Name:                                                                                                  Chem 9, Section:                                 

 

Lab Partner:                                                                                          Experiment Date:                                 

 

Flame Tests of Metal Cations

 

Experimental Data and Observations

 

Solution

Dominant Flame Color

Wavelength (nm)

LiCl

 

 

NaCl

 

 

KCl

 

 

CuCl2

 

 

BaCl2

 

 

CaCl2

 

 

 

Data Analysis

 

Using the wavelengths recorded above, calculate the corresponding frequencies and photon energies for the emitted radiation observed for each compound tested.  Record the results of your calculations in the table below.

 

Solution

Wavelength (m)

Frequency (s-1)

 

LiCl

 

 

 

NaCl

 

 

 

KCl

 

 

 

CuCl2

 

 

 

BaCl2

 

 

 

CaCl2

 

 

       

 

Show a set of sample calculations for LiCl only below.  Clearly show any equations you have used.

 

Wavelength (in m):

 

 

 

 

 

Frequency (in s-1):

 

 

 

 

 

Questions

 

1)   Complete the following paragraph by circling the correct responses:

 

In this experiment, the metal cations in the solutions were initially in the (ground, excited) state.  When placed in the flame, the metals then (absorbed, emitted) energy as (electricity, heat, EM radiation).  When this occurred, electrons made transitions from (low, high) energy levels to (low, high) energy levels.  The metals were then in the (ground, excited) state.  The electrons in these metals then made transitions from (low, high) energy levels to (low, high) energy levels, resulting in the (absorption, emission) of energy as (electricity, heat, EM radiation).

 

2)   What evidence is there that the colors observed in the flame tests are due to the metals, and not the nonmetals in the compounds tested?

 

 

 

 

 

3)   Which metal cation was observed to emit radiation with the longest wavelength?                                         

 

Compared to the other metals studied, did the radiation emitted by this metal cation (identified above) have

                 

the highest or lowest frequency?                                                                                 

                              

       

 

Exercise

 

In the Bohr Model of the atom, electrons occupy fixed orbits around the nucleus called energy levels.  However in the Quantum Mechanical Model of the atom, electrons occupy orbitals.  Orbitals are grouped by size and shape into shells and subshells (or, levels, and sublevels).  Electron configurations and orbital diagrams are used to show the arrangement of electrons in shells (levels), subshells (sublevels) and orbitals for specific atoms.  

 

Write complete electron configurations and abbreviated orbital diagrams for each of the elements given below.  Circle the valence electrons in your complete electron configurations.

 

Chlorine

 

complete configuration:                                                                                                                                     

 

abbreviated orbital diagram:

 

 

                                                                                                                                                                                                                                                                                                                                               

Tin

 

complete configuration:                                                                                                                                     

           

abbreviated orbital diagram:

 

 

 

Cobalt

 

complete configuration:                                                                                                                                     

 

abbreviated orbital diagram:

 

 

 

Selenium

 

complete configuration:                                                                                                                                     

 

abbreviated orbital diagram:

 

 

 

Boron

 

complete configuration:                                                                                                                                     

 

abbreviated orbital diagram:

 

 

 

Mercury

 

complete configuration:                                                                                                                                     

 

abbreviated orbital diagram:

 

 

 

Magnesium

 

complete configuration:                                                                                                                                     

 

abbreviated orbital diagram:

 

 

 

 

 

Additional Questions:  Do you expect the product formed during the combustion of magnesium in Test 6 (the ashy magnesium oxide) to weigh more than, less than, or the same as the original piece of magnesium?  Explain.

 

e.   The combustion of magnesium produces magnesium oxide, MgO.  Write the equation for the combustion of magnesium.

 

Word Equation: