In this qualitative study, the researchers explored the ways in which 21st-century skills (specifically communication and critical thinking) are enhanced by Grade 10 beginner Physical Sciences teachers while teaching Particulate Nature of Matter (PNM) through the implementation of problem-based learning (PBL). The study was conducted in one of the four educational districts of the North West province, South Africa. The district was selected due to its geographical proximity and accessibility to the researchers. Two participants were purposively selected from two rural government secondary schools. Research instruments for the study comprised an open-ended questionnaire and a reflective portfolio. The data were analyzed manually using Saldaña's model and Smith et al.'s assessment rubric. The findings show that PBL enhances communication and critical thinking skills. It is recommended that a teacher professional development (TPD) training program be presented for beginner Physical Sciences teachers which targets the formulation of PBL problems, the promotion of 21st-century skills (communication and critical thinking), and the implementation of PBL in other topics in Chemistry.