What are molecules, and how are the properties of molecules different from the atoms they come from? Give an example.

Molecules are the smallest particle of a compound or element which can be found in nature as a free entity and made up of atoms bonded together. The molecules can not take part in the chemical reaction on their own directly.

An atom is on other hand is the smallest particle that does not exist free in nature and bonded together to form molecules and involves in the chemical reactions directly.

Therefore we can say that the molecules are formed by atoms while the atom exists as an entity in nature.

a. energy is absorbed in the reaction.

if in a given reaction the energy of products is greater than the energy of reactants it means that reaction is endothermic and during the reaction, the energy is absorbed by reactants. in an endothermic reaction, the products have more stored chemical energy than the reactants. and in this reaction the reactants are more stable than products before the compounds with less energy are always more stable.