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Lewisstructures

# Lewisstructures - If the number of electrons needed equals...

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Lewis Structures: Lewis Structures represent covalent bonding using lines for bonding pairs and dots for lone pairs. The Players: Bonds – symbolized by 1 line between a pair of atoms for every 2 electrons shared between those atoms. Lone Electron Pairs – symbolized by a pair of dots for each unshared valence electron pair. Formal Charge – a charge shows a deviation from valence . Plus charge = not enough electrons Minus charge = too many electrons Writing Lewis Structures: 1. Start with proposed connectivity (skeleton). (put the atom that can form the most number of bonds in the center.) Ex. HCN H-C-N as proposed connectivity 2. Form bonds along these linkages 3. Assign each atom its quota of valence electrons H = 1, B = 3, C = 4, N = 5, O = 6, F = 7 4. Count the number of electrons needed to satisfy octet rule.
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Unformatted text preview: If the number of electrons needed equals the number remaining, go to 5. If fewer electrons remain, add one bond for every two additional electrons needed. 5. Assign unused electrons as lone pairs to satisfy the octet rule. Typical # of bonds formed by atoms in stable neutral molecules: 1 bond H, F, Cl, Br, I 2 bonds -O-, -S- 3 bonds N, B 4 bonds C You should be able to write the lewis structures for the following: HCl CH 4 C 2 H 4 H 2 O CCl 4 CH 2 O Br 2 NH 4 + HCN H 4 N 2 Ex: H 2 CO H C H O needs 6 e- to have octet needs 2 e- to have octet total electrons available: O = 6 C = 4 2 X H = 2 x 1 = 2 total = 12 e-This structure accounts for 6 e's add one bond because 2 more electrons are needed that are available. Assign the remaining 4 electrons as lone pairs around the oxygen. H C H O Correct Lewis Structure...
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