The idea of atoms is the single key idea that separates chemistry from the alchemy. Atoms provide a non-magical explanation for the central tenants of chemistry from stoichiometry (the masses of compounds in a reaction are proportional to one another because of the ratio of atoms) to intermolecular forces (the properties of atoms within molecules explain boiling and melting point of compounds) to kinetics (the rate and energy of collisions between atoms controls the speed of reactions).
Given the importance of atoms it is odd that we do not focus on them more. We tend to focus more on number crunching and symbolic representations (think reaction equations) than on atoms. That, however, is changing as the research on misconceptions and multiple representations has forced us think harder about what it means to educate young chemists. Students need to learn to represent atoms, ions and molecules to gain a deeper and more expert-like understanding of chemical phenomena.
In 2014 I wrote an article for the Journal of Chemical Education’s special issue on the new AP Chemistry curriculum. That curriculum has a strong emphasis on particles – and in particular particle diagrams – not seen in more traditional curricula. I felt like that aspect of the curriculum was going to be tough for teachers to know how to approach and so wrote the article to fill that need.
My article about particle representations in the Journal of Chemical Education is now available as an open access article. It is free to read it online and distribute in any way. The only thing I ask is that you attribute the work to me when you share it. Otherwise I hope you will find it interesting and helpful to your practice of teaching chemistry.