The Octet Rule

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Mind Map by , created over 6 years ago

Science 10 Mind Map on The Octet Rule, created by syylex403 on 05/24/2013.

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Created by syylex403 over 6 years ago
Matter
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Elements
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The Periodic Table
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DEV I Part II
d owen
1PR101 2.test - Část 15.
Nikola Truong
Compounds with Multivalent Elements
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Atomic Number, Isotopes, Mass Number, Atomic Molar Mass
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Ionic Compounds
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Polyatomic Ions
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Modèles Atomiques
Ophelia Goasdoue-Wallace
The Octet Rule
1 Another way to understand the patterns by which atoms gain or lose electrons is to look at their energy levels. All the noble gases have filled energy levels. So it is possible to restate the pattern for ion formation in a new way: Atoms tend to gain or lose electrons so that they end up with completely filled energy levels. Notice that the noble gases neon and argon each have 8 electrons in their valence energy levels. The Octet Rule (also called the rule of 8) states that atoms bond in such a way as to have 8 electrons in their valence energy level. ("Oct-" means 8, so an octet is a group of 8.) This is just another way to say that atoms tend to be stable with full outer energy levels. However, it is a handy rule for figuring out an elements charge or valence by looking for the octet.
1.1 For example, chlorine is just below fluorine in group 17. All atoms in this family have 7 valence electrons. By the octet rule, fluorine will have an octet of electrons (8 electrons) in its valence energy level if it gains an electron to form the F ion. This means that a chlorine atom will also gain one electron, forming the Cl ion.
1.1.1 The exceptions to the octet rule are hydrogen, lithium, and beryllium. They each need only two electrons in their valence energy levels because their nearest noble gas, helium, has two electrons.
1.1.1.1 The situation is more complicated with transition metals. In the periodic table, these are all the metals from scandium to zinc inclusive, and any metals directly below them. All metals tend to lose electrons to become more stable, but it is difficult for atoms to lose more than about three electrons. This is because, every time an electron is lost, the remaining electrons are held more tightly by the nucleus. Gold, for example, can lose at most three electrons, to form Au . Depending on the chemical conditions, iron can lose either two or three electrons, to form Fe or Fe . The elements boron, silicon, and carbon rarely form ions. Predicting the number of electrons transition metals will lose is difficult. Consult the periodic table for the ion charge for these elements. The first charge given is the most common.

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