Answer: The two elements on the periodic table that may be produced in sad reactions are Oxygen and Nitrogen.
Step-by-step explanation:
Both of these elements are part of the air we breathe and are required for survival, but under certain conditions, they can lead to sad reactions. Oxygen is required for respiration, but when it reacts with other substances in the body, it can lead to the production of free radicals, which can damage cells and cause mood disorders. Nitrogen is also required by the body, but when it reacts with oxygen and other substances in the air, it can lead to the formation of air pollutants, such as smog and ozone, which can also contribute to sad reactions.