Covalent Bonds and Bond energy

Covalent bonds are a result of the sharing of the electrons of two nonmetal atoms. Both atoms involved in the bond share electrons to fill their particular octet. Each atom brings to the bond, the number of valence electrons and when the two combine, the octet is satisfied.


https://en.wikipedia.org/wiki/Covalent_bond

Energy is released when two ions are attracted to one another and form an ionic bond. when a bond is broken, it takes energy to do so. The energy required to break a bond is called bond energy. The amount of energy needed to form a bond is identical to the energy needed to break the bond.


http://www.science.uwaterloo.ca/~cchieh/cact/c120/bondel.html

here are some helpful websites
http://chemwiki.ucdavis.edu/Core/Theoretical_Chemistry/Chemical_Bonding/General_Principles_of_Chemical_Bonding/Bond_Energies

https://en.wikipedia.org/wiki/Bond_energy

http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch8/valenceframe.html