Terminology

In this lesson we will use a number of terms with which you need to be very careful to make sure that you use and interpret them correctly. Sometimes you need to use the context to get the proper meaning. For example, the phrase "he burns" doesn't mean quite the same thing in these two sentences: "He burns the trash." "He burns at the stake."

Four terms in particular will come up again and again and you must be able to define and identify those four terms.

	Oxidation is a process and it means the loss of electrons.
	Reduction is also a process and it means the gain of electrons.
	Oxidizing agents are those chemicals which cause oxidation to occur. That does not mean that they become oxidized; it means they cause oxidation.
	Reducing agents cause reduction to occur. A reducing agent causes something else to gain electrons.

Along with those four terms you will hear lots of other terms associated with oxidation and reduction. Although you may not be called upon to define those terms specifically, you will need to understand what they mean in order to understand questions and be able to relay your information to other people. To assist you in this, there is a long list of terms which are used with oxidation in example 12 in your workbook. What follows is an expansion on that list, if you need or want more explanation than what is given in the workbook.

The first one is simple. Oxidation is the process of losing electrons.

The word oxidize, however, does create some problems in the way that our English language works. Some verbs are transitive verbs; some are intransitive. If you are not familiar with those terms, you can check with an English instructor; but essentially they are the active and passive forms of the verbs.

	As pointed out in the example, oxidize can either mean to lose electrons.
	Or, it can mean to cause the loss of electrons.
	Chemically, they are related but opposite phenomena, even though they have the same verb used to identify them. As an example, if you say that "iron oxidizes," you mean that the iron goes through the process of oxidation. If you say that "oxygen oxidizes," you mean that oxygen causes the process of oxidation to occur.
	There's quite a difference between being oxidized and causing oxidation, but the same verb is used. So you have to be very careful in how you use that verb in context and also how you interpret it when you read it or hear it. You must pay very close attention to the context in which it's used, and if you have any questions about it on a test or quiz or problem set, ask whether that verb means to go through the process of oxidation or to cause the process of oxidation.

The word oxidized has the same problem. It can be the past tense of the verb oxidize. "The tin can oxidized" or "oxygen oxidized the tin can." Whether you are talking about the passive or active form makes a big difference in terms of what is gaining electrons and what is losing electrons. The subject of the sentence may be the cause of oxidation or the object of oxidation, so again the context is very important. The word can also be used as an adjective. "Rust is one form of oxidized iron."

Next, the terms oxidized form and oxidized state refer to the condition of having fewer electrons than some other form or state of the same element. For example, sodium can exist either as Na or as Na⁺. Na⁺ is the oxidized form or oxidized state of sodium. Some chemicals have three or more different oxidation states, so when you say the oxidized state of something like iron, you have some choices to make. Do you mean the +2 or the +3 state? It's obvious that you don't mean the 0 state. If you say the reduced form, you might mean the 0 or the +2 state (but not the +3). So these phrases can be somewhat ambiguous.

The oxidation state is a numerical value associated with the condition of having lost or gained a certain number of electrons. Unlike most of these terms, this one does not have a corresponding reduction term. The oxidation state simply means how many electrons has it lost or gained. If the element has lost electrons, then it will have a positive state. If it has gained electrons, that is, if it has been reduced, then it will have a negative oxidation state. If it has neither lost nor gained electrons, then it will have a 0 state.

Oxidation number is a phrase that can be used interchangeably with oxidation state. The only real distinction is that it refers specifically to the number rather than the condition.

Oxidizing agent is a chemical that causes oxidation to occur.

A couple of terms that you won't run into are oxidizer and oxidizee, although in some ways they would be a very logical set of terms.

There are parallel terms for reduction, which are not shown here. Reduction is the process of gaining electrons. Reduce means both to go through the process of reduction and to cause the process of reduction to occur, and so on. There are parallel terms for reduction for all of these terms except oxidation state and oxidation number.

Top of Page

Back to Course Homepage

E-mail instructor: Eden Francis

Clackamas Community College
Š1998, 1999 Clackamas Community College, Hal Bender