curly arrows 

https://doi.org/10.1351/goldbook.08160
Symbols for depicting the flow of electrons in a chemical reaction or to generate additional resonance forms.

Note 1: The tail of the curly arrow shows where an electron pair originates, and the head of the curly arrow shows where the electron pair goes.

Note 2: Single-headed curly arrows are used to depict the flow of unpaired electrons.

Examples:

Source:
PAC, 2022, 94, 353. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 2021)) on page 395 [Terms] [Paper]
Citation: 'curly arrows' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.08160 RIS BibTex EndNote
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