Energy is what makes a substance react or change.
For example, a molecule that emits a certain chemical energy is a “fuel” for the molecule’s chemical reactions, and this energy is what creates the energy of the chemical reaction.
For molecules that don’t emit energy, the chemical will simply not react at all.
Chemical energy can also be used to describe the amount of energy needed to make a chemical reaction take place.
For instance, a chemical can use energy to create a chemical bond that forms a bond between two molecules.
When the bond is broken, the energy is released.
A chemical that doesn’t have enough energy to form a bond can absorb the energy released and create a new molecule, which will absorb the same amount of the energy.
Chemicals that have a high level of chemical energy can be used as fuel for reactions that will lead to new molecules.
Examples of such compounds are hydrogen, carbon monoxide, oxygen, and nitrogen.