Symbolic expressions are essential resources for producing knowledge, yet they are a source of learning difficulties in chemistry education. This study aims to employ social semiotics to analyse the symbolic representation of chemistry from two complementary perspectives, referred to here as contextual (i.e., historical) and functional. First, the contextual account demonstrates that symbolism was introduced to represent compounds according to their elemental composition, to quantify chemistry, and to explain reactivity. Further to this, the functional analysis shows that symbolic expressions entail a range of unique grammatical resources to create specialised forms of knowledge, which cannot be made by natural language alone. It is found that historically the symbolic representation was not originally directly related to the submicroscopic domain, nor did it develop sufficient means to offer particulate explanations, although an indirect link could be set up between Berzelian formulae and the submicroscopic theoretical models. It is also found that understanding the quantitative aspects is a necessary but not sufficient condition for effective engagement with the symbolic representation of chemistry. Finally the present study discusses the pedagogic implications stemming from the social semiotic account of chemical symbolism.