UNIT OVERVIEW

In Term 1, you learned how atoms connect to form chemical bonds. This unit goes further — you will discover how these bonds create different structures, and how structure determines the properties of substances.

In this unit, you will learn:

• What particles different types of substances are made of
• The difference between covalent molecular structures and covalent network structures
• How ionic substances are structured and why they behave as they do
• How to determine molecular formulae from diagrams
• How to write empirical formulae for network structures
• How bonding type affects physical properties like melting point, hardness, and electrical conductivity

By the end, you will understand:

• Why diamond is hard but graphite is soft (both are pure carbon)
• Why salt conducts electricity when melted but not when solid
• Why sugar dissolves in water but doesn't conduct electricity
• Why silicon is used in computer chips

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