher is referring to that specific graphic, and indeed if the teacher comments ‘look at the periodic table’, this certainly seems to mean that. Most periodic tables show the elemental symbols of the elements and often the atomic number of each element. The periodic table is a representation of the periodicity of elemental properties. It is a way of summarising a good deal of information, and so a thinking tool in building explanations and predictions. The periodic table is a model because it simplifies the complexity of the nature of the chemical elements. Properties of this kind are sometimes called physical, as opposed to chemical, properties. Density would be another physical property.
