In some chemical reactions, such as photosynthesis, several different compounds take part in the reaction. How do you think that atoms present at the end of this kind of reaction compare to the atoms present at the beginning of the reaction? Explain.

The atoms present at the beginning of the reaction is equal to the atoms present at the end of the reaction. This is because matter can neither be created nor be destroyed in an ordinary chemical reaction.

Explanation:

During photosynthesis, 6 molecules of water react with 6 molecules of carbon dioxide to form 1 molecule of glucose and 6 molecules of oxygen. The equation for the photosynthesis reaction is

6CO2 + 6H2O --> C6H12O6 + 6O2

At the beginning of the reaction, there is 6 carbon atoms, 18 oxygen atoms and 12 hydrogen atoms while at the end of the reaction, there is 6 carbon atoms, 12 hydrogen atoms and 18 oxygen atoms.  This is because according to the law of conservation of mass and matter, it can neither be created nor be destroyed in an ordinary chemical reaction. The number of atoms present at the beginning of the reaction must be equal to the number of atoms present at the end of the reaction.