[Riyam Alenezi]

My text book is the worst at explaining lol, its just too vague!! Can anyone please answer my questions about this so I get it, heres the para:

''A change in energy, either an endothermic change or an exothermic change is a sign that a chemical reaction has taken place. Most chemical reactions are exothermic.''
(Question1: Don't they mean a change in state?? What do they mean a change in energy?? Someone plz explain this )

''Most chemical reactions are exothermic because  reactants lose energy in the form of heat and light to form more energetically stable products of lower energy.
In exothermic reactions the reactants are higher in energy than the products. In endothermic reactions the reactants are lower in energy than the products''
(Question2: what is this topic about because my book says its about 'chemical changes' but I need something more specific to google and research it by, or is that the most specific it can get?''

also what does combust mean?
and when bonds break you supply it with energy and according to my book it is endothermic. So basically endothermic means like the energy is given to the chemicals instead of given out? So what happens after you supply energy to the compound to break its bond, where does that energy go?

And how is energy released when bonds are formed??? it seems a bit random like a summary, I need an explanation on HOW this happens, I need to understand it like whats actually happening to make energy be released. Thanks

[Enthalpy]

A bond is a better organisation of electrons from two atoms. The formation of a bond releases energy, breaking the bond absorbs some.

Nearly always, reactants and products are molecules, with bonds already formed. As compared with individual atoms, the compounds have already lost much energy. Reactions only reorganize the atoms into different molecules; the heat released or absorbed by the reaction is generally less than what the formation of any of the compounds from the atoms would release. That's why lone atoms are scarce on Earth, except for noble gases.

In an exothermic reaction, the products' bonds are stronger (or rather, they release more energy) than the reactants' ones - endothermic is the opposite.

One could add subtleties, for instance interactions between the molecules, heat stored in the vibrations... Often, chemical bonds are stronger than those, and suffice to determine exo vs endo-thermic.

Sidenote: the release of energy is not the absolute criteria to determine whether a reaction goes in one direction or the other. Many endothermic reactions happen spontaneously.

[Riyam Alenezi]

''As compared with individual atoms, the compounds have already lost much energy.''since the atoms became compounds and so released energy right? that's what u mean?

 ''Reactions only reorganize the atoms into different molecules; the heat released or absorbed by the reaction is generally less than what the formation of any of the compounds from the atoms would release. That's why lone atoms are scarce on Earth, except for noble gases.'' so when bonds are formed they also absorb energy as well as release it?? and u just mentioned that the bonds formed and the heat RELEASED or absorbed by the reaction is generally less than the formation of any of the compounds from the atoms would RELEASE.  so u basically just said the heat released is less than the heat released?? I don't get it, im a beginner at this topic not a novice so I need deep explanation. 

''In an exothermic reaction, the products' bonds are stronger (or rather, they release more energy) than the reactants' ones'' but reactants don't have bonds, unless they where molecules?

''One could add subtleties, for instance interactions between the molecules, heat stored in the vibrations... Often, chemical bonds are stronger than those, and suffice to determine exo vs endo-thermic.Sidenote: the release of energy is not the absolute criteria to determine whether a reaction goes in one direction or the other. Many endothermic reactions happen spontaneously.''
I need this simplified or explained more clearer, im only 15 lol I cant understand this summary alone sorry I don't understand

[Corribus]

Formation of bonds between two atoms releases energy. Think of it this way: it takes energy to pull atoms apart, because if this wasn't the case, atoms wouldn't be stuck together everywhere. And you wouldn't exist.

BUT not every bond is the same. It takes more energy to pull some atoms apart than others.

In a chemical reaction between two molecules, some bonds are broken and other bonds are formed. So, you have to put energy into the system to break the bonds, and then you release some energy when you form new ones. In an exothermic reaction, the energy you release when you form the new bonds in the product is larger than the energy you have to spend to break the old bonds in the reactant. This means that a net amount of energy is released into the environment - exothermic reactions give off heat. On the other hand, in any endothermic reaction, the energy you release when you form new bonds in the product is smaller than the energy you have to spend to break the old bonds in the reactant. This means that a net amount of energy is absorbed from the environment - endothermic reactions take heat away from the environment.