CO32- NH3 24 8 Step #1: Add up the number of 4 + 3(6) + 2 = 5 + 3(1) = valence electrons that should be (carbon has four and each (nitrogen has five; each included in the Lewis Structure. oxygen has six; add two for the hydrogen has one) -2 charge) Step #2: Draw the “skeleton structure” with the central atoms and the other atoms, each connected with a single bond. Add six more electron Step #3: dots to each atom the except central atom. Also, never add dots to hydrogen. (no change) Step #4: Any electrons 24 24 = 0 leftover electrons 8 6 = 2 leftover “leftover” – – are placed on the central atom. electrons; placed around Find the number of leftovers by nitrogen taking the total from Step #1 and subtracting the number of electrons pictured in Step #3. (no change) Step #5: If the central atom has 8, then you are done. If not, then (no change) move two electrons from a different atom to make a multiple bond. Keep making multiple bonds until the central atom has 8 electrons. Critical Thinking Questions Write the Lewis Structure for nitrate, NO3-1. Hint: when you are done it should look very similar to CO32- in the table above. Draw the Lewis Structure for SO2. ChemQuest 24 Name: ____________________________
CO32- NH3 Step #1: Add up the number of valence electrons that should be included in the Lewis Structure. 4 + 3(6) + 2 = 24 (carbon has four and each oxygen has six; add two for the -2 charge) 5 + 3(1) = 8 (nitrogen has five; each hydrogen has one) Step #2: Draw the “skeleton structure” with the central atoms and the other atoms, each connected with a single bond. Step #3: Add six more electron dots to each atom except the central atom. Also, never add dots to hydrogen. (no change) Step #4: Any “leftover” electrons are placed on the central atom. Find the number of leftovers by taking the total from Step #1 and subtracting the number of electrons pictured in Step #3. 24 – 24 = 0 leftover electrons (no change) 8 – 6 = 2 leftover electrons; placed around nitrogen Step #5: If the central atom has 8, then you are done. If not, then move two electrons from a different atom to make a multiple bond. Keep making multiple bonds until the central atom has 8 electrons. (no change) Critical Thinking Questions Write the Lewis Structure for nitrate, NO3-1. Hint: when you are done it should look very similar to CO32- in the table above. Draw the Lewis Structure for SO2. ChemQuest 24 Name: ____________________________
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