You want to start by drawing the NO molecule and O2 molecule. This would be with their bonds showing such as, N=O N=O and O=O as the reactants and O-N=O molecule as the product. There is no loss or destruction of any atoms, you will have the same amount of nitrogens and oxygens as you started with. Breaking bonds requires energy, while forming bonds releases energy. The overall energy change depends on the difference between those two processes. Therefore, when you balance the equation you can see that it is an example of the law of conservation of mass and energy. This is a chemical change because the atoms rearrange and form a new substance with different chemical properties. It is a redox (oxidation-reduction) reaction where nitrogen is oxidized from +2 to +4 because it is losing electrons and oxygen is reduced because it is gaining electrons.
