The Nature of Science: Students should be aware that science
is both a way of knowing about the natural world and a body of knowledge,
that it is characterized by certain standards of analysis and peer
review, and that it is a distinctly human endeavor.
Types of Chemistry and Examples of What Chemists Do: Students
should know that there different branches of chemistry, that there
are many different type of chemists, and that chemists function
in research, teaching, and industry. Of interest would be chemists
in the food or cosmetic industry, those involved in mining operations,
those that study and create synthetic gems, those involved in materials
science, those that work with explosive substances, etc.
The Nature of Matter: Since chemistry is defined as the science
of matter, the nature of matter should be a starting point for the
class. Students should be aware that matter is anything that has
mass and occupies space. Obviously, the concepts of mass and space
should be considered in developing a sense of the nature of matter.
The nature of pure substances (elements and compounds), that they
are characterized by intrinsic and extrinsic physical properties,
and the differences between pure substances and mixtures would fall
into this category. Specific physical properties, how to determine
or measure them, and how to use them to identify or differentiate
substances would all be included int his topic
What models are and how they are used in chemistry: Since most
of what is "known" about the structure and behavior of
matter is based on the indirect measurement of "something"
that acts as invisible particles and since the description of this
behavior by chemists conforms to a model or models of what this
"something" appears to be, the nature of models and modeling
is actually integral to the understanding to both chemistry and
how a chemist views the world. I think a chemistry teacher should
emphasize what a model is, what it can and cannot do and how it
is used to explain the behavior of something that cannot be directly
seen. Practice in "black box" and indirect measurement
activities and in developing models is essential.
Phases and Physical Properties of Matter (gas, liquid, solid): Chemistry
students usually are able to list the phases of matter, can even
describe their characteristics, but rarely are able at the onset
to describe their behavior in terms of what is happening on the
"unseen" level. Here the particulate model of matter can
be introduced with an exploration of the physical properties of
the different phases, and a broader discussion of the Kinetic
Molecular Theory, a central concept in both chemistry and physics.
This theory underscores how energy affects matter and is used to
explain the behavior of gases, liquids, and solids.
History of Atomic Models: Chemistry students often assume that
the model of the atom with a nucleus containing neutrons and protons
and electrons moving around the outside is the "true"
and only concept of the atom, usually since it is taught as a fact
and not as a model. A history of the development of the modern atomic
model from the time of John Dalton, with an emphasis on the types
of observations used in the formation of each model, contributes
to an understanding of the nature of scientific inquiry, its dependence
on time and place, and the creativity involved. A model is only
as good as the data used to build it and the instruments used to
generate the data.
Atomic Structure (nucleus, protons, neutrons, electrons): The
current model of the structure of the atom, with specific details
about the nucleus, protons, neutrons, electrons, energy levels,
electron configuration, and the role of electrons in chemical reactivity
is the central, unifying idea in chemistry. The formation of ions
and isotopes would be part of this topic.
The Periodic Table (Development, Use, and Periodic Trends) :
The periodic table is a key tool and source of information in chemistry.
Knowledge about its development teaches about the nature of science.
A literate person, in science or otherwise, should at least recognize
the chart. A student of chemistry should know how to use the chart
to find an element by its symbol, determine the atomic number and
atomic mass, and recognize characteristics of chemical families,
understand and describe periodic trends, and predict reactivity
from position in the chart, and recognize that placement on the
chart is not random but based on atomic structure (electrons).
Chemical Symbols and Formulas: Chemistry has a specific language
based on symbols for the chemical elements. Students should know
the symbols for common elements, be able to find the symbols on
a periodic chart, and use them correctly to write the formulas for
elements and compounds. Knowledge of how ionic compounds are named
and the use of ionic charge to write the formulas is essential if
students are to be able to read and write chemical equations.
Chemical Bonding (types of bonds and role of electrons in bonding):
Differences between ionic and covalent bonds, types of covalent
bonds, and the nature of metallic bonds are key to understanding
the behavior of different substances. There are different ways to
model how the bonds form; I am most comfortable with the Lewis dot
method. But an understanding of the differences in the types of
bonds, their electrical nature, and how this affects their behavior
and reactivity are essential.
Chemical Properties of Matter, Characteristic Signs of Chemical
Changes, Types Chemical Reactions, and Factors Affecting Reactions:
Students should be able to recognize when a chemical change
is occurring or has occurred. Not all chemicals explode when they
react, even though this is what they most want to see and do. Students
should also be able to recognize the difference between a physical
and a chemical change. Chemical reactions are the heart of chemistry
and students should be able to differentiate between synthesis,
decomposition, and displacement reactions.
Chemical Equations (write, translate symbols, and balance):
This is the language in which chemistry is communicated. An understanding
of what the chemical equation represents and how it is used qualitatively
to describe a reaction and quantitatively to predict the masses
of reactants and products is central to chemical knowledge.
Mass, Moles, and Avogadro’s Number: Matter is measured in mass
and in moles. The mole is the basic quantitative unit used in chemistry.
It can be related to the particulate model of matter. Avogadro’s
number is a neat number anyway, even if it is too big to really
comprehend. But its use underscores the nature of the "invisibleness"
of atoms. Calculation of atomic mass and formula mass would be part
of this concept.
Mass Relations (stoichiometric relationships---calculation of theoretical
yield, limiting reactant, and percent yield): Since college
chemistry courses assume that entering freshmen know how to do these
kinds of problems, they need to be taught. This is probably the
hardest part of the chemistry course, for my students at least.
Acids and Bases: The mathematics of acids and bases is frequently
difficult for beginning chemistry students to understand let alone
master, but they should be aware of the hydrogen and hydroxide ion
differences between acids, bases and neutral substances, what the
pH scale reads, and how indicators are used to determine pH. This
can be taught using household substances, by real or simulated acid
rain studies, or by environmental monitoring studies.
Carbon Chemistry: An understanding of the special properties
of the carbon atom and its central role in organic substances is
essential since the people studying chemistry are constructed of
carbon-based molecules. I usually end the chemistry course with
simple organic nomenclature, which I treat as a problem-solving
game or puzzle. The students find this refreshingly easy after stoichiometry
and gas laws, but this is probably because by this time of the year
they actually have some understanding of chemistry. The nomenclature
exercises lead to discussions of nutrition and food testing lab
activities, followed by discussions of drug structure and effects.
Again, by this time of the year the students known the language
of chemistry and can "read" and understand structural
formulas that were incomprehensible at the beginning of the year.