Can someone explain to me the fundamental understanding of why, when two hydrogen atoms for example, release energy when they form a covalent bond? I can't seem to comprehend. Here is my reasoning, please see if this makes any sense of I am simply going in the wrong direction, I would really appreciate this. I am an undergraduate student loving the sciences and have tried figuring this out all night, it is frustrating me: The kinetic-molecular theory of matter states that all matter consists of tiny particles (everything from atoms, molecules, or ions) which are in constant motion. This means that atoms, molecules, ions, etc. all have kinetic energy associated with them on the microscopic scale known as thermal energy. I know bond formation between two hydrogen atoms occurs when two atoms (that are moving very high speeds) are stabilized due to the electrostatic attraction-repulsion stability formed between the electrons and protons of the two atoms. This constitutes a chemical bond. So, did the kinetic energy of the atoms that was moving really fast, get converted to heat given off to the surroundings, because the bond formation slowed down the thermal energy of the once separated, fast moving atoms?? I am also having a hard time understanding chemical potential energy in a covalent bond. I know that chemical bond formation within a molecules, gives rise to chemical potential energy due to electrostatic attraction-repulsion stability formed between the electrons and protons of the two atoms. Is potential energy of a chemical system, for example a molecule, visualized as the energy required to counteract the electrostatic force that holds atoms together, i.e the chemical bond? So, to break a bond we would need to increase the kinetic energy of the individual atoms so that they overcome the potential energy formed in a covalent bond by the electrostatic interactions that was holding the bond together? How do you increase the kinetic energy of an individual atom in order to overcome the potential energy of covalent bond in the molecules? They absorb thermal energy from the surroundings, correct? Thus chemical potential energy is converted to kinetic energy in bond breaking? But in bond formation kinetic energy (thermal energy) of the atoms is converted to heat and/or light?