In this video, you'll learn to draw the transition state of a step in a reaction, given the starting materials and products of that step. The transition state is the point in the reaction when the bonds are breaking and forming. The transition state corresponds to the highest energy point between starting materials and products of a given step. Bonds can be more or less fully formed, and the extent of bond formation and breakage depends on the energy profile of the reaction. In this example, the mechanism and electron pushing arrows have been drawn for us. Our goal here is to represent the transition state structure. What do the molecules look like at that point? We first draw all the components that do not change between the starting materials and products. It is not necessary to show the non-bonding electrons or the hydrogen atoms that are not directly involved in the reaction. Now draw dashed lines for any bond that break and form during the reaction. These represent partial bonds. For example, the left most curved arrow indicates that the carbon oxygen bond is breaking, so we draw a partial sigma bond in the transition state. The right most curved arrow indicates that a carbon-nitrogen pi bond is forming, so we draw a partial pi bond in the transition state. And delta negative and delta positive symbols, wherever there is a negative or positive charge in one of the structures. This represents a build-up of charge in the transition state. For example, the oxygen atom is positive in the starting material and neutral in the product. In the transition state, it has only a partial positive charge as it begins to accept electron density from a carbon-oxygen bond. In close the whole structure in square brackets. Add a transition state symbol, a double dagger. Finally, put the overall charge beside the transition state symbol. What is the overall charge for this transition state? The overall charge here is positive one. The geometry or confirmation of the transition state is also very important. For example, six-membered ring transition states often have chair confirmations. Because there are so many different variables to consider, the geometry is something you will study in your courses as you learn about each reaction. So that's it. In this video, you learn to draw the transition state structure of a mechanistic step, given the starting materials and products. It's important to depict the breaking and forming bonds with dashed lines. Show the partial charges. In close the structure in square brackets, draw the transition state symbol, and include the overall charge.