L3 - Lewis Structures

Lewis StructuresWriting Lewis StructuresLewis structures arerepresentations of moleculesshowing all electrons, bondingand nonbonding.PCl 35 + 3(7) = 261. Find the sum ofvalence electrons of allatoms in the moleculefrom the groupnumber or electrondot structure.Writing Lewis StructuresKeep track ofthe electrons:26 − 6 = 202. Build a reasonableskeletal structure forthe molecule usingonly single bonds. The central atomshould be the leastelectronegativeelement that isn’thydrogen.Writing Lewis StructuresKeep track ofthe electrons:26 − 6 = 20• Things to consider whenbuilding primary skeleton: Oxygen never bonds to itself,except in O 2 and O 3 Carbon atoms are usuallybonded to each other In molecules containing both Hand O, hydrogen is usuallybonded to oxygen Carbons should always besaturated with hydrogens whenpossibleWriting Lewis StructuresWriting Lewis StructuresKeep track of theelectrons:26 − 6 = 20 − 18 = 23. Subtract the totalnumber ofelectrons used inthe primary bondsfrom the availablevalence electrons.4. Fill the octets of theouter atoms byadding unsharedpairsKeep track of the electrons:26 − 6 = 20 − 18 = 2 − 2 = 05. Fill the octet ofthe central atom.6. Check to see thatall atoms haveand octet andthat the correctnumber ofvalence electronswere used2