Molecular orbital energy ordering for b2, c2, and n2 sigma 2s, sigma(star) 2s, pi 2p, sigma 2p, pi(star) 2p, sigma(star) 2p. Molecular orbital energy ordering for o2, f2, and ne2 sigma 2s, sigma(star) 2s, sigma 2p, pi 2p, pi(star) 2p, sigma(star) 2p. Atoms rearrange, transforming the original substances into different substances. Atoms or molecules that compose a substance do not change their identity. The reactant that limits the amount of product in a chemical reaction, used up first. The amount of product that can be made in a chemical reaction based on the amount of limiting reactant. The amount of product actually produced by a chemical reaction. Percent yield = (actual yield/ theoretical yield) x 100% Involves the reaction of a substance with o2 to form one or more oxygen-containing compounds. A solution in which water acts as the solvent. Molarity (m) = amount of solute (in moles)/ volume of solution (in l)