SHS2 Chemistry · Semester 2 Week 9: Bonding

Lesson notes

Learning Objectives

Indicator: 2.2.2.LI.1 - Predict the shape and bond angles for species and distinguish between sigma and pi bonds.

By the end of the lesson, learners can:

Predict the shape and bond angles of molecules and ions with 4, 3, and 2 negative charge centres on the central atom using the VSEPR theory.
Determine whether a molecule is polar or non-polar based on its molecular shape and the polarity of its individual bonds.
Distinguish between sigma (σ) and pi (π) bonds in terms of how atomic orbitals overlap.
Construct simple molecular models to verify predicted shapes of selected molecules.
Use electronegativity values to predict the relative polarity of bonds within a molecule.

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Curriculum details

Strand: Systematic Chemistry of the Elements (Strand 2)
Sub-strand: Bonding (2.2)
Content standard: 2.2.2.CS.1 - Demonstrate knowledge and understanding of the role of modelling, evidence and theory in explaining the structure, bonding as well as properties of molecular compounds 2.2.2.LO.1 Describe the structure, chemical bonding and properties of molecular compounds.
Indicator: 2.2.2.LI.1 - Predict the shape and bond angles for species and distinguish between sigma and pi bonds.
Suggested placement: Semester 2, Week 9 (Week 29 of the year)
Our suggestion, laid out in curriculum order across three terms of twelve weeks. NaCCA does not fix the week, so follow your school's scheme of learning.
Curriculum reference: NaCCA curriculum document, p. 81

Exemplars (from the NaCCA curriculum)

Collaborative Learning Approach:
- Use electronegativity values to predict the relative polarity of bonds.
- Predict the shape and bond angles for species with 4, 3, and 2 negative charge centres on the central atom using the Valence shell electron pair repulsion (VSEPR) theory.
- Predict whether or not a molecule is polar from its molecular shape and bond polarities
Talk for Learning:
- Discuss in a small mixed-ability group, how orbital overlap of two atoms results in the formation of molecular orbital.
- Describe and distinguish between sigma and pi bonds.
Teaching and Learning Materials:
- * Molecular models * Toothpick * Modelling clay * Ball and stick models
- * Coloured balloon * * Worksheets with orbital diagram * CHARTS Balloons of different colours * * Chart Coloured balloons * molecular
- Thread
- * Periodic table
- Ball and stick models
- containing diagrams of orbitals * Chart of the Lewis dot structures
Assessment (2.2.2.AS.1). The document marks these depth-of-knowledge levels for this indicator: Level 2 Skills of conceptual understanding.