Final answer:
In the reaction of magnesium with oxygen to form magnesium oxide (MgO), magnesium undergoes oxidation, losing electrons to form Mg2+, while the oxygen molecule undergoes reduction, gaining electrons to form oxide ions, O2-. They combine to give MgO.
Step-by-step explanation:
The half-reaction for magnesium (Mg) reacting with oxygen (O) to form magnesium oxide (MgO) involves both oxidation and reduction processes. Considering the entire reaction 2Mg + O2 → 2MgO, let's focus on each half separately.
Oxidation Half-Reaction
For the oxidation half, magnesium (Mg) is being oxidized:
Mg → Mg2+ + 2e-
Reduction Half-Reaction
For the reduction half, oxygen (O2) is being reduced to form oxide anions (O2-):
O2 + 4e- → 2O2-
During this reaction, magnesium is losing electrons (oxidation) and oxygen is gaining electrons (reduction). When magnesium reacts with oxygen, it is oxidized to magnesium ions (Mg2+), and the oxygen molecule is reduced to oxide ions (O2-).
To obtain magnesium oxide, MgO, these ions combine in a one-to-one ratio to form the ionic compound:
Mg2+ + O2- → MgO