Students will launch the atom investigation by observing reaction patterns, generating evidence-based questions about atomic structure and reactivity, and beginning to use periodic table data to identify assigned main-group elements and plan what evidence they will need for their models.

Students will refine an investigable claim about their assigned Period 2 or 3 element, gather and analyze periodic table evidence, choose a defensible isotope, and produce a peer-checkable hypothesis and model-building method that prepares them for atom construction in the next phase.

Students will build and revise a checkpoint-ready atom model and evidence record for an assigned Period 2 or 3 main-group element by using periodic table data, isotope reasoning, and peer critique to verify identity, structure, and outer electron patterns.

Students will analyze how their assigned Period 2 or 3 element is likely to behave in reactions by connecting atom-model evidence, valence electron patterns, ion formation, and periodic trends. They will test the strength of their claims through structured peer critique, revise their explanations when evidence conflicts, and prepare a concise evidence-based reaction explanation for the next phase’s public exhibition.

Students will present their final atom investigation products to an authentic audience, defend claims about identity and reactivity with periodic table evidence, respond to questions and critique, and complete a concise evidence-based reflection on how their model and explanation changed through revision.