Chemical Reactions

All processes in  nature have the tendency to find the status of minimum energy.

Regarding the world of atoms and molecules that means: Valence electrons on an energy level where only a part of possible positons is occupied will prefer to jump to a free position of a lower energy level of another atom or molecule if possible. If this reaction takes place, both atoms will be connected to a new molecule because due to this position change the atom which lost the electron will receive positive charge, the other partner negative charge. The energy level of the new molecule will be lower than the addition of energies of the two atoms or molecules before the reaction.

This process is the basic for all chemical reactions.

A molecule will be saturated and stable as soon as all positions for valence electrons on its maximum energy level are occupied. As long as it is not it will try to find find further electrons to incorporate.

chemical reaction
If the electrons of two hydrogene atoms combine to one completed electron shell, a chemically stable H2 molecule is formed

A group of stable and saturated molecules may meet another group of molecules of different chemical character but which is also stable and saturated.

It may be, that the elements of the molecules of both groups could form a third type of molecules which would have an even lower energy level than the molecules of the groups before. A very simple mixture of such molecules are hydrogene molecules together with oxygene molecules:

2H2 + O2 → 2H2O

The difference of energy resulting from such a reaction is disipated by radiation (heat). Such a reaction is designated as "exothermal reaction".

The reaction may be spontaneous so that it takes place just caused by the mixture without any furtfer stimulation.

It may also be necessary to stimulate the reaction by intruducing a starter energy (ignition) like in case of the hydrogen/oxygen reaction above.

It may also be necessary to add a catalysator. The catalysator is a third reaction partner which will be involved in the reaction but which is not be an element of the final reaction products.

Another example for a reaction of molecules to new molecules of lower energy level (more stable) is the reaction to polymers of higher length:

polymerisation
Hydrocarbon monomers react to polymers because of lower energy of the polymer.

A plasma is a status of matter, where a large amount of molecules is transfered to an unstable und unsaturated status which enables very rapid combinations to new partnerships (molecules):

  1. the essential of a plasma: the matter is devided into negative and positive charged components. This may be the separation into positive and negative ions or into positive ions and negative free electrons.
  2. Not alle molecules are devided into positive and negative fractions. Often electrons are only stimulated to a higher energy level without leaving the atom. This is the status of stimulated atoms.
  3. Molecules may be cracked into two or more fractions where all fractions will be electrically neutral but no more saturated, because  the valence electrons of maximum energy have been separated. These fractions are calles "radicals". All radicals have the aim to find new partners to complete to a new stable molecule.

Ions, stimulated atoms and radicals are extremely reactive. They are the "Active Species" of the plasma.