An atom with a non-neutral charge. It has either more electrons than protons or more protons than electrons. Polyatomic Ions are another form of ion. Both types combine to for Ionic Bonds but only monoatomic ions form Metalic Bonds.

Dialogue by Plato, about a conversation between Socrates and a rhapsode, a professional reciter of poetry, named Ion. It is one of the Socratic Dialogues of Plato, his earlier works, in which Socrates is presented simply challenging the views and opinions of another, and not espousing any particular philosophy of his own (though certain beliefs emerge).

The dialogue begins as Socrates sees Ion coming from Epidaurus, having just competed in a competition of rhapsodes. The conversation soon turns to the question of expertise, or techne; and Ion soon makes the preposterous claim that because he knows the poets, especially Homer, and since the poets write about all subjects, he must naturally be skilled in all things. With its subject set, the remainder of the dialogue is a deconstruction of this statement. Socrates procedes to ask Ion several questions about his art and his beliefs about the origin of his skill. The most famous passage of the dialogue is commonly called the "magnet analogy":

For your skillful recitation of Homer is not an art, as you just claimed, but a divine force which moves you, just as in that type of stone which Euripides called a "Magnet", but most people know as a "Heracleian". And indeed these stones do not only attract rings and pieces of iron, but then convey this same ability to the rings so that they can in turn do the same thing which the stone does, to attract other rings, so that sometimes a great chain entirely of iron and rings is formed from the others. This power is thus conveyed to the others from just that one stone. In just this was does the Muse place her inspiration, and a chain is formed from the inspirations of the other ones who are inspired. For all of the poets of epics take virtue not from their skill but, because they are inspired and possessed, compose all of these great poems, and the lyric poets just the same, just as the Corybantic dancers dance when they are no longer within their right minds, so do the lyric poets, no longer within their right minds, make their beautiful songs...(Ion 533d1-534a2)

This is really the center of the dialogue; the reciter of poetry is at the end of a very long chain, flowing through the poet himself, and beginning with the Muse. Since the poet is "possessed" (taken hold of) by the god while he writes, he can not be the source of the poetry, and so it is unneccessary, and unlikely, that he has any particular or specialized technical knowledge. The passage is one of the crucial points for the argument about the nature of possession and divine inspiration in the ancient world; a man who is "possessed" is "ouk emphrenes", "not in his mind", and suggests a certain internal translation of control has taken place.

The remainder of the dialogue is an application of this fundamental principle; Socrates has already proven that the poet and rhapsode do not possess techne, and it remains only to provide examples. He asks Ion to recite several passages of Homer to demonstrate why, if Homer writes about physicians and chariot-racing, he does not necessarily know anything about medicine or chariots. The dialogue ends, of course, with Socrates' argumentative victory, and Ion's shame-faced retreat.

It would be foolish to read truly modern literary theory into the Ion, but in a sense this is the precursor to the modern removal of the author from the a work's interpretation. Plato, in the voice of Socrates, is arguing that the author is in effect a medium of literature, not its source, and so his personal involvement becomes ultimately irrelevant. It is important also to remember that any reading of Plato is a process in which the reader plays a crucial role; Ion is not, in the same sense that Gorgias or Alcibiades are in the later dialogues, a particularly competent adversary for Socrates. We as readers are naturally expected to challenge the argument and find holes in the philosophy, a continued response to the general philosophical problem which Ion and Socrates have begun.

Introduction

This writeup is about the meaning of the word ion as it is definied in physics and chemistry. In these sciences, an ion is essentially a charged atom or molecule. This means the particle has either one or more extra electrons, or is missing one or more electrons. If it is missing electrons, it is called a cation, and is positive; if it has extra electrons, it is called an anion and is negative.

