Resources | Subject Notes | Chemistry
In chemistry, a redox reaction is a reaction in which electrons are transferred between two species. This involves two processes: oxidation and reduction. This section focuses on defining oxidation.
Oxidation can be fundamentally defined as the loss of electrons by a substance. When an atom, ion, or molecule loses electrons, it is said to be oxidized.
This process results in an increase in the oxidation state of the species.
The oxidation number is a bookkeeping system used to track the distribution of electrons in a chemical compound. It's a hypothetical charge an atom would have if all bonds were completely ionic. Oxidation is defined as an increase in the oxidation number of an atom.
When an atom is oxidized, it loses electrons, and its oxidation number becomes more positive (or less negative).
| Concept | Definition |
|---|---|
| Oxidation | The loss of electrons by a substance. |
| Oxidation Number | A hypothetical charge assigned to an atom in a chemical compound. |
| Oxidation Process | An increase in the oxidation number of an atom. This occurs when an atom loses electrons. |
Example: Consider the reaction of sodium with chlorine: $2Na(s) + Cl_2(g) \rightarrow 2NaCl(s)$
In this reaction, sodium (Na) loses an electron to become a sodium ion ($Na^+$). Sodium is being oxidized. Its oxidation number increases from 0 to +1.
Similarly, chlorine (Cl) gains an electron to become a chloride ion ($Cl^-$). Chlorine is being reduced.