State that a structural formula is an unambiguous description of the way the atoms in a molecule are arranged, including $mathrm{CH}_2=mathrm{CH}_2$, $mathrm{CH}_3 mathrm{CH}_2 mathrm{OH}, mathrm{CH}_3 mathrm{COOCH}_3$

What is a Structural Formula?

A structural formula is like a blueprint that shows exactly how every atom is connected in a molecule. It tells you which atoms are bonded, the type of bonds (single, double, triple), and the arrangement of atoms in space. Think of it as the road map of a city – it shows all the streets (bonds) and buildings (atoms) so you can navigate from one point to another without guessing. 🚗🏙️

Examples of Structural Formulae

• Alkene (ethylene): \$ \mathrm{CH2=CH2} \$ – two carbon atoms double‑bonded, each with two hydrogens.
• Alcohol (ethanol): \$ \mathrm{CH3CH2OH} \$ – a chain of two carbons with an –OH group on the second carbon.
• Ester (methyl acetate): \$ \mathrm{CH3COOCH3} \$ – a carbonyl group (C=O) linked to an –O–CH₃ group.

Functional Groups – Quick Reference

Terminology to Know

1. Atom – the basic building block (C, H, O, N, etc.).
2. Bond – connection between two atoms (single, double, triple).
3. Functional Group – a specific arrangement of atoms that gives a molecule its characteristic properties.
4. Isomer – compounds with the same molecular formula but different structural arrangements.
5. Chirality – a molecule that cannot be superimposed on its mirror image (like left and right hands).

Exam Tips 📚

• Always label every atom in a structural formula – missing a hydrogen can change the answer.
• Show bond order clearly: use "=" for double bonds and "≡" for triple bonds.
• When drawing a new molecule, start with the backbone (main chain) before adding side groups.
• Practice naming by identifying the longest chain and the highest‑priority functional group first.
• Use colour coding in your notes: e.g., blue for carbons, red for heteroatoms, green for functional groups.