text: Atoms that burn in the solid state are usually in molecular state. When they are burnt, combustion process, it is breakage of molecular state: to release atomic state (free radicles or ions). Afree radicle is a neutral atom with unpaired electrons. Like ions free radicles are also unstable and radily combine with another atom or ion to form a stable molecule. In combustion CO2, CO and H2O are main products besides other. Natural gas and many other gases are few examples but for solid state coal and wood are two important examples. Then Oxygen atoms combine to the burning substance to give new substance. For Example:\ni-   Coal as C atoms\nii-  Molecular Oxygen as O2 converting to 2O\niii- C+2O----CO2