The free atoms and molecules now combine with oxygen from the air, forming stronger bonds and thus releasing thermal energy. The random kinetic energy of these fast molecules is transferred in collisions to neighboring atoms and molecules, breaking their bonds, etc. When you bring two objects of different temperature together, energy will always be transferred from the hotter to the cooler object. The objects will exchange thermal energy, until thermal equilibrium is reached, i.e. until their temperatures are equal. We say that heat flows from the hotter to the cooler object.
Heat is energy on the move .
Heat will always flow from a hotter to a cooler object, without an external agent doing work. A difference in temperature always results in heat flow. There are three different ways for heat to flow from one object to another. They are conduction , convection , and radiation . The atoms in a solid vibrate about their equilibrium positions.