Ch. 8 & 9  bonds & VSEPR    test     [90 points]       AP Chem

For problems involving calculations, show your work in an organized manner, include any relevant equation (or formula and conversion factor(s)), put the proper units in your calculations / answer, and have the proper number of significant figures in your answer.              

Academic Honesty:   The answers on this test are my own and I am using only the allowed set of notes as described in the syllabus.  I have not discussed the test questions with anyone before or during the test nor have I seen the test questions prior to the exam.  If you violate any of the preceding items or do not sign, your semester grade is a F.

                                                                                                Signature:  ___________________

1.  Draw 3 valid Lewis structures of SiO₂ , then identify the “best” Lewis structure based upon formal charges (show the values of the formal charges next to the atom & state reason(s) to delete a choice).  [15 points]

2.  fill-in the below table  [20 points]

# bonding pair of e-	# nonbonding pair of e-	Bond angle	Name of shape of molecule	Sketch shape of molecule
3	2
	1	120°
			Square planar
	0	90° & 120°

3.  In regards to SeCl₄ ,   [20 points]

a. draw its Lewis structure

b. sketch the molecule

c. what is / are the bond angles in the molecule ?

d. what is the name of the shape of the molecule ?

e. is it a polar or nonpolar compound ? Justify your answer.

4. Using valence bond theory, describe all of the bonds associated with the carbon bound to oxygen in an aldehyde containing a methyl group.  If any hybrid orbital(s) is / are needed, then explain why it is needed and describe its formation.  [15 points]

5.  Describe the basis of the covalent bond.  [10 points]

6.  old topic [10 points]

Draw the condensed structural formula of 3 isomers of pentane.

- - - - - - - - - - -

Ch. 8 & 9  bonds & VSEPR    retest  [90 points]                                           AP Chem

1.  What is the “best” Lewis structure(s) of PCS ^- ?  Justify your answer.  [15 points]

2.  What is compound, H₂ O versus NH₃ , has the larger bond angle ?  Justify your answer.  [10 points]

3.  Describe valence bond theory.  [10 points]

4.  Why can OCl₄ not exist, while SCl₄ could exist ?  [10 points]

5.  What is the relative size of the sodium atom versus the sodium cation ?  Justify your answer.  [10 points]

6.  If there are hybrid orbitals in H – C ≡ N, then explain why it is needed and describe its formation.  Use valence bond theory to describe the bonds in this compound.  [15 points]

7.  fill-in the below table.  [20 points]

# bonding pair of e-	# nonbonding pair of e-	Bond angle	Name of shape of molecule	Sketch shape of molecule
3	2
	1	120°
			Square planar
	0	90° & 120°