Properties

One of the most obvious things about an ion is that it is charged. As such, it is affected by electric fields. This means, for instance, you can accelerate it in a particle accelerator. It also means that cations and anions attract each other. As such, it is almost impossible to have a clump of cations in one place and a clump of anions in another, because the electric force is overwhelmingly strong. If you were to take for instance one gram of table salt, split it in sodium cations and chloride anions, and put them on opposite sides of a spoon, the the electric force between them would be around 10²⁰ Newton, which is comparable to the force that keeps the earth in her orbit. As such, separating significant numbers of charges is pretty much impossible, and ionic matter is largely mixed evenly. This is called quasi-neutrality.

Apart from this rather impressive physical property, there is also a chemical change. Because the chemical properties of an atom or molecule are determined by the electrons surrounding the nucleus, having an extra or missing electron makes the particle "behave" as a different atom chemically. For instance, a fluorine cation has one extra electron. s such, it has the same number of electrons a neon, a noble gas. This configuration is chemically quite stable. As such, fluorine, and many other substances, are often or almost always found in this ionic form.

Occurence

Where do we find ions? Well, pretty much all over the place. I'll summarize three places where ions are commonly found

1. In a salt: A salt is defined as a substance that consists of ions. Table salt is just one example of a salt. Salts are typically formed when a substance that easily loses electrons, such as a metal, meets a substance that easily accepts them, such as a halogen or an organic compound. Because of the strong ionic bonds, salts are quite stable; most have a very high melting points.
2. In a polar solvent: Some salts can dissolve in polar solvents, such as water. These dissolved ions are called electrolytes. In the human body, these electrolytes play a crucial role.
3. In a plasma: Plasmas are essentially energetic gases, in which some of the molecules are split in ions and free electrons. Most of these ions are cations; anions are more rare, as the plasma is so energetic the free electron state is preferable.

It is interesting to note that both the solution and the plasma are decent to good conductors of electricity. If a salt is melted, it will conduct electricity as well.

Conclusion

This is no more than a short and condensed summary on what an ion is; one could probably spent a lifetime researching ions. The most salient features are that they have an electrical charge, which changes their physical behavior. Furthermore, the extra electrons change the chemical behavior. Ions are essential for biological processes.

I"on (I"on), n. [Gr. 'io`n, neut, of 'iw`n, p. pr. of 'ie`nai to go.] (Elec. Chem.)

One of the elements which appear at the respective poles when a body is subjected to electro-chemical decomposition. Cf. Anion, Cation.

 

© Webster 1913

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I"on, n.

1.

One of the electrified particles into which, according to the electrolytic dissociation theory, the molecules of electrolytes are divided by water and other solvents. An ion consists of one or more atoms and carries a unit charge of electricity, 3.4 x 10^-10 electrostatic units, or a multiple of this. Those which are positively electrified (hydrogen and the metals) are called cations; negative ions (hydroxyl and acidic atoms or groups) are called anions. Thus, hydrochloric acid (HCl) dissociates, in aqueous solution, into the hydrogen ion, H+, and the chlorine ion, Cl-; ferric nitrate, Fe(NO₃)₃, yields the ferric ion, Fe+++, and nitrate ions, NO3-, NO3- , NO3-. When a solution containing ions is made part of an electric circuit, the cations move toward the cathode, the anions toward the anode. This movement is called migration, and the velocity of it differs for different kinds of ions. If the electromotive force is sufficient, electrolysis ensues: cations give up their charge at the cathode and separate in metallic form or decompose water, forming hydrogen and alkali; similarly, at the anode the element of the anion separates, or the metal of the anode is dissolved, or decomposition occurs.

2.

One of the small electrified particles into which the molecules of a gas are broken up under the action of the electric current, of ultraviolet and certain other rays, and of high temperatures. To the properties and behavior of ions the phenomena of the electric discharge through rarefied gases and many other important effects are ascribed. At low pressures the negative ions appear to be electrons; the positive ions, atoms minus an electron. At ordinary pressures each ion seems to include also a number of attached molecules. Ions may be formed in a gas in various ways.

 

© Webster 1913