The atoms are usually neutral state: the positive charge of the nucleus is equal to the negatively charged electrons. The agitation of a gas increases when it absorbs heat. If enough heat is absorbed, electrons are stripped from atoms and matter is ionized, saying that it is in plasma state.

All incandescent gas plasma is formed by atoms (molecules sometimes) converted to positive ions and negative electrons, all in continuous agitation. Within this gas can be also some ionized atoms and molecules (neutral particles).

Examples of gases in the plasma state are parts of the flames, gas, fluorescent tubes, the air is in the path of a beam, the matter that forms stars plasma ...