charged atom

離子(ion)是指原子由於自身或外界的作用而失去或得到一個或幾個電子使其達到最外層電子數為8個或2個的穩定結構。這一過程稱為電離。電離過程所需或放出的能量稱為電離能。
在化學反應中,金屬元素原子失去最外層電子,非金屬原子得到電子,從而使參加反應的原子或原子團帶上電荷。帶電荷的原子叫做離子，帶正電荷的原子叫做陽離子，帶負電荷的原子叫做陰離子。陰、陽離子由於靜電作用而形成不帶電性的化合物。
與分子、原子一樣，離子也是構成物質的基本粒子。如氯化鈉就是由氯離子和鈉離子構成的。
Ion

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This article is about the electrically charged particle. For other uses, see Ion (disambiguation).
"Multivalent" redirects here. For the Multivalent browser, see Multivalent (browser).


圖片參考：http://upload.wikimedia.org/wikipedia/commons/thumb/6/6f/Nitrate-ion-elpot.png/200px-Nitrate-ion-elpot.png



圖片參考：http://en.wikipedia.org/skins-1.5/common/images/magnify-clip.png
An electrostatic potential map of the nitrate ion (NO3−). Areas coloured red are lower in energy than areas coloured yellow
An ion is an atom or group of atoms that normally are electrically neutral and achieve their status as an ion by loss or addition of one or more electrons. The simplest ions are the proton (a hydrogen ion, H+, positive charge), and alpha particle (helium ion, He2+, consisting of two protons and two neutrons). A negatively charged ion, which has more electrons in its electron shells than it has protons in its nuclei, is known as an anion (pronounced [ˈænaɪən]; an-eye-on) due to its attraction to anodes. A positively-charged ion, which has fewer electrons than protons, is known as a cation (pronounced [ˈkætaɪən]; cat-eye-on) due to its attraction to cathodes. An ion consisting of a single atom is called a monatomic ion, and an ion consisting of multiple atoms is called a polyatomic ion. Larger ions containing many atoms are called molecular ions. The process of converting electrically neutral atoms or molecules into ions and the state of being ionized is called ionization. The recombining of ions and electrons to form neutral atoms or molecules is called recombination. A polyatomic anion that contains oxygen is sometimes known as an oxyanion .
Ions are denoted in the same way as electrically neutral atoms and molecules except for the presence of a superscript indicating the sign of the net electric charge and the number of electrons lost or gained, if more than one. For example: H+, SO42−.





Contents[hide]

1 History
2 Etymology
3 Formation

3.1 Formation of polyatomic and molecular ions
3.2 Ionization potential
4 Ions

4.1 Anion
4.2 Other ions
4.3 Plasma
5 Applications
6 Common ions
7 References
8 External links