The Mendeleev Lab of 1869

Adapted from Holt Chemistry: Visualizing Matter, 2000

 

Problem:

 

 Use your knowledge of the periodic table to determine the identity of each of the nine unknown elements in this activity.

 

q       The unknown elements are from the following groups in the periodic table.   Each group listed below contains at least one unknown.

 

1          2          11        13        14        17        18

 

q       None of the known elements serve as one of the nine unknown elements.

q       No radioactive elements are used during this experiment.  The relevant radioactive elements include Fr, Ra, At, and Rn.

q       You may not use your textbook or other reference materials.  You have been provided with enough information to determine each of the unknown elements.

 

Procedure: 

 

1.      Inspect the properties of the known elements.

2.      Arrange the cards of the known elements in a crude representation of the periodic table. 

3.      Once the known elements are in place, inspect the properties of the unknowns to see where their properties would best "fit" the trends of the elements of each group.

4.      In your data table, assign the proper element name to each of the unknowns.  Record the symbol for each of the "unknowns" in your data table.

 

Data Table:

 

Be sure to make your data table so that you have enough space for all your unknown elements.

 

Conclusion:

 

Summarize your group's reasoning for assignment of each unknown.  Explain in a few sentences exactly how you predicted the identity of the unknowns.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Li

 

Physical State                  solid

Density                             0.534 g/cm3

Hardness                          soft, claylike

Conductivity                      good

Solubility (H2O)                 reacts with water

Melting Point                    180oC

Color                                 silver

Cl2

 

Physical State                  gas

Density                             0.00321 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 slight

Melting Point                    -101oC

Color                                 greenish yellow

 

 

Ag

 

Physical State                  solid

Density                             10.50 g/cm3

Hardness                          somewhat soft

Conductivity                      excellent

Solubility (H2O)                 none

Melting Point                    961oC

Color                                 silver

He

 

Physical State                  gas

Density                             0.00018 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 none

Melting Point                    -272oC

Color                                 colorless

 

Cu

 

Physical State                  solid

Density                             8.96 g/cm3

Hardness                          somewhat soft

Conductivity                      excellent

Solubility (H2O)                 none

Melting Point                    1803oC

Color                                

Na

 

Physical State                  solid

Density                             0.971 g/cm3

Hardness                          soft, claylike

Conductivity                      good

Solubility (H2O)                 reacts rapidly

Melting Point                    98oC

Color                                 silver

 

 

C

 

Physical State                  solid

Density                             2.10 g/cm3

Hardness                          soft, yet brittle

Conductivity                      good

Solubility (H2O)                 negligible

Melting Point                    3550oC

Color                                 black

Ca

 

Physical State                  solid

Density                             1.57 g/cm3

Hardness                          medium

Conductivity                      good

Solubility (H2O)                 reacts

Melting Point                    845oC

Color                                 silvery white

 

Unknown #8

 

Physical State                  solid

Density                             1.74 g/cm3

Hardness                          medium

Conductivity                      good

Solubility (H2O)                 reacts slowly

Melting Point                    651oC

Color                                 silvery white

Unknown #9

 

Physical State                  solid

Density                             11.85 g/cm3

Hardness                          very soft

Conductivity                      medium

Solubility (H2O)                 none

Melting Point                    303oC

Color                                 silvery white

 

Be

 

Physical State                  solid

Density                             1.85 g/cm3

Hardness                          brittle

Conductivity                      excellent

Solubility (H2O)                 none

Melting Point                    1287oC

Color                                 gray

Sn

 

Physical State                  solid

Density                             7.31 g/cm3

Hardness                          somewhat soft

Conductivity                      good

Solubility (H2O)                 none

Melting Point                    232oC

Color                                 silver

 

Ne

 

Physical State                  gas

Density                             0.00090 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 none

Melting Point                    -249oC

Color                                 colorless

Br2

 

Physical State                  gas

Density                             3.12 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 negligible

Melting Point                    -7.2oC

Color                                 reddish brown

 

 

K

 

Physical State                  solid

Density                             0.86 g/cm3

Hardness                          soft, claylike

Conductivity                      good

Solubility (H2O)                 reacts rapidly

Melting Point                    63oC

Color                                 silver

Ba

 

Physical State                  solid

Density                             3.6 g/cm3

Hardness                          soft

Conductivity                      good

Solubility (H2O)                 reacts strongly

Melting Point                    710oC

Color                                 silvery white

 

Xe

 

Physical State                  gas

Density                             0.00585 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 none

Melting Point                    -119.9oC

Color                                 colorless

In

 

Physical State                  solid

Density                             7.31 g/cm3

Hardness                          very soft

Conductivity                      medium

Solubility (H2O)                 none

Melting Point                    157oC

Color                                 silvery white

 

I2

 

Physical State                  solid

Density                             4.93 g/cm3

Hardness                          soft

Conductivity                      very poor

Solubility (H2O)                 negligible

Melting Point                    113.5oC

Color                                 bluish-black

Pb

 

Physical State                  solid

Density                             11.35 g/cm3

Hardness                          somewhat soft

Conductivity                      poor

Solubility (H2O)                 none

Melting Point                    327.5oC

Color                                 gray

Ar

 

Physical State                  gas

Density                             0.00178 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 none

Melting Point                    -189.2oC

Color                                 colorless

Ga

 

Physical State                  solid

Density                             5.904 g/cm3

Hardness                          soft

Conductivity                      medium

Solubility (H2O)                 none

Melting Point                    30oC

Color                                 silvery

 

Cs

 

Physical State                  solid

Density                             1.87 g/cm3

Hardness                          soft

Conductivity                      good

Solubility (H2O)                 reacts violently

Melting Point                    29oC

Color                                 silvery white

Unknown #1

 

Physical State                  solid

Density                             2.33 g/cm3

Hardness                          brittle

Conductivity                      intermediate

Solubility (H2O)                 none

Melting Point                    1410oC

Color                                 gray

 

Unknown #2

 

Physical State                  gas

Density                             0.00170 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 slight

Melting Point                    -219.6oC

Color                                 pale yellow

Unknown #3

 

Physical State                  solid

Density                             1.53 g/cm3

Hardness                          soft

Conductivity                      good

Solubility (H2O)                 reacts violently

Melting Point                    39oC

Color                                 silvery white

 

 

Unknown #4

 

Physical State                  gas

Density                             0.00374 g/cm3

Hardness                          none

Conductivity                      very poor

Solubility (H2O)                 none

Melting Point                    -156.6oC

Color                                 colorless

Unknown #5

 

Physical State                  solid

Density                             19.3 g/cm3

Hardness                          soft

Conductivity                      excellent

Solubility (H2O)                 none

Melting Point                    1064oC

Color                                 gold

 

 

Unknown #6

 

Physical State                  solid

Density                             2.54 g/cm3

Hardness                          somewhat soft

Conductivity                      good

Solubility (H2O)                 reacts rapidly

Melting Point                    769oC

Color                                 silvery white

Unknown #7

 

Physical State                  solid

Density                             5.32 g/cm3

Hardness                          fairly brittle

Conductivity                      fair to poor

Solubility (H2O)                 none

Text Box: HomeMelting Point                    937oC

Color                                 gray