Lesson Plan

• Describe the link between group position and valence‑electron configuration.
• Explain why elements in the same group show similar chemical reactivity.
• Predict trends in ionisation energy, atomic radius and reactivity down a group.
• Apply electronic‑configuration knowledge to write the outer‑shell configuration for given elements.

• Projector and screen
• Colour‑coded periodic‑table poster
• Worksheet with element lists and configuration tables
• Model kits or ball‑and‑stick sets (optional)
• Whiteboard and markers
• Exit‑ticket slips

Begin with a quick “mystery element” demonstration where students guess the group based on a simple reaction. Review that students already know about periods, groups and valence electrons. State that by the end of the lesson they will be able to explain and predict group similarities using electronic configuration.

1. Do‑now (5 min): Write the electronic configuration for Na and Cl; discuss differences.
2. Mini‑lecture (10 min): Review valence‑electron concept and how it repeats down groups.
3. Guided practice (12 min): In pairs, use the periodic‑table poster to fill a table of groups 1, 2, 13, 17, 18 with valence configurations and typical behaviour.
4. Interactive demonstration (8 min): Show reactions of a Group 1 metal and a halogen, linking observed reactivity to their configurations.
5. Concept check (5 min): Quick quiz on which property (ionisation energy, atomic radius) increases or decreases down a group.
6. Application activity (10 min): Students write the outer‑shell configuration for a given element and predict its chemical behaviour.
7. Exit ticket (5 min): One‑sentence summary answering “Why do elements in the same group behave similarly?”

Summarise that identical valence‑electron configurations drive the chemical similarity of group members. Collect exit tickets to assess understanding and assign a short homework: complete a worksheet extending the table to include Groups 3 and 4.