In nature, all processes prefer to find the status of the lowest energy level. In respect of atoms, this means: Valence electrons at an only partially occupied energy level of the atomic shell will, if the possibility exists, search for a free space at a lower energy level of another atom. Together, the two atoms form a molecule and in total assume a lower energy level than the individual atoms did before. This bond of two atoms is a chemical reaction. The molecule’s energy level is described as overall saturated, i.e. the molecule’s highest energy level is fully occupied with electrons .
If nature takes its course, there are only molecules with saturated energy levels. However, molecules of different structure can also meet, which in a different distribution of atoms would form molecules that occupy an overall lower energy level. These two types of molecules can then react in a chemical reaction to form new molecules. But this is not necessarily the case: Some molecules spontaneously react to form new molecules, others require kick-off by energy supply and/or a catalyst. The chemical reaction between hydrogen and oxygenthe substrates to remove contaminations. In nature, both form diatomic molecules O2 and H2. The bond H2O (water), however, is much lower in energy. Therefore, whenever an oxygen molecule finds two hydrogen molecules, the following reaction will occur: 2H2 + O2 → 2H2O Another reaction to form a lower-energy state is the polymer reaction in which polymers are generated from hydrocarbon monomers:
However, this reaction is not spontaneous but needs to be induced. This type of chemical reactions occur all the time in living organisms. In a plasma, there is no “undisturbed nature” but a large number of atoms and molecules whose resting state is interfered with by the supply of energy.
- Electrons are removed from atoms: → Ions
- In other atoms, electrons are raised to higher levels: → Excited atoms
- Molecules are broken apart which generates atoms with a non-saturated energy level at the breaking points → Radicals
All this particles – ions, excited atoms and radicals (“Active species“) are looking to find reaction partners to enter a chemical reaction as fast as possible.