1. A condensed formula lists atoms in bonding order with the bonds left unwritten.
CH₃CH₂CH₂CH₃ reads as a four-carbon chain — each carbon and its hydrogens grouped, connected left to right.
2. Parentheses with a subscript collect repeated or branching groups on one atom.
(CH₃)₂CHCH₃ is 2-methylpropane and (CH₃)₄C (neopentane) is a central carbon bearing four methyls.
3. A carbonyl carbon is written inline as CO, so a ketone reads CH₃COCH₃.
The C=O double bond is implied by the CO written between two carbons — CH₃COCH₃ is acetone.
4. Functional-group endings like OH, CHO, and COOH sit at the end of the chain.
CH₃CH₂OH is ethanol and CH₃COOH is acetic acid — the last cluster names the group.
5. Converting condensed ↔ bond-line just means drawing each carbon as a vertex and hiding the H's.
Read the condensed string left to right, place a vertex per carbon, then attach branches shown in parentheses.
6. Summary
Atoms in bonding order · bonds implied · parentheses+subscript = branches · CO = carbonyl · OH/CHO/COOH end groups · convert by drawing one vertex per carbon.
Quiz yourself
Tap a question to reveal the answer — free, no login.
Four carbons in a straight chain — that's butane.
A central carbon carries three CH₃ groups plus a Cl — tert-butyl chloride.
A carboxylic acid group (COOH) — the molecule is acetic acid.
A carbon–oxygen double bond (C=O), the carbonyl of acetone.
Draw this on the whiteboard
Open the OChem Board whiteboard — benzene rings, wedge/dash bonds, and a clickable periodic table built in. No account needed.