Chemistry I - MAKEUP
Density - PERIODICITY
Name_______________________ Period______
Objectives:
1. To measure the mass and volume for silicon, tin, and lead and calculate their densities.
2. Use the density results for Si, Sn, and Pb to predict the density of germanium.
3. Calculate percent error of density of germanium.
Background:
Dmitri Mendeleev proposed his periodic law for the classification of elements in 1869-1871. After
observing trends in the properties of elements when they were arranged in order of atomic mass, Mendeleev
purposely left space for undiscovered elements. He not only predicted their existence, but predicted their
properties based on their proposed location on his periodic table.
At the time Mendeleev proposed his periodic law only 63 elements were known to exist. Their physical
and chemical properties had been studied and their atomic masses measured. Mendeleev arranged the
known elements in a calendar-like table of rows and columns in order of increasing atomic masses and
repeating chemical properties. It is at this point, however, that Mendeleev made a giant leap of discovery –
he suggested that there were gaps in his classification scheme because the elements were yet to be
discovered.
Among the Group IV elements in Mendeleev’s classification scheme, carbon appeared in the second
row, followed by silicon in the third row. Both tin and lead shared similar chemical properties with carbon
and silicon and were also known at this time. Because of their higher atomic masses, however, these metals
were placed in later rows of Mendeleev’s Group IV column of elements. In 1871, Mendeleev proposed that
there existed an as-yet-unknown element beneath silicon but above tin and lead in the Group IV elements.
He named the missing element eka-silicon and predicted its physical properties (atomic mass, melting point,
density, specific heat, and color) and chemical properties (ability to react with oxygen to form an oxide). In
1886 the element germanium was discovered by the German chemist Clemens Winkler. In his report of the
discovery, Winkler stated; “…There can be no longer any doubt that the new element is no other than the
eka-silicon prognosticated (predicted) fifteen years ago by Mendeleev.”
Within 15 years of Mendeleev’s prediction of the existence of missing elements, three of the “missing”
elements had been discovered and their properties were amazingly similar to those that Mendeleev had
predicted.
Hypothesis
 Germanium’s element symbol is ________________________
 Germanium is located in what group on the periodic table? ___________________
 In this group, Germanium is located above/below (circle one) Sn and Pb on the periodic table.
 I predict that density will increase/decrease (circle one) as you move down the periodic table.
 Therefore, I predict that the density of Germanium will be greater/smaller (circle one) that Sn and
Pb.
Safety
Silicon is flammable in powder form and is slightly toxic. Do not breathe or handle any fine silicon
powder remaining on the bottom of the container. Be sure to wash hands with soap and water after handling
the metals.
Materials:
Lead Shot, Pb, 35 g
Silicon Pieces, Si, 8 g
Tin Shot, Sn, 25 g
Electronic Balance
Small, Labeled Cups
Graduated Cylinder, 25 mL
Funnel
Wire Screen
Procedures:
Obtain Materials:
1. Graduated cylinder, wire screen, 1 small cup labeled Pb, 1 small cup labeled Si, 1 small cup labeled Sn, and a
funnel.
Measuring Mass & Volume:
2. The mass of the cup with the lid is ___3.35g____________. Record in data table as Initial Mass (g).
3. Obtain the cup labeled Si. (It has approximately 8 grams of silicon in it). Use the electronic balance to obtain
the combined mass of the cup and Si. Record in Data table as Final Mass (g) (record value with two after the
decimal and include unit of g for gram).
4. Fill the 25 mL graduated cylinder approximately half full of tap water. Measure the volume to two after the
decimal (EX: 15.51 mL) and record as Initial Volume (ml) in Data table.
5. Pour all of the Si from the cup into the graduated cylinder using the funnel.
6. Measure and record the new volume of the water (with the Si) in the graduated cylinder and record it as Final
Volume (ml) in the data table.
7. Once the measurements have been recorded for trial 1, use the wire screen to hold the Si in the graduated
cylinder while you drain the water down the drain. Do not allow any Si to go down the drain. You may have
to hold graduated cylinder upside down and gently tap to get any Si remaining in the graduated cylinder out.
8. Return the Si to the cup and replace lid.
9. Obtain the cup labeled Sn (approximately 25 g of Sn) and repeat steps 2-8.
10. Obtain the cup labeled Pb (approximately 35 g of Pb) and repeat steps 2-8.
11. Trial 1 should be complete using all three elements.
12. Complete TRIAL 2 using the same steps.
Clean up:
13. To clean up, wash hands and return materials to station. Each station will be checked before you may leave
the class.
