# Geometries McCord Answers - hacopian(eh7969 H06 Geometries...

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hacopian (eh7969) – H06: Geometries – Mccord – (52385) 1 This print-out should have 24 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. 001 10.0 points Consider a 3-atom molecule A B A For which B has a total oF only Four valence elec- trons – enough to make two bonds. Predict the A-B-A bond angle. 1. 180 correct 2. 60 3. 120 4. 109.5 5. 90 Explanation: 002 10.0 points What is the shape oF COCl 2 ? 1. trigonal pyramidal 2. tetrahedral 3. trigonal planar correct 4. seesaw 5. T-shaped Explanation: There are three regions oF electron density (with no lone pairs) around the central atom: C Cl b Cl O b b 003 10.0 points Which oF the Following has bond angles slightly LESS than 120 ? 1. O 3 correct 2. I 3 3. SO 3 4. 2 5. NO 3 Explanation: While SO 3 and O 3 have three regions oF electron density around the central atom, only O 3 has a lone pair in one oF these regions. The lone pair repels the other bonds more, which makes their angle slightly less than 120 . 004 (part 1 oF 2) 10.0 points Draw the Lewis structure For NO 2 . How many single bonds, double bonds, triple bonds, and unshared pairs oF electrons are on the central atom, in that order? 1. 0; 0; 1; 1 2. 3; 0; 0; 1 3. 1; 0; 1; 0 4. 2; 0; 0; 2 5. 0; 2; 0; 0 6. 0; 1; 1; 0 7. None oF these 8. 1; 1; 0; 1 correct 9. 2; 1; 0; 0 10. 4; 0; 0; 0 Explanation: N has 5 valence electrons and O has 6 va- lence electron. The total number oF valence electrons in the ion (plus one to account For the ion’s negative charge) is

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hacopian (eh7969) – H06: Geometries – Mccord – (52385) 2 5 + (2 × 6) + 1 = 18 The Lewis structure for NO 2 can be found by connecting the oxygen atoms to nitrogen and placing eight electrons around each atom: b O b b b N b b O B and the central atom has one single bond, one double bond, and one unshared pair of electrons. 005 (part 2 of 2) 10.0 points Determine the molecular geometry of the ion NO 2 . 1. None of these 2. trigonal-pyramidal 3. trigonal-planar 4. bent or angular correct 5. linear 6. octahedral 7. trigonal-bipyramidal 8. tetrahedral Explanation: The central atom N has 2 bonding regions and 1 lone pair of electrons. The three areas of high electron density make the electronic geometry trigonal planar and the molecular geometry bent or angular: N
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## This note was uploaded on 06/06/2011 for the course CHEM 301 taught by Professor Wandelt during the Spring '08 term at University of Texas.

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Geometries McCord Answers - hacopian(eh7969 H06 Geometries...

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