Two rightward arrows asserting that one thing follows from another, in unrelated fields.
Look at the shaft and at what surrounds it. Logical implication is drawn with a doubled shaft and sits between statements; a reaction arrow has a single shaft and sits between chemical formulae, usually with conditions written above and below it. Neither is an equals sign, and both assert direction rather than equality.
Both are rightward arrows asserting that one thing follows from another.
| Implies sign | Reaction arrow | |
|---|---|---|
| What it asserts | If the left holds, so does the right | These reactants become these products |
| Shaft | Doubled | Single |
| What sits either side | Statements | Chemical formulae |
| Anything written on it? | No | Yes — catalyst, temperature, solvent |
| Relationship (from Symbolwise's records) | Commonly confused with Reaction arrow — Both are rightward arrows asserting that one thing follows from another. | Commonly confused with Implies sign — Both are rightward arrows asserting that one thing follows from another, in unrelated fields. |
Wikipedia · retrieved 2026-07-31
Tertiary reference. Used for what the notation means in ordinary mathematical practice and for attribution of its introduction, not for a claim that any body defines it.
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.
Count the arrowheads. A single head means implication: if the left statement holds then so does the right, with no claim in the other direction. Two heads mean equivalence: each statement implies the other, so they hold in exactly the same circumstances. Reading a one-way implication as though it were equivalence is the commonest error made with either symbol.
In logic it asserts that the right-hand statement follows from the left-hand one. In JavaScript the same arrow separates a function's parameters from its body. Both are drawn as two horizontal strokes followed by an angle bracket, and the notations are otherwise unconnected.
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.
The becquerel counts nuclear decays — one per second — and says nothing about harm. The sievert weights absorbed energy by the kind of radiation delivering it, and so estimates biological effect. A becquerel of one isotope and a becquerel of another can carry very different risk, which is exactly why exposure limits and medical doses are stated in sieverts and never in becquerels.