Table 5.
Table 5. The contents of "Chemistry II".
Unit
|
|
Contents
|
Science of matter
|
(a)
|
Knowledge: atoms, molecules, ions, chemical formula, atomic weight, molecular weight, mole, chemical equations
|
(b)
|
Inquiry activity: experiment on the quantitative relationship
|
Atomic structure and periodic table
|
(a)
|
Knowledge: components of atom, atomic model and electron configuration, periodic table, periodic properties of elements, elements of alkali family, the halogens, transition elements
|
(b)
|
Inquiry activity: experiment on the properties of elements in a family, prediction of periodicity with the periodic table
|
Chemical bonding and compounds
|
(a)
|
Knowledge: ionic bond, covalent bond, metallic bond, bond polarity, molecular geometry, organic compounds
|
(b)
|
Inquiry activity: observation of properties of ionic and covalent compounds, experiment on properties and preparation of organic compounds
|
States of gases, matter and solution
|
(a)
|
Knowledge: ideal gas equation, diffusion, pressure of a gas mixture, liquid and solid, solution
|
(b)
|
Inquiry activity: measurement of molecular weight of gas, experiment on the properties of solution, preparation of standard solution
|
Chemical reaction
|
(a)
|
Knowledge: heat of reaction, reaction rate, chemical equilibrium, acids and bases, neutralization titration and pH, salts, oxidation number, chemical cell, electrolysis
|
(b)
|
Inquiry activity: observation of the shift in equilibrium, experiment on the neutralization titration of acids and bases, measurement of electromotive force of cell
|
Top of Page
3. Comparison among Textbooks
In Korea, the contents on atoms and atomic structure are not introduced in elementary school science courses. They first appear in the first unit of "Science" for 8th graders. The concept of the atom is introduced after the subunit of compounds and elements. The contents of the atomic model and compounds in the "Science" textbook published by Kyo-Hak publishing company, for example, can be summarized as follows: 1) Dalton's atomic model; 2) historical changes of atomic models; 3) atomic model and the law of conservation of mass; 4) the law of definite proportions; and 5) the law of multiple proportions. A sample page of the textbook on atoms and atomic structure is shown in Figure 1.
Figure 1
The contents covered in this page are summarized as follows.
According to Dalton's atomic model, atoms are not fundamentally changed in any chemical reactions. The number and the mass of atoms as well as the type of atoms remain unchanged, but their arrangements do change. Therefore, many materials may be used as atomic models to explain atoms. Examples are in Figure I-29. A magnesium atom may be represented by a small ball, a bolt, or a paper clip, and an oxygen atom may be represented by a big ball, a nut, or a clothespin. In explaining chemical bonding of atoms, it is convenient if the bolt and the nut are represented by the symbols B and N respectively. The example (b) in Figure I-29 can be symbolized as follows: B + N ----> BN. When B and N are combined to form the compound BN, compare the total weight of B and N and the total weight of compound BN. What will happen if real substances undergo chemical reactions? For examples, precipitates or gases are produced in some chemical reactions. Let's find the changes in mass in several chemical reactions.
In high school chemistry textbooks for science track students, atomic structure is introduced in the third unit "Atomic Structure and Periodic Table". For example, the "Chemistry II' textbook by Keum-Sung publishing company summarizes the concepts of atomic structure as follows: 1) electrons and their properties; 2) atomic nucleus model; 3) Bohr's atomic model; 4) atomic orbitals; 5) three-dimensional atomic model; 6) energy levels in an atomic orbital; and 7) the arrangement of electrons in an atom. A sample page of the textbook on atoms and atomic structure is shown in Figure 2.
Figure 2
Figure 1. A sample page on atoms and atomic structure in a junior high school science textbook.
Figure 2. A sample page on atoms and atomic structure in a high school science textbook.
The contents of this page are summarized as follows.
Based on the results of a study of the electron using a cathode-ray tube, Dalton's atomic model that the atom cannot be further divided was questioned. However, no valid model for the atomic structure was proposed before 1911. In 1911, Rutherford obtained the following results from experiments on the scattering of alpha particles. First, most alpha particles pass through a metal foil with a thickness of 4x10-5 cm undeflected. This means that most of the volume of an atom is relatively empty space. Second, one out of approximately 2x104 alpha particles which are positively charged and relatively massive undergoes deflection at an angle of more than 90 degrees. This means that each atom has a particle which is much heavier and positively charged in a small space. The particle is the atomic nucleus.
Top of Page
Do'stlaringiz bilan baham: |