Final answer:
Substances released in free radical and polar reaction mechanisms can include free radicals, ions, ATP, as well as neurotransmitters and hormones; the specific substances depend on the type of reaction mechanism involved. Energy is also commonly released, particularly in metabolic processes such as glycolysis.
Step-by-step explanation:
During chemical reactions, different types of mechanisms can be involved, and various substances can be released as a result. In the context of free radical reaction mechanisms, molecules typically undergo hemolytic bond breaking, leading to the formation of free radicals—unstable and highly reactive atoms or groups of atoms that have an unpaired electron.
In polar reaction mechanisms, which involve heterolytic bond breaking, ions are formed. This may occur when a molecule breaks into a cation (positively charged particle) and an anion (negatively charged particle). In biochemical pathways such as glycolysis, energy is released when molecules like glucose are metabolized. ATP is usually formed as a high-energy compound that the cell can use for various processes, but energy can also be released in forms such as heat. Similarly, the release of signaling molecules such as neurotransmitters or hormones, as elaborated in the references, are other examples of what can be released during certain reaction mechanisms.
It's important to note that when discussing energy release in the context of biological systems, this often refers to the conversion of energy from one form to another--for example, the conversion of chemical energy in organic molecules to ATP during cellular respiration.