Curved arrows show the flow of electron pairs in a reaction mechanism. Rules: 1. They always go from an area of high electron density (negatively charged) to an area of low electron density (positively charged). 2. The head of the arrow is pointing to a positively charged atom. 3. The end of the arrow is coming from a set of electrons, like a bond or a lone pair of electrons. 4. Never show the movement of atoms; they're assumed to form bonds based on where you move these electrons. View the slides for some examples of electron pushing.