학생이 chemistry에서 배운거는 bond form이 enthalphy change 만 고려한 exothermic, 아닌가요? 바이오에서는 Gibbs free energy, 즉 entrophy의 개념도 포함하고 있는겁니다. 
어쨋든 학생 말이 맞아요. 

Breaking bonds requires energy from the surroundings, 

forming bonds loses energy to the surroundings. If net bonds are formed in a reaction, it will be exothermic with respect to the system. 

If net bonds are broken during a reaction, it will be endothermic with respect to the system....

그런데 speicific 하게 hydrolysis of ATP만 따졌을때는. 

ATP hydrolysis is exothermic because the bonds involved with the hydrolysis products are in a lower energy state than the phosphoanhydride bonds involved in the ATP molecules. 이에요 그 에너지 이용해서 다르molecule의 bond가 form되는거고요. 그리고 나머지 에너지는 heat으로 lost됩니다. 결국에 전체적으로 net 으로 보면 다른 molecule의 bond가 form 되기 위해 주변으로 heat energy가 lest된거니 forming bond is exergonic 이 맞는거에요 

아래 를 읽어보면 좀더 이해가 잘되실겁니다 ^^ 출처 : https://chemistry.stackexchange.com/questions/108108/why-does-bond-breaking-in-atp-release-energy

Breaking a bond, in isolation, never releases energy. Bonding is a stable state compared to the unbonded species, where opposite charges are closer together when bonded compared to unbonded and the whole system is at a lower (electrical) potential energy. The bond broken in the hydrolysis of ATP is no different. It is a fairly weak bond, but still requires energy to be broken.

The reason there is energy released in the process is because the products formed (ADP and hydrogenphosphate/phosphate) have stronger covalent bonds (plus intermolecular forces with the surrounding solution and dissolved ions) than the starting materials. This is the case for any exothermic process. As you break the P-O bond in ATP a new P-O bond is formed in the hydrogenphosphate, but you also need to look at the interactions of the starting materials compared to the products with the solution. We should also note that the water that attacks the phosphate group in the hydrolysis reaction will then need to be deprotonated and the hydrogenphosphate ion formed will partially dissociate to phosphate, so there's a lot going on!

Also, it is worth noting that when people say "energy is released in ATP hydrolysis" they are normally referring to Gibbs Free Energy, which also includes the contribution made by the system entropy change (times temperature) as well as the enthalpy change (determined by bond and other electrostatic interaction strength). In the case of ATP hydrolysis, under most conditions, we also have an increase in the entropy of the system and this drives the process to be even more exergonic (favorable, can be used to drive other processes) than the enthalpy alone would suggest.

Please understand: the chemistry involved here is actually very complex and the total usable energy made available depends on many factors beyond the structures of the starting materials and the products. To truly understand ATP hydrolysis requires knowledge of all species' concentrations (as this affects the driving force) including various dissolved ionic species that aren't normally included in the simple reaction equation.