Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

[Phys-l] Learning barriers: was Physics first



What takes away pleasure from learning? One of the factors is confusing terminology, giving new meanings to words which already refer to something in common use. This has been discussed in some of our debates. Below is an illustration, pasted from Wikipedia; the law of conservation of charge is not even mentioned.

If "oxidation" is loss of electrons then why don't they call it loss of electrons. And if "reduction" is gain of electrons then why don't they call it gain of electrons. By the way, reduction (for example in weight) is usually accomplished by loosing something, not by gaining something.

Ludwik Kowalski
Let the perfect not be the enemy of the good.

Oxidation and Reduction
The elements involved in an electrochemical reaction are characterized by the number of electrons each has. The oxidation state of an ion is the number of electrons it has accepted or donated compared to its neutral state (which is defined as having an oxidation state of 0). If an atom or ion donates an electron in a reaction its oxidation state is increased, if an element accepts an electron its oxidation state is decreased.
For example when sodium reacts with chlorine, sodium donates one electron and gains an oxidation state of +1. Chlorine accepts the electron and gains an oxidation state of −1. The sign of the oxidation state (positive/negative) actually corresponds to the value of each ion's electronic charge. The attraction of the differently charged sodium and chlorine ions is the reason they then form an ionic bond.
The loss of electrons of a substance is called oxidation, and the gain of electrons is reduction. This can be easily remembered through the use of mnemonic devices. Two of the most popular are "OIL RIG" (Oxidation Is Loss, Reduction Is Gain) and "LEO" the lion says "GER" (Lose Electrons: Oxidization, Gain Electrons: Reduction).
The substance which loses electrons is also known as the reducing agent, or reductant, and the substance which accepts the electrons is called the oxidizing agent, or oxidant. The oxidizing agent is always being reduced in a reaction; the reducing agent is always being oxidized.
The gain of oxygen, loss of hydrogen and increase in oxidation number is also considered to be oxidation, while the inverse is true for reduction.
A reaction in which both oxidation and reduction is occurring is called a redox reaction. These are very common; as one substance loses electrons the other substance accepts them.
Oxidation requires an oxidant. Oxygen is an oxidant, but not the only one. Despite the name, an oxidation reaction does not necessarily need to involve oxygen. In fact, even fire can be fed by an oxidant other than oxygen: fluorine fires are often unquenchable, as fluorine is an even stronger oxidant (it has a higher electronegativity) than oxygen.