When magnesium reacts with oxygen, you would see a bright, white, and very intense light. Here's a breakdown of what happens:

* Magnesium is a highly reactive metal: It readily combines with oxygen in the air.

* Exothermic Reaction: The reaction between magnesium and oxygen releases a large amount of energy, causing the magnesium to heat up and glow brightly.

* Formation of Magnesium Oxide: The reaction produces a white powder called magnesium oxide (MgO).

* Flames: The intense heat of the reaction can cause the magnesium to ignite and burn with a bright white flame.

Safety Precautions:

* Never handle burning magnesium directly: The intense heat and light can cause serious burns.

* Always perform the reaction in a well-ventilated area: The reaction produces smoke, which can be irritating.

* Use safety goggles and gloves: These protect your eyes and hands from the heat and light.

If you're interested in seeing this reaction, you can find demonstrations online or in chemistry textbooks. However, remember to always prioritize safety and follow proper procedures.