heat of formation vs bond energy

[Gnyc123]

how come sometimes heat of formation is 0 for O2 but sometimes it is given a bond energy that has to be used?

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[Teleologist]

The standard heat of formation for diatomic oxygen is 0 because at standard thermodynamic conditions (for all those of you thinking this implies 298 K, you're dead wrong) you don't need to form dioxygen ... it exists ... all around you ... and inside you.

The bond energy or bond dissociation enthalpy is the energy needed to homolytically cleave the bond. Not sure about how this got conflated with heat of formation.

 

[Gnyc123]

thank you!