Science, Tech, Math › Science If a Molecule Is Oxidized Does It Gain or Lose Energy? Share Flipboard Email Print Rusting of iron is an example of an oxidation reaction. Watcharapong Thawornwichian / EyeEm / Getty Images Science Chemistry Physical Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Anne Marie Helmenstine, Ph.D. Chemistry Expert Ph.D., Biomedical Sciences, University of Tennessee at Knoxville B.A., Physics and Mathematics, Hastings College Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. She has taught science courses at the high school, college, and graduate levels. our editorial process Facebook Facebook Twitter Twitter Anne Marie Helmenstine, Ph.D. Updated September 06, 2018 If a molecule is oxidized, does it gain or lose energy? Oxidation occurs when a molecule loses an electron or increases its oxidation state. When a molecule is oxidized, it loses energy. In contrast, when a molecule is reduced, it gains one or more electrons. As you might have guessed, the molecule gains energy in the process. Confused? Think about it like this. Electrons orbit the atomic nucleus, giving it electrical and kinetic energy. If you have more electrons, you have more energy. Keep in mind, however, energy input may be required (activation energy) to get a molecule to change its oxidation state.