Here's why:

* Bond formation releases energy: Chemical bonds form because it's energetically favorable. The atoms involved in the bond reach a lower energy state by sharing or transferring electrons.

* Breaking bonds requires energy: To break a bond, you need to put energy in to overcome the attractive forces holding the atoms together.

* Energy is conserved: Since energy can't be created or destroyed, the energy used to break a bond is released when the bond is formed again, or in a subsequent reaction.

Examples:

* Combustion: Burning fuels like wood or gasoline involves breaking chemical bonds in the fuel molecules. This releases energy in the form of heat and light.

* Cellular Respiration: Our bodies break down food molecules (like glucose) through a series of chemical reactions. The energy stored in the bonds of the food molecules is released to power our cells.

Important Note: The amount of energy released when bonds are broken varies depending on the type of bond and the molecules involved.