Chemical and Exothermic Change: Explanation

When magnesium is burnt, heat and light are produced. This is classified as a chemical and exothermic change. Let's break down the explanation into different points:

1. Chemical Change:
A chemical change refers to a process in which substances undergo a transformation, resulting in the formation of new substances with different chemical properties. In the case of burning magnesium, a chemical reaction occurs between magnesium and oxygen in the air, leading to the formation of a new compound, magnesium oxide (MgO).

The chemical equation for this reaction is:
2Mg + O2 → 2MgO

During this chemical change, the magnesium atoms lose two electrons each to form positively charged magnesium ions (Mg2+). The oxygen molecules gain these electrons to form negatively charged oxide ions (O2-). The positively charged magnesium ions and negatively charged oxide ions then combine to form the solid compound, magnesium oxide.

2. Exothermic Change:
An exothermic change is a process that releases energy in the form of heat. When magnesium burns, it undergoes an exothermic reaction, releasing a significant amount of heat in the process. This heat energy is the reason why the burning magnesium produces a bright white light.

The heat is released due to the highly exothermic nature of the reaction between magnesium and oxygen. The energy released is a result of the formation of new chemical bonds in the magnesium oxide, which are more stable than the bonds in the reactants (magnesium and oxygen). This excess energy is released as heat and light.

Conclusion:
In conclusion, the burning of magnesium is a chemical change because it involves the formation of a new compound, magnesium oxide. It is also an exothermic change because it releases heat and light energy. The combination of these factors classifies the burning of magnesium as a chemical and exothermic change.