Chemistry Reference
In-Depth Information
Oxygen (g)
Hydrogen (g)
+
Water vapour (g); exothermic
6 H
2
+
+
3 O
2
O
2
6 H
2
O
2 H
2
O
2 H
2
100
C)
Fig. 10.28 Model for regrouping of molecules in the hydrogen-oxygen reaction (
t
>
10.6 Summary of the Structure-oriented Approach
With the intention of formulating important goals of science education, 150
participants from the United States and other countries met; professors of
universities, teachers of colleges and high schools, journalists of well-known
publishers, and managers of big companies. They wanted “benchmarks” of what
students should know or be able to do in science, mathematics, and technology by
the end of grades 2, 5, 8, and 12. These grades are suggested as reasonable
checkpoints for estimating students progress toward goals of science literacy [
16
].
In Chap. 4 of the “AAAS-Benchmarks for Science Literacy,” they highlighted
the importance of understanding the structure of matter and Dalton's atomic model:
“The scientific understanding of atoms and molecules requires combining two
closely related ideas: all substances are composed of invisible particles, and all
substances are made up of a limited number of basic ingredients, or 'elements.'
These two merge into the idea that combining the particles of the basic ingredients
leads to millions of materials with different properties.
By the end of grade 8
,
students should know that all matter is made up of atoms, which are far too small to
see directly though a microscope. The atoms of any element are alike, but are
different from atoms of other elements. Atoms may stick together in well-defined
molecules or may be packed together in large arrays: different arrangements of
atoms into groups compose all substances.” [
16
]
The structure-oriented approach of chemistry is doing just that; teaching the
atoms and different arrangements of atoms for students in beginner classes of
chemistry, which may be grade 7 in some countries or grade 8 in other countries.
The novel idea is that of using “atoms
and ions
as basic particles of matter” in the
sense of Dalton's atomic model; the ions are given with their positive or negative
charge and presented in the periodic table as spheres with different diameters (see
Fig.
10.3
). From atoms and ions, all substances can be created mentally; metal
atoms “left and left in the periodic table” can arrange in crystals of pure metals or
alloys, nonmetal atoms “right and right in the periodic table” in molecules or atomic
lattices, ions “left and right in the periodic table” will arrange in ionic lattices and
