In an analogous fashion, covalent bonds result in a net strong attraction between the bonding atoms. As a result the atoms come together.
Energy is released when isolated atoms form a covalent bond.
Energy must be absorbed to break the bond apart. The bond energy is the amount of energy necessary to break one mole of covalent bonds into isolated gaseous species, it is sometimes called the bond dissociation energy or bond enthalpy. As the exact bond energy of a given bond varies somewhat with the species that are linked to the other side of the central atom, average bond energies are often quoted. In summary, metallic, covalent, and ionic bonding can be pictures as shown below Mosby-Year Book Inc.