Here's how to break down the oxidation half-reaction for the reaction:

2 Mg + O₂ → 2 MgO

1. Identify the oxidation and reduction:

* Oxidation: Magnesium (Mg) loses electrons and goes from an oxidation state of 0 to +2 in MgO.

* Reduction: Oxygen (O) gains electrons and goes from an oxidation state of 0 in O₂ to -2 in MgO.

2. Write the half-reaction for oxidation:

The oxidation half-reaction focuses on the species that is being oxidized (Mg):

Mg → Mg²⁺ + 2e⁻

Explanation:

* Mg is the magnesium atom in its elemental form.

* Mg²⁺ is the magnesium ion, which has lost two electrons.

* 2e⁻ represents the two electrons that were lost during oxidation.

Important Note: You need to balance both the atoms and the charge on each side of the half-reaction.