Exam 3, Fall 2004

MULTIPLE CHOICE. (2.5 pts. each) Choose the one alternative that best completes the
statement or answers the question.

1) What is the ground-state electron configuration of Se2-? 

A) [Ar]3d104s24p2 B) [Ar]3d104s24p6

C) [Ar]3d124s24p4 D) [Ar]3d104s24p4

2) Which of the following represents the change in electronic configuration that is associated with the first ionization energy of magnesium? 

A) [Ne]3s2 + e- Â [Ne]3s23p1 B) [Ne]3s13p1 Â [Ne]3s1 + e-

C) [Ne]3s2 Â [Ne]3s1 + e- D) [Ne]3s2 Â [Ne]3s13p1

3) Which element, indicated by letter on the periodic table above, has a 2+ ion with the electron configuration [Ar]3d10

A) A B) B C) C D) D

4) Which two ions have the same electron configuration in the ground state? 

A) Fe2+ and Fe3+ B) Rb+ and Cs+

C) Se2+ and I- D) Ba2+ and I-

The four spheres below represent Na+, Mg2+, F, and O2-, not necessarily in that order.

5) Which sphere most likely represents the F- ion? 

A) A B) B C) C D) D

6) Arrange the ions N3-, O2-, Mg2+, Na+, and F- in order of increasing ionic radius, starting with the smallest first. 

A) N3-, Mg2+, O2-, Na+, F-

B) N3-, O2-, F-, Na+, Mg2+

C) Mg2+, Na+, F-, O2-, N3-

D) N3-, O2-, Mg2+, F-, Na+

7) Of the following, which element has the highest first ionization energy? 

A) Na

B) Cl

C) P

D) Al

8) Which ionization process requires the most energy? 

A) Cl(g) Â Cl+(g) + e-

B) S+(g) Â S2+(g) + e-

C) S(g) Â S+(g) + e-

D) Cl+(g) Â Cl2+(g) + e-

9) Which of the above pictures best represents a solid ionic compound?  

A) picture (a)

B) picture (b)

C) picture (c)

D) picture (d)

10) Which electron affinity process would liberate the most energy? 

A) [He] 2s2 + e- Â [He] 2s2 2p1

B) [He] 2s2 2p2 + e- Â [He] 2s2 2p3

C) [He] 2s2 2p6 + e- Â [He] 2s2 2p6 3s1

D) [He] 2s2 2p3 + e- Â [He] 2s2 2p4

The following pictures represent alkali halide salts.

11) Which salt has the highest lattice energy? 

A) picture (a)

B) picture (b)

C) picture (c)

D) picture (d)

12) Which chemical process is associated with the lattice energy for sodium chloride? 

A) NaCl(g) Â Na+(g) + Cl-(g)

B) NaCl(s) Â Na+(g) + Cl-(g)

C) NaCl(s) + H2O(l) Â Na+(aq) + Cl-(aq)

D) Na(s) + 1/2 Cl2(g) Â NaCl(s)

13) Covalent bonding is a  ______

A) transfer of electrons.

B) gain of electrons.

C) loss of electrons.

D) sharing of electrons.

14) Which bond should have the highest bond dissociation energy? 

A) NhN

B) NN

C) NN

D) All three bonds should have about the same dissociation energy.

15) Which electrostatic forces hold atoms together in a molecule?

A) electron-nucleus forces

B) electron-electron forces

C) nucleus-nucleus forces

D) all three forces

16) Of the following elements, which has the highest electronegativity? 

A) Sc

B) S

C) P

D) As

17) The electronegativity is 2.1 for H and 1.8 for Si. Based on these electronegativities, SiH4 would be expected to  ______

A) have polar covalent bonds with a partial negative charges on the H atoms.

B) be ionic and contain H+ ions.

C) have polar covalent bonds with a partial positive charges on the H atoms.

D) be ionic and contain H- ions.

18) The compound ICl contains ________

A) polar covalent bonds, with partial negative charges on the Cl atoms.

B) ionic bonds.

C) nonpolar covalent bonds.

D) polar covalent bonds, with partial negative charges on the I atoms.

19) Which is the most acceptable electron dot structure for N2H2? 

A)

B)

C)

D)

20) How many lone pairs of electrons are on the P atom in PF3? 

A) 3 B) 1 C) 2 D) 0

21) Which molecule contains a triple bond? 

A) H2CO B) HCN C) O3 D) F2

22) Which element can expand its valence shell to accommodate more than eight electrons? 

A) He

B) C

C) P

D) O

23) Which of the following are allowed resonance forms of NCS-?

A) only III

B) I and III

C) only I

D) only II

24) Assign formal charges to each atom in the resonance form for SOCl2 given below.

24) ______

A) -1 for Cl, -2 for S, and -2 for O

B) -1 for Cl, +4 for S, and -2 for O

C) 0 for Cl, +1 for S, and -1 for O

D) 0 for Cl, 0 for S, and 0 for O

25) What geometric arrangement of charge clouds is expected for an atom that has four charge clouds? 

A) trigonal bipyramidal

B) tetrahedral

C) square planar

D) octahedral

26) What is the molecular geometry of BrF4-? 

A) square planar

B) tetrahedral

C) seesaw

D) square pyramidal

27) Identify the set of hybrid orbitals shown below.

A) sp

B) sp2

C) sp3

D) sp3d

28) Which orbital hybridization is associated with a tetrahedral charge cloud arrangement? 

A) sp3

B) sp3d2

C) sp2

D) sp

29) Which of the following would be expected to have sp2 hybridization on atom A?

A) II

B) I and III

C) I and IV

D) I, II, and III

30) The MO diagram below is appropriate for B2. Based on this diagram, B2

A) has a bond order of two and is paramagnetic.

B) has a bond order of one and is diamagnetic.

C) has a bond order of two and is diamagnetic.

D) has a bond order of one and is paramagnetic.

31) The paramagnetism (presence of unpaired electrons) of O2 is explained by  ______

A) molecular orbital theory.

B) coordinate covalent bonding.

C) valence bond theory.

D) resonance.

32) Which drawing represents a s bonding molecular orbital for a homonuclear diatomic molecule? 

A)

 

B)

 

C)

 

D)

 

33)  Write all Lewis Structures (resonance forms) that describe N3-.  What is the molecular shape of this ion.

34)  Calculate the energy change for the formation of one mole of CaF2(s) from its elements in their standard states using the following information.

Ca(s)  +  F2(g)  -->  CaF2(s)                      ?

Ca(s)  -->  Ca(g)                                  179.3 kJ/mol
Ca(g)  -->  Ca+(g) + e-                        589.9 kJ/mol
Ca+(g)  -->  Ca+2(g)  + e-                   1145 kJ/mol
1/2 F2(g)  -->  F(g)                                 79.0 kJ/mol
F(g)  +  e-  -->  F-(g)                            -328.0 kJ/mol
CaF2(s)  -->  Ca2+(g)  +  2F-(g)          2630 kJ/mol

 

ANSWERS:

1) B

2) C

3) C

4) D

5) C

6) C

7) B

8) D

9) C

10) B

11) D

12) B

13) D

14) C

15) A

16) B

17) A

18) A

19) D

20) B

21) B

22) C

23) C

24) C

25) B

26) A

27) D

28) A

29) D

30) D

31) A

32) see text

33)  3 resonance forms:  one has two double bonds, two have a triple bond and a single bond; all are linear.

34)  -1214 kJ