Why is energy released when new bonds are formedin a chemical reaction?
when two atoms approach each other two forces operate between them i.e attractive and repulsive forces( repulsion due to valence electrons) . if a particle in under the force of attraction its P.E decreases. and low energy system are stable.
so when ever electrons of two atoms come under the force of attrcation of each other nuclei they realease energy to stabilize themself.