Oxidation States Refer To The Atom's Electronegativity Level, Or The Electron's Affinity For The Nucleus, In A Molecule Or Compound. An Oxidation State Is Usually Represented By A Signed Number, For Example +3 Or -2, Which Is Called The Oxidation Number. In Certain Molecules, Multiple Oxidation States Are Possible Due To A Unique Characteristic Known As Variable Oxidation State. Variable Oxidation States Occur When Electrons Are Not Shared Equally Between Two Atoms. This Occurs For A Group Of Transition Elements That Have 3 Or More Electrons In The Outer Shell. These Transition Elements Include Iron, Copper, And Chromium, Among Others. The Ability Of These Elements To Generate Multiple Oxidation States When Bonding To Other Elements Is Due To The Incomplete Filling Of Its Outermost Orbitals And The 3d Orbitals It Is Able To ‘Access’. For Example, When A Transition Element Is In An Oxidation State Of +3 Or Higher, The 3d Orbitals Become Filled With Electrons, Becoming Stable And No Longer Accessible For Other Reactions. Variable Oxidation States Are Significant, As They Can Cause Major Changes In A Molecule's Structure And Functioning. For Example, A Copper Molecule's Behavior In The Environment, Both Chemically And Biologically, May Be Heavily Influenced By Its Multiple Oxidation States. Many Proteins Have Adaptations That Allow Them To Recognize A Specific Oxidation State Of The Copper Molecule And Bind With It In Order To Produce A Desired Outcome. An Example Of This Is In The Human Brain, Where Copper Plays A Vital Role In Neuronal Development And Fertility. In Conclusion, Multiple Stable Oxidation States Occur In Transition Elements, And Are Important In A Variety Of Biological And Chemical Processes. They Can Be Used In Therapeutic Applications, As Well As To Formulate Novel Compounds And Materials. Furthermore, Understanding Variable Oxidation States Can Provide Insights Into The Behavior Of Molecules And Enable Researchers To Manipulate Them To Suit Their Needs.