Tarleton State University

Department of Chemistry, Geosciences, and Environmental Science

 

          Chemistry 1054-010                         College Chemistry                                  Fall 2009

 

                                                                     Exam 3-A-Key

Only questions pertaining to Chap 6 are answered!

 

Name:____________________________________________________

                             (Please write your name legibly)

 

Read all directions and questions carefully!!  This exam consists of two parts.  The first part consists of 10 multiple choice questions worth four points each for a total of 40 points.  The second part consists of five numerical problems worth either 10 or 15 points per question for a total of 60 points.  Show all your work necessary for the numerical problems as partial credit will be given for those problems.

 

Possibly Useful Constants

 

            For light:                                                         Speed of light:  c = 2.998 × 108 m/s

            Planck's Law:                                 Planck's constant:  h = 6.626 × 10-34 J·s

            DeBroglie's wavelength: 

            Bohr's model of hydrogen atom: 

 

 

 

Score

 

                                    Part 1 (40 points):_____________________

 

 

                                    Part 2 (60 points):_____________________

 

 

                                    Total (100 points):_____________________

 

 

Don’t forget to put your name on this test!

 

Good Luck!!

Part 1

 

Multiple Choice

 

Please indicate the answer to each question by putting your choice in the space provided.  There is only one correct answer for each question.  There will be 10 multiple choice questions worth 4 points each.

 

1.  A photon with which one of the following wavelengths will have the highest energy?

      (a)  1.0 m                                                                     (c)  1.0 cm

      (b)  1.0 mm                                                                  (d)  1.0 mm

                  (e)  All of these photons will have equal energies.

 

Answer:  D

The shortest wavelength has the highest energy (Planck’s Law)

 

2.  Which quantum number is associated with the shape of the region in which the electron is likely to be found?

      (a)  n                                                                            (c)  ml

      (b)  l                                                                             (d)  ms

 

Answer:  B

 

3.  How many orbitals are there in an f subshell?

      (a)  1                                                                            (c)  5

      (b)  3                                                                            (d)  7

 

Answer:  D

 

4.  Based solely on their position in the periodic table, which of the following atoms has the smallest atomic radius?

      (a)  N                                                                           (c)  Cl

      (b)  O                                                                           (d)  F

 

                                                                                                                                    Answer__________

 

5.  Which of the following is not a metallic property?

      (a)  good electrical conductivity                                 (c)  tendency to lose electrons to from cations

      (b)  low ionization energies                                         (d)  acidic oxides

 

                                                                                                                                    Answer__________

 

6.  Sodium reacts with water to form:

      (a)  sodium oxide and hydrogen gas                           (c)  sodium hydride and oxygen gas

      (b)  sodium hydroxide and hydrogen gas                   (d)  sodium peroxide and hydrogen gas

 

                                                                                                                                    Answer__________

 

7.  Which of the following ions will have the smallest ionic radius?

      (a)  Na+                                                                        (c)  Al3+

      (b)  F¯                                                                         (d)  O2-

                                                                                                                                    Answer__________

 

8.  Which of the following atoms has the highest electronegativity?

      (a)  P                                                                            (c)  N

      (b)  O                                                                           (d)  S

 

                                                                                                                                    Answer__________

 

9.  Which one of the following bonds is the longest?

      (a)  triple                                                                      (c)  single

      (b)  double                                                                   (d)  all of these bonds have equal lengths.

 

 

                                                                                                                                    Answer__________

 

10.  Which of the following electron configurations violates Hund’s Rule?

 

Answer:   C

Hund’s rule states that when you are filling degenerate orbitals (such as 2p subshell) the electrons are filled singly each with the same spin.  Answer C has two electrons paired up before all the orbitals in the 2p subshell are singly occupied.

 

Part 2

 

Numerical Problems

 

Solve the following problems, keeping track of significant figures where applicable.  Please show all the work necessary to obtain your answer in order to receive partial credit for possibly wrong answers.  Generally, full credit will not be given for the correct answer without any of the work performed to obtain the answer being shown on the paper.  Each question is worth either 10 or 15 points.

 

11.  (10 points)  What is the frequency and energy of a photon of light with wavelength equal to 6.89 × 10-9 m?

 

Calculate the frequency: 

 

Calculate the energy:  E = hn = (6.626 × 10-34 J s)(4.35 ×1016 1/s) = 2.88 × 10-17 J

Or


12.  (15 points)  Write the ground state electron configurations and the number of unpaired electrons for the following atoms or ions.

 

(a)  P   1s22s22p63s23p3   or [Ne] 3s23p3

 

 

 

(b)  Mn  1s22s22p63s23p64s23d5  or [Ar] 4s23d5

 

 

 

The electron configurations of ions is covered in Chap 7 not Chap 6.
 
(c)  Se2-  1s22s22p63s23p64s23d104p6  or [Ar] 4s23d104p6

 

 

 

(d)  Fe2+  1s22s22p63s23p63d6  or [Ar]3d6

 

 

 

(e)  Cu  1s22s22p63s23p64s13d10 or [Ar]4s13d10

 

 

13.  (10 points)  Which of the following sets of 3 quantum numbers is not allowed?  Indicate the sets that are not allowed by circling the quantum number that is not within its allowed range.  For the allowed sets, write the name of the orbital associated with that set of quantum numbers.

 

(a)  n = 4    l = 4  ml = –2    This is not allowed because the l number is too large.  It can only go up to 3 for n = 4.

 

 

(b)  n = 3   l = 2   ml = –1  This is allowed.  It is a 3d orbital.

 

 

(c)  n = 2   l = 1  ml = 1  This is allowed.  It is a 2p orbital.

 

 

___ (d)  n = 6  l = 0  ml = 1  This is not allowed because the ml value is out of range.  For l = 0, ml can only have one allowed value of “0”.
14.  (10 points)  Predict the products of the following reactions and balance the reaction.

 

(a)  Li(s)  +  S(s)  ® ??

 

 

 

(b)  K(s)  +  H2O(l)  ® ??

 

 

 

 

(c)  CO2(g)  +  H2O(l)  ® ??

 

 

 

 

(d)  Al(s)  +  O2(g)  ® ??

 

 

15.  (15 points)  Write the most correct Lewis structure for the following species:

 

(a)  HNO2                                                                    (c)  BeCl2

 

 

 

 

 

 

 

 

 

(b)  TeF4                                                                      (d)  OF2

 

 

 

 

 

 

 

 

 

(e)  SO22-

 

 

(10 points extra credit, no partial credit)  Define 2 out of the following 3 terms.  Clearly note which items that you want graded.  If you answer all 3 items without clearly noting which terms you want graded then only the first two items will be graded. 

 

Electronegativity:

 

 

 

 

Degnerate orbitals:

 

 

 

 

Lattice energy: