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Similar-looking arrows asserting opposite things, and confused constantly.
Count the shafts and look at the heads. Equilibrium is two separate half-headed arrows pointing opposite ways: two real species interconverting, both present. Resonance is one shaft with a full head at each end: one species that neither drawing captures. Reading resonance as equilibrium claims two substances exist where there is only one.
Both are double arrows between structures and they mean opposite things.
| Equilibrium arrow | Resonance arrow | |
|---|---|---|
| What exists | Both species, simultaneously | Neither, as drawn — one real hybrid |
| Shafts | Two, stacked | One |
| Arrowheads | Half-headed barbs | Full heads at both ends |
| Can the ratio shift? | Yes — that is what equilibrium means | No — there is nothing to shift |
| Relationship (from Symbolwise's records) | Commonly confused with Resonance arrow — Both are double arrows between structures and they mean opposite things. | Commonly confused with Equilibrium arrow — Opposite assertions made by similar-looking arrows. |
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol denotes in ordinary scientific practice and for which fields reuse it, never for a claim that any body assigns the letter its meaning.
Wikipedia · retrieved 2026-08-01
Tertiary reference. Used for what a symbol denotes in ordinary scientific practice and for which fields reuse it, never for a claim that any body assigns the letter its meaning.
The logical arrow has a doubled shaft and joins two statements that hold in exactly the same circumstances. The chemical one has a single shaft, joins two structural formulae, and means something stranger: neither structure exists, and the real molecule is a single thing no drawing captures.
Look for the horizontal line. Fire is a plain upward triangle; air is the same triangle with a bar drawn across its upper part. Dropping the bar is the commonest error in reproductions of the element set, and it turns air into fire.
The same rule as fire and air, inverted. Water is a plain downward triangle; earth is the same triangle with a bar across its lower part. The four element signs are one designed set: two point up, two point down, and within each pair the bar is the only difference.
Alpha is a Greek letter and stands for a quantity — an angle, a coefficient, a significance level. The proportionality sign is an operator and stands between two quantities to say they keep a constant ratio. The drawings differ in that the proportionality sign's right-hand stroke runs out in an open curve rather than closing into the letter's tail.