Which statement best defines oxidation?

• A. Loss of electrons
• B. Gain of electrons
• C. Sharing of electrons
• D. Formation of ionic bonds

Answer: (A)

Oxidation is the loss of electrons. When a species loses electrons in a reaction, its oxidation state increases, and that species is said to be oxidized. In redox couples, one partner loses electrons (oxidized) while the other gains them (reduced). The historical link to oxygen is old, but the modern definition centers on electron transfer and changes in oxidation state, not on oxygen itself. The other ideas describe different concepts: gaining electrons is reduction, sharing electrons is covalent bonding, and forming ionic bonds involves electron transfer that can accompany oxidation but isn’t the definition itself.