CHEM125-C                                                                                                  Fall, 2004

Hourly Exam # 3                                                                                             Dunnivant

 

Name (PRINTED) ____________________________________

 

There are 100 points.

 

The honor statement must be signed in order for your exam to be graded.

Closed book, closed Internet, closed notes, closed neighbor!

I have neither given nor received aid on this exam.  

                                                            Signature ________________________

 

NOTES:

-Show all work for partial credit.  

-Significant figures and units will be graded throughout the exam.

 

h = 6.63 x 10-34 J¥s

Avg.Õs # = 6.022 x 1023 particles/mol

c = 2.998 x 108 m/s

R = 1.097x107 m-1

 

  1. Essay question.  Type your answers on the computer!  Strict one-half page, single-spaced, 12 point font limit!

 

a)     (8pts)  Contrast the Bohr and Schrodinger concept of the electron orbitals in a hydrogen atom.  What are the differences?

b)    (7 pts) Explain how bioconcentration works using intermolecular forces and chemical reactivity. 

 


  1. a)  (7 pts)  List the seven forms of electromagnetic radiation in increasing order of energy.  Label which end (top or bottom) has the highest frequency.  Label which end (top or bottom) has the highest wavelength.

 

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b) (3 pts)  List the colors of visible light from highest energy to lowest energy.

 

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  1. (10 pts) A particular chemical bond has an energy of 435 kJ/mol.  What is the longest wavelength of light that will break this bond?

 

 


  1. (10 pts)  An electron in hydrogen jumps from a principle energy level of 1 to 6.  What is the energy input to the hydrogen to make the electron jump?

 


  1. (3 pts) Give the complete spectroscopic notation for cesium.

 

 

 

(1 pt) Give the Noble gas notation for cesium.

 

 

 

(1 pt)  Give the Noble gas notation for the cesium ion.

 

 

 

 

  1. (10 pts)  Using the Periodic Table below, in general, put

 

A Ò1Ó where the atomic size in the smallest

 

A Ò2Ó where the ionic size for cations is the greatest

 

A Ò3Ó where the effective nuclear force is the least

 

A Ò4Ó where the electronegativity is the greatest

 

A Ò5Ó where the electron ionization energy is the smallest

 

 

 

 

  1. (15 pts)  Draw the Lewis dot structure for OCN-  (C is the central atom), all three possible resonance structures, and using the formal charge calculation determine which resonance structure is the most likely.

    2.
  2. (15 pts)  Draw the Lewis Dot structures for the following chemicals and give (name) the electron geometry, molecular geometry, and the symbol of the hybridization of the central atom.

 

 

H2O

 

 

COCl2 (C is the central atom)

 

 

CO

 

9.  Sorry, but itÕs essay time again.  Explain how we get from s, p, and d orbital shapes to the 3-D molecular geometries of molecules that we discussed in class. Type your answers on the computer!  Strict one-half page, single-spaced, 12-point font limit not counting figures!  Use as many figures as you need.