In my chemistry study material a set of rules to draw resonance structures are given. They are: (1) Only electrons move. The nuclei of the atoms never move. (2) The only electrons that can move are pi electrons (electrons in pi bonds) and lone-pair electrons. (3) The total number of electrons in the molecule does not change, and neither does the number of paired and unpaired electrons. The electrons can be moved in one of the following ways: (a) Move pi electrons toward a positive charge or towards a pi bond. (b) Move lone-pair electrons toward a pi bond. (c) Move a single non-bonding electron toward a pi bond. As an illustration of the second part of point (a)- move pi electrons towards a pi bond, this picture is given: https://i.stack.imgur.com/D98F1.jpg In the first and second examples pi electrons are moving towards sigma bond and not pi bonds. Right? Then how does this support the first rule that "Move pi electrons...towards a pi bond."? Where am i going wrong? As an illustration of point (b) this image has been given: https://i.stack.imgur.com/5a3jj.jpg In the first example, (i) Why are electrons moving towards oxygen from the pi bond? (ii) Why are electrons moving from the lone pair above nitrogen towards the sigma bond? According to the rules electrons should move from lone pair towards pi bond? In other examples also the same thing is happening. Where am i going wrong exactly? Please help.