This study investigated how modeling in chemistry affect second language learners’ descriptions of polymeric concepts. The aim was to investigate how chemistry discussions mediated by representations, contribute to second language students’ development in the language of chemistry. The study took place in three multilingual upper secondary classes. Participating students were (n = 16) second language learners and (n = 14) first language learners. There were in total eight different first languages represented. Data comprised polymeric concept descriptions, audio recordings, and photos taken during modeling. The concept descriptions were analyzed by an inductive content analysis which was then used for a deductive analysis of the modeling-activity. The results show that 65% of second language learners concept descriptions showed an increased clarity, and 45% showed increased use of chemical concepts after the modeling-activity. This study highlights how students in a multilingual context develop their language of chemistry by discussing chemistry scaffolded by representations. The results show that second language learners in a multilingual context benefited from the modeling-activity. As such, the study acknowledges that modeling contexts can be used in teacher education, both in-service and pre-service, to highlight the importance of the role of representations when teaching in the multilingual context.