Question about Chemical Bonds

[SoldierFall]

Lets say we have Hydrogen and Oxygen. When they combine, electrons are shared between the atoms. Do electrons lose energy when this happens?

[mississippichem]

Lets say we have Hydrogen and Oxygen. When they combine, electrons are shared between the atoms. Do electrons lose energy when this happens?

 

Yes. Bond forming events are exothermic. If two unpaired electrons combine or two ions come together (the two ways most bonds are formed), then the system has a achieved a lower energy state than before.

[technie]

TO answer your question, when bonds are formed, it is exothermic, or it releases energy, when bonds are broken, it is endothermic, it requires energy to break them. usually, a reaction between 2 molecules have endothermic and exothermic reactions, to firstly break the bonds of each molecule, then to reform into the new products. The energy states against a graph which shows the different amounts of energy to break bonds then to reform are then viewed as a whole to determine if a reaction is an overall endo or exothermic reaction

[Chap]

I think you should consider it as the whole system (molecule) rather than the individual electrons. Usually, a reaction is exothermic. The resulting molecule will have lower energy than the initial ones. However, there are reactions which are endothermic; photosynthesis is a very good example. In these reactions, energy is gained by the system from the environment. Therefore the resulting molecule will be of higher energy than the initial ones.

 

Endothermic reactions occur due to the involvement of entropy. If the product has a very high entropy compared to the reactants, then the reaction will proceed even if the reaction is endothermic.

 

Hope that answers your question.