Students investigate how atomic structure explains the identity and behavior of main-group elements by building and revising a model of an element from Period 2 or 3. They use periodic table evidence to show atomic number, average atomic mass, common isotopes, protons, neutrons, electrons, and valence shells, then connect outer electrons to reactivity, ion formation, bonding, and simple reactions. Across the project, students refine their thinking through partner walks, sticky-note reflections, and gallery walk feedback before presenting an atom model checkpoint and a final reaction explanation. The work culminates in a public showcase where students use their model, info sheet, and reaction display to explain how structure predicts chemical behavior.

Students will identify main-group elements by atomic number, symbol, and average atomic mass and use that information to build accurate models showing protons, neutrons, electrons, nucleus structure, and the most common isotope for a Period 2 or Period 3 element. They will determine valence electrons and outer-shell patterns and use those patterns to explain identity, mass, charge, likely ion formation, bonding behavior, and relative reactivity. Students will use evidence from the periodic table to predict and explain simple reactions, including whether an element stays neutral, forms an ion, or reacts with oxygen or another main-group element. They will strengthen their explanations and models through peer critique, sticky-note reflection, revision, and public presentation during the final showcase.

Students will create an annotated atom model for an assigned main-group element in Period 2 or 3, along with an element info sheet that includes atomic number, symbol, average atomic mass, most common isotope, valence electrons, and likely ion formation or reactivity. By the end of week 3, they will present a labeled model that explains protons, neutrons, electrons, charge, and outer shell patterns using periodic table evidence. In weeks 4 and 5, they will add a reaction display that shows how their element forms an ion, bonds, or reacts with oxygen or another main-group element, supported by a written or visual explanation. The final product is an Element Expo or Periodic Table Museum exhibit that combines the revised atom model, sticky-note reflections, info sheet, and reaction scenario for an audience.

Open with a Reaction Preview Lab in which students rotate through 3–4 short, safe demonstrations that show different levels of reactivity and stability among main-group elements or compounds, then record what they notice about patterns in outcomes. Reveal that each student or pair will later become the “expert” on one Period 2 or 3 element by building a model, creating an info sheet, and explaining how its outer electrons predict ion formation, bonding, and reactions. End with a quick element assignment and a brief table talk in which students use the periodic table to make an initial claim about their element’s mass, charge, and likely reactivity. Close by collecting their first predictions on a class display that can be revisited during critique, reflection, and the final showcase.

Host an Element Expo Showcase where students present at table stations with their atom model, info sheet, and a reaction display showing whether their Period 2 or 3 element forms an ion or bonds with another main-group element. Invite another chemistry class, families, or school staff to tour a Periodic Table Museum, ask questions, and use a simple feedback form to check for accurate explanations of mass, charge, valence electrons, isotopes, and reactivity. Students should act as exhibit guides, using periodic table evidence to explain how their element’s structure predicts its behavior in reactions with oxygen or other elements. Include the sticky-note reflections from week 3 and revised model notes from peer critique so visitors can see how each project improved over time.