Term
| Drawing Lewis Structures 1 |
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Definition
Write the skeletal structure (the arrangement of atoms within the molecule):
Central atom = the atom with the lowest electronegativity (usually).
Hydrogen is always a terminal atom (on the end). |
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Term
| Drawing Lewis Structures 2 |
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Definition
Count the total number of valence electrons:
Group number for each element = # valence electrons.
Add electrons for negatively charged ions.
Subtract electrons for positively charged ions. |
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Term
| Drawing Lewis Structures 3 |
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Definition
Draw a bond between the central atom and each surrounding atom.
Single bond = 1 pair of electrons |
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Term
| Drawing Lewis Structures 4 |
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Definition
Place lone pairs of electrons about each terminal atom to complete their octets.
Octet = 4 electrons pairs around an atom (eight electrons)
Hydrogen can only have 2 electrons. |
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Term
| Drawing Lewis Structures 5 |
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Definition
If there are more electrons left, place them as lone pairs on the central atom.
This will sometimes lead to an "expanded octet" around the central atom.
Expanded octet = five or six electron pairs around an atom.
Only central atoms from the third period and above can have expanded octets. |
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Term
| Drawing Lewis Structures 6 |
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Definition
If the central atom has an incomplete octet, use the electrons from surrounding atoms to make double or triple bonds.
Do not add electrons. "Borrow" them from surrounding atoms.
Double bond = 2 pairs of electrons
Triple bond = 3 pairs of electrons
Only C, N, O, P, and S form multiple bonds.
F and Cl do not form multiple bonds. |
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Term
| Drawing Lewis Structures 7 |
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Definition
Sometimes you just can't complete the octet for a central atom.
If there is an odd number of electrons, give the central atom 7 electrons instead of 8.
Boron and Beryllium just don't have enough electrons to go around and often have incomplete octets. |
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Term
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Definition
| characterized by having ring systems in which the bonding can be described as alternating single and double bonds. |
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Term
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Definition
| subdivided into alkanes, alkenes and alkynes. |
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Term
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Definition
| compounds that contain only the elements H and C. They can be divided into two classes: aliphatic and aromatic. |
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Term
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Definition
| each C atom is bonded to four other atoms and all bonds are single bonds. |
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Term
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Definition
| contains a carbon-carbon double bond. |
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Term
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Definition
| carbon-carbon triple bond. |
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