Splitting follows the n + 1 rule: a proton with n neighboring protons — equivalent to each other, but non-equivalent to the observed proton — is split into n + 1 peaks. When neighboring protons belong to more than one non-equivalent set, the result is a more complex multiplet (e.g., a doublet of doublets), not a simple n + 1 pattern.

Neighboring Protons (n)	Multiplicity	Peaks
0	Singlet	1
1	Doublet	2
2	Triplet	3
3	Quartet	4
4	Quintet	5

Representative Coupling Constants (J, in Hz)

Relationship	Typical J (Hz)
Vicinal, freely rotating sp³–sp³ (³J)	6–8
Vicinal, alkene, cis	6–12
Vicinal, alkene, trans	12–18
Geminal, alkene (same carbon)	0–3
Aromatic, ortho	7–10
Aromatic, meta	1–3
Aromatic, para	0–1

Why trans coupling exceeds cis coupling on an alkene: this is a geometric/orbital overlap effect, not something to derive from first principles at this stage — but it is worth recognizing as a diagnostic tool: a large vicinal J (12–18 Hz) across a double bond indicates a trans (E) relationship, while a smaller one (6–12 Hz) indicates cis (Z), directly connecting an NMR spectrum to the E/Z nomenclature in Appendix E.

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