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14 Cards in this Set
- Front
- Back
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Step one |
Identify individual elements |
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Elements in CN |
Carbon and Nitrogen |
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Elements in ClO4 |
Chlorine and oxygen |
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Step two |
Identify valence electrons on each element present |
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How many valence electrons does O have? |
6 |
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How many valence electrons does H have |
1 |
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Step three |
Calculate the total number of valence electrons |
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How many valence electrons does CN- have? |
10 total electrons
C = 4 valence x 1 atom = 4 electrons N = 5 valence x 1 atom = 5 electrons - = 1 extra electron x 1 charge = 1 4 + 5 + 1 = 10 |
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How many valence electrons does CH3CH2CH3 have? |
20 total electrons C = 4 valence x 3 atoms = 12 electrons H = 1 valence x 8 atoms = 8 electrons 12 + 8 = 20 |
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Step four |
Recall two basic rules of lewis structures |
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Rule one |
Hydrogen ALWAYS goes on the outside Why? Since hydrogen only had one electron, it's first valence shell only accepts 2 electrons, and EVERY bond between elements has 2 electrons. If Hydrogen is in the middle, it will have more than one bond. |
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Rule two |
Determine if the formula is obviously already written in lewis structure form or not. |
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Is CH3CH2CH3 in Lewis structure form? |
Yes.
Why? Because if it was not, it would be written as C3H8. |
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Step five |
Write all possible forms (following the rules) |
