# Learning outcomes

After studying Session 4 you should be able to:

- understand how the concept of valency can account for, and predict the formulas of compounds
- sketch Lewis structures of molecules and ions
- identify situations where and appreciation of dative bonding is required to account for the bonding in certain molecules and ions
- appreciate some molecules are not adequately represented by a single Lewis structure and seem to be a composite of two or more resonance structures.

OpenLearn - Discovering chemistry
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