Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
spacerUNIT # 4  
spacerspacerIntroduction
spacerspacerObjectives
spacerspacerReading


spacer4.1 The Periods
spacer4.2 The Groups
spacerGroup IA - Alkali metals
spacerGroup IIA - Alkaline earth metals
spacerGroup VIIA - Halogens
spacerGroup VIIIA - Noble gases
spacer4.3 Metals,
spacerNonmetals,
spacerSemimetals

spacerProperties of Metals
spacerProperties of Nommetals
spacerProperties of Semimetals
spacerSummary
spacer4.4 Metallic
spacerBonding

spacer4.5 Octet
spacerRule

spacer4.6 Ions
spacer
4.7 Covalent
spacerBonding

spacerCovalent Bonding & Groups
spacer
4.8 Atomic
spacerSize

spacer
4.9 Ionic
spacerSize

spacerIonic Size of Metal Ions
spacerIonic Size of Nonmetal Ions
spacerIonic Size for Isoelectronic Series
spacer
4.10 mp/bp
spacerTrends
spacer
4.11 Metallic
spacerTrend


spacer** More
spacerspacerperiodic
spacerTrends
**


spacerspacerProblems
spacer1 | 2 | 3
spacerspacerCrossword
spacerspacerHow well do you
spacerknow your
spacerPeriodic Table?

Unit #4 THE PERIODIC TABLE

4.5 - Octet Rule

In section 3.3.2 we learned how to determine the number of valence electrons for the Representative elements. The number of dots you have around the Lewis Electron-Dot Symbols of Elements represents the actual number of valence electrons for the element.

Elements belonging to Group VIIIA are called the noble gases. These elements have 8 valence electrons and are said to have a complete octet of electrons. This is the equivalent of a filled energy level, or a closed shell. This special arrangement of EIGHT electrons makes the noble gases relatively unreactive. Although Helium is the only noble gas with two valence electrons, you will recall that the first energy level can only accomodate two electrons.

A thorough understanding of the Rule of Eight or the Octet Rule is essential for further study involving chemical bonding of atoms and the formation of compounds. It turns out that in the formation of molecules from atoms, most atoms attempt to achieve this configuration of 8 valence electrons around each atom. In order to achieve this, atoms tend to lose or gain electrons to achieve an octet of electrons.

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