Formulas:
14. Calculate the Mass of Solid = Final mass – Initial Mass. Record in data table.
15. Calculate the Volume of Solid = Final volume – Initial volume. Record in data table.
16. Calculate the Density by: d = m/v (g/mL) Record in data table.
17. Calculate Average Density by adding the two densities together and dividing by 2. Record in data table.
Figure 2
Final Volume – Initial Volume = Volume of Solid
Data Table:
Element Trial Station
#
Silicon
Si
Tin
Sn
Lead
Pb
Initial
Mass
(g)
Final
Mass
(g)
Mass
of
Solid
(g)
Initial
Final
Volume Density Average
Volume Volume of Solid (g/mL) Density
(mL)
(mL)
(mL)
(g/mL)
1
1
3.35g
11.76g
16.0ml
20.0ml
2
2
3.35g
11.64g
16.0ml
20.5ml
1
1
3.35g
29.51g
16.0ml
20.4ml
2
2
3.35g
28.68g
16.0ml
19.2ml
1
1
3.35g
39.41g
16.0ml
21.0ml
2
2
3.35g
39.18g
16.0ml
19.0ml
Calculations: Make sure to show all work for the mass, volume, & density for each trial for each solid.
Trial 1
Trial 2
Average
Density
Si
Sn
Pb
Mass:________________________
Mass:________________________
Volume:______________________
Volume:______________________
Density:______________________
Density:______________________
Mass:________________________
Mass:________________________
Volume:______________________
Volume:______________________
Density:______________________
Density:______________________
Mass:________________________
Mass:________________________
Volume:______________________
Volume:______________________
Density:______________________
Density:______________________
Graph:
 Make a BAR GRAPH of the Average Densities (g/ml) of the three elements from largest density to
the smallest (leave room to add germanium).
 Make it as big as possible – best fit! (Don’t forget your labels!)
 Using the graph, predict the density of Germanium. (add bar to the graph)
Analysis:
1. What was your predicted density for germanium using the bar graph: ______________________
2. Obtain true density for germanium from teacher and calculate your percent error using:
%error = | true – predicted | x 100
true
3. As you move down Group 14, what is the trend for density for the elements?
_________________________________________________________________________________
_________________________________________________________________________________
4. Refer to your periodic table information on the back page. Describe each trend for Group 14 as you
move down the group:
a. melting point - ______________________________________________________________
b. atomic mass - _______________________________________________________________
c. electron configuration - _______________________________________________________
d. electronegativity - ___________________________________________________________
e. atomic radius (size) - _________________________________________________________
5. When Mendeleev put the elements into his periodic table, he arranged them according to their
___________________ and _______________________. We currently order elements based on
their ________________________ and chemical properties.
6. Choose from words in parenthesis: Elements in the same (group/period) are very similar so if you
know the properties of a few of the elements in the same (group/period), you can infer the
properties of the rest of the elements in that (group/period)
Conclusion:
1. Did your experiment support/reject your hypothesis? (Include data )
2. Was your prediction of the density of Germanium accurate? Why? (Accuracy - percent error is less than 10% )
3. What could be some experimental errors that may have contributed to the inaccuracy of your
results? (Name at least 2)
Group 14 – Periodic Trends
Melting Point
Atomic Mass
Electron Configuration
Electronegativity
Atomic Radius
C
C
C
C
C
3550 C
12.01 amu
[He]2s 2p
2.5
0.910 x 10-10
Si
Si
Si
Si
Si
1.8
1.460 x 10-10
Ge
Ge
1.8
1.520 x 10-10
Sn
Sn
1.8
1.720 x 10-10
Pb
Pb
1.9
1.870 x 10-10
o
o
2
2
2
1410 C
28.09 amu
[Ne]3s 3p
Ge
Ge
Ge
937 C
72.59 amu
2
[Ar]4s 3d 4p
Sn
Sn
Sn
232 C
118.69 amu
2
Pb
Pb
o
o
o
327 C

2
207.20 amu
Density of Germanium (Ge) is 5.32g/ml
10
2
10
2
[Kr]5s 4d 5p
Pb
2
14
10
2
[Xe]6s 4f 5d 6p