Chemistry_Understanding History Of The Oxidation State Concept

The first philosophical and scientific interest was the history and genesis of the oxidation state of chemical processes presently known as redox reactions and combustion.

Empedocles, the Greek scientific philosopher, defined fire as one of the four constituents of matter. In recent years, the concept of phlogiston has gained scientific traction. In 1697, G.E. Stahl, a German scientist, proposed this concept for the first time. As previously established, when matter burns, it emits a basic constituent known as phlogiston.

As a result, charcoal burning was considered to be the release of phlogiston from carbon into the atmosphere. The concept was also applied to processes other than combustion; for example, when recovering metal from its oxide by heating it with charcoal, phlogiston was considered to be transferred from carbon to the oxide.

The limited air capacity in a confined container to promote combustion was thought to be due to phlogiston saturation. The phlogiston hypothesis resulted in the idea that a metal oxide, such as mercury(II) oxide (HgO), was a chemically simpler material than the metal itself: the metal could only be created from the oxide by adding phlogiston. On the other hand, the phlogiston theory could not explain the weight gain that occurs when an oxide is produced from metal.

Oxidation state

A measurement of an atom’s degree of oxidation in a material.

It is described as the charge that an atom may have if electrons were counted per a predetermined set of rules:

• (1) the oxidation state of a free metal (uncombined element) is zero
• (2) the oxidation state of a simple (monatomic) ion is equal to the ion’s net charge
• (3) when hydrogen and oxygen are included in most compounds, their oxidation states are 1 and -2, respectively.

(Exceptions include hydrogen having an oxidation state of -1 in active metal hydrides, such as LiH, and oxygen having an oxidation state of -1 in peroxides, such as H2O2);

• (4) In a neutral molecule, the algebraic total of the oxidation states of all atoms must be zero. Still, in ions, the sum total of the oxidation states of the component atoms must be equal to the applied on the ion.
• Sulphur oxidation states in H2S, S8 (elementary sulphur), SO2, SO3, and H2SO4 are, for example, -2, 0, +4, +6, and +6.
• The higher an atom’s oxidation state, the greater its degree of oxidation; the smaller its oxidation state, the greater its degree of reduction.

Formal oxidation states are calculated.

There are two popular methods for calculating an atom’s oxidation state in a chemical.

The first is used for molecules with a Lewis structure, which is common for organic molecules, but the second will be used for simple compounds (molecular or not) that do not require a Lewis structure.

It is important to note that an atom’s oxidation state does not represent its “real” charge: this is especially true at high oxidation states when the ionisation energy necessary to generate a massively positive ion is significantly larger than the energies accessible in chemical processes. The allocation of sharing of electrons in computing an oxidation state is solely a formalism but one that is important for understanding many chemical events.

What is the definition of oxidation?

Oxidation occurs when oxygen molecules come into contact with other substances.

It is just an atom’s elevated oxidation state as a result of a chemical process. It is the exact opposite of the reduction process. The transport of electrons is necessary in both processes.

Oxidation is a chemical process that includes the flow of electrons between the components of any molecule. When an element gives electrons, the process’s character is revealed. A higher oxidation state further distinguishes it. The interaction of iron (Fe) with oxygen is a common example of oxidation (O2). The interaction of these two elements produces rust, in which the electrons wasted by iron are acquired by oxygen.

The Highest and the Lowest Oxidation States

While oxidation is the process of increasing the oxidation state, a reduction is a process of decreasing it. Nevertheless, quantity limitations for the state have been found, with the maximum O.S being +9 for tetroxoiridium and the lowest being -4 for carbon in methane or CH4.

In conclusion

The notion of oxidation states evolved from Antoine Lavoisier’s oxygen-based dualism theory of chemistry. At this point, the terms oxidation and reduction first arise in the literal meaning of a reacting element that has oxygen and something opposite to it. Irrespective of several researches, no attempt was made to stop using the words oxidation and reduction to describe the interactions of salts and other substances that were now found to carry no oxygen. Chemists concluded that the development of positive valency of an atom corresponds to oxidation, whereas the negative valency is taken with corresponds to the reduction, following the discovery of the ionic hypothesis of disconnection in electrochemistry and the electronic theory of bond formation and structure. Following that, scientists made reference to an element’s numerous oxidation states and formally established the words, oxidation number or oxidation state, as well as the parallel phrase oxidation potential.