Chemistry Reference
In-Depth Information
Appendix A. Problems and Exercises
P6.1 You will find models in your chemistry collection at school: NaCl packing of
spheres, NaCl crystal structure and NaCl unit cell (see Fig.
6.3
). Give the
features of depiction of the three models. Discuss and compare the irrelevant
components of these models.
P6.2 The NaCl-structure can be described by the cubic face-centered lattice of
chloride ions where the octahedral holes are filled with sodium ions. Describe
the Li
2
O-structure and the ZnS-structure in a similar way and draw the
corresponding models (see Fig.
6.13
).
P6.3 Planning of chemistry lessons applies two levels: level 1 deals with pheno-
mena and lab experiences, level 2 with structural and mental models (see
Fig.
6.11
). Describe and draw your mental model of the diffusion of hydrogen
sulfide (H
2
S) in air on the basis of (a) the particle model of matter, (b)
Dalton's atomic model.
P6.4 Usually mental models are introduced in chemistry lessons from the particle
model, via Dalton's atomic model to the nucleus-shell model. Chose (a)
a substance and (b) a chemical reaction and make model drawings on the
basis of these three models. Discuss the differences in interpretation based on
those models.
P6.5 The chemical equilibrium can be illustrated with model experiments or
with every-day experiences. Give one example for each and establish connec-
tions to an example of a real chemical equilibrium.
Appendix B. Modeling Course: Structures of Metals and Salts
Material: 100 white cellulose balls
d
¼
30mm [
26
], 50 red cellulose balls
d
¼
12mm
[
26
], triangular wooden frame (
a
¼
17.5 cm), square wooden frame (
a
¼
15 cm),
modeling clay, glue, two equilateral ball-triangles (six balls with
d
¼
30 mm each).
1 sphere) are
structural models to describe the structure of many metal crystals (find drawing
models at the end of this sheet).
Structure the plural: Close-packing of spheres (1 metal atom
M 6.1: Fill up the triangular wooden frame with a closest layer of balls in the
triangular pattern. Put as many layers of balls on top as possible. Draw the
layers of balls.
M 6.2: The coordination number stands for the number of balls that touch one ball
in the middle of the packing. Find out the coordination number of one
sphere in the close-packing of spheres. Draw three layers of balls to
visualize this number.
M 6.3: Two different close-packings of spheres with the coordination number 12
are possible:
