Bond Angles

[Jasmin Argueta 1K]

Why is it that when bonds are formed we place a negative in front of the value? This is in regards to calculating enthalpy through bond angles in lecture.

[Tuong-Minh Tran 1C]

In enthalpy, the energy released by an exergonic reaction is represented by a negative value (since enegy in the system is lost), while the energy required to perform an endergonic reaction is represented by a positive value (because energy is added to the system). It happens to be that the formation of bonds is exergonic, so we place a negative in front of the value.

[Meigan Wu 2E]

Energy is required to break bonds (positive enthalpy change), while energy is released to form bonds (negative enthalpy change).

[Porus_Karwa_2E]

The formation of bonds is exothermic, thus we place a negative sign.

[Harshita Talkad 4L]

Forming bonds releases energy, so the negative sign represents the loss of energy from the system.

[ran2000]

Bond formation is exothermic while bond breaking is exothermic. Hence, when bonds are formed, since they release energy, we put a negative sign before the values.