HW5 - Lin (cgl286) – Homework 5 – Lyon – (52370) 1...

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Unformatted text preview: Lin (cgl286) – Homework 5 – Lyon – (52370) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. This HW assignment is due Tuesday, March 3, by 11PM. 001 10.0 points Which of the following contains only covalent bonds? 1. CCl 4 correct 2. NaCl 3. Na 2 SO 4 4. NaOH 5. Ca(NO 3 ) 2 Explanation: Ionic bonding occurs between metals and non-metals while covalent bonding occurs among non-metals. The only answer choice that does not con- tain a metal is CCl 4 , which contains only covalent bonds. Polyatomic ions such as NO 1- 3 are held to- gether with covalent bonds. This polyatomic ion is connected to calcium through ionic bonding, so calcium nitrate would contain both ionic and covalent bonds. 002 10.0 points The Lewis dot structure for an isolated carbon atom has 1. four lone electrons. 2. one pair of electrons and three lone elec- trons. 3. two pairs of electrons and two lone elec- trons. 4. two pairs of electrons. 5. one pair of electrons and two lone elec- trons. correct Explanation: The first two electrons pair; they are from the 2 s orbital. The next two electrons are un- paired since each singly occupies a 2 p orbital. 003 10.0 points Determine the number of the valence electrons in an atom of the element N. 1. None of these 2. 8 valence electrons 3. 4 valence electrons 4. 5 valence electrons correct 5. 1 valence electron 6. 6 valence electrons 7. 2 valence electrons 8. 3 valence electrons 9. 7 valence electrons Explanation: The electron configuration for N is [He] 2 s 2 2 p 3 . Counting the outer-shell super- scripts, N has 5 valence electrons. 004 10.0 points Write the electron-dot notation for the ele- ment O. 1. None of these 2. b O 3. b b b b b b b O 4. b b O 5. b b b b b O 6. b b b b O Lin (cgl286) – Homework 5 – Lyon – (52370) 2 7. b b b O 8. b b b b b b b b O 9. b b b b b b O correct Explanation: According to its electron configuration (1 s 2 ), O has 2 valence electrons, so the electron-dot notation for O is b b b b b b O 005 10.0 points In a Lewis formula the dots represent 1. however many electrons are needed to satisfy the octet rule. 2. all the electrons in the atoms. 3. only the electrons that are being trans- ferred or shared. 4. the valence electrons in all the atoms. correct Explanation: 006 10.0 points How many unshared (non-bonded) pairs of electrons are in NF 3 ? 1. twenty 2. no pairs 3. three 4. two 5. four 6. thirteen 7. one 8. ten correct Explanation: The total number of valence electrons is N 1 × 5 e- = 5 e- P 3 × 7 e- = 21 e- 26 e- and the Lewis structure is N b b F b b b b b b F b b b b b b F b b b b b b 007 10.0 points The Lewis dot structure of H 3 O + has (7, 8, 9) total electrons and (2, 3, 4) shared (bonded) pairs....
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This note was uploaded on 10/26/2010 for the course CH 52370 taught by Professor Lyon during the Spring '09 term at University of Texas.

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HW5 - Lin (cgl286) – Homework 5 – Lyon – (52370) 1...

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