Theory illustration by counting drawing with fads

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Lewis" theory of chemical Bonding

Inert gas electron configuration (Lewis octets)

The following Periodic Table mirrors some that the aspects that appear most commonly in essential compounds. The numbers give the variety of valence electrons held by every atom:

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Do girlfriend see any patterns? atom in the exact same column have actually the same variety of valence electrons. Atoms in the exact same row have actually varying number of valence electrons, yet the number is always 8 or less. The inert gases (blue boxes) always hold 8 valence electron (He is the exception). <1>

Lewis postulated that inert gas atoms room chemically inert since they host 8 valence electrons. The valence electron pattern in these atoms is dubbed an inert gas electron configuration. Chemists likewise call this a Lewis octet.

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Lewis suggest that other atoms become an ext stable (less chemically reactive) by adopting one inert gas electron configuration. The atoms carry out this by ionization (gaining or shedding electrons) or by sharing an electron pair with another atom.

Here are some familiar instances of "unstable" atoms (left) and chemically steady ions or molecules (right):

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Li+ has actually the exact same electron configuration together He Br- has the very same electron configuration as Kr every H in H2 "sees" 2 electrons, so every H has the very same electron configuration together He.

Review problems

Questions #1-3 are based upon the periodic Table above. I intend you to know these electron configurations without having to above the chart. Invest some time learning the chart at the height of this page, and then see how much of the complying with you have the right to do.

#1. i beg your pardon inert gas go not have actually a Lewis octet? How many valence electron does it have?

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#2. Which atoms and/or ion can accomplish inert gas electron configurations there is no achieving Lewis octets? surname them.

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#3. for each atom listed below provide a) the number of valence electron it holds, b) the atomic ion that would have an inert gas electron configuration: O, Br, P, S, K, F, Mg.

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#4. decide whether the atom in this formulas have inert gas electron configurations (note: a given formula can contain a mix of atoms with and without ideal configurations, thus you need to check every atom). Every time you uncover an atom that lacks an inert gas electron configuration, say how many valence electrons space configured roughly this atom.

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#5.

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same as #4.

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<1> due to the fact that most inert gases are chemically inert and their outer electrons are almost completely unaffected by surrounding atoms, one could argue the inert gases lack valence electrons. Thinking about things this method does not change things - atoms still shot to take on inert gas electron configuration - however it does make the phrase "Lewis octet" watch odd ("Lewis null" could make more sense).