Chemistry: Content Knowledge (0245)

The Praxis II Series Chemistry Content Knowledge exam is constructed to assess the ability of prospective teachers to teach high school chemistry. Administered over the course of two hours, this exam contains 100 multiple choice questions that are divided into seven areas as follows:

• 23 questions covering Periodicity and Reactivity; Chemical Reactions; Biochemistry and Organic Chemistry
• 16 questions covering Matter and Energy; Heat, Thermodynamics and Thermo chemistry
• 14 questions covering Nomenclature; The Mole, Chemical Bonding, and Geometry
• 14 questions covering Mathematics, Measurement, and Data Management; Laboratory Procedures and Safety
• 12 questions covering Solutions and Solubility; Acid/Base Chemistry
• 11 questions covering History and Nature of Science; Science, Technology and Social Perspectives
• 10 questions covering Atomic and Nuclear Structure

The questions in the category of Periodicity and Reactivity; Chemical Reactions; Biochemistry and Organic Chemistry cover patterns of periodicity in electron configurations, periodicity in association with kinds of bonds, chemical reactions, characteristics of atoms, organic chemistry and chemistry related to biology.

The category of Matter and Energy; Heat; Thermodynamics, and Thermochemistry will focus on the types, arrangement, characteristics, and preservation of matter and/or energy. This area will also cover measurement of temperature; the influence of thermal energy on matter; the conduction of thermal energy; laws of molecular kinetics, gases, and thermodynamics; and thermochemistry.

The Nomenclature category will test knowledge of the naming system of molecular and ionic compounds and the naming of organic compounds among functional groups. Questions will also cover the mole as part of the composition of chemicals, chemical formulas, chemical bonding, and molecular biology.

The questions in the area of Mathematics and will concentrate of measuring and interpreting data, and the area of Lab Procedures will cover the proper use of substances and tools used in laboratories, safety associated with the mixing of chemicals, and proper disposal of substances.

The category regarding solutions, acids and bases will cover content such as vocabulary, kinds of solutions, influences of solubility, concentration, and the chemistry of acids and bases.

The History and Nature of Science category will cover the scientific process, formulation of experiments, the history of science, and issues related to science and society.

The Atomic and Nuclear Structure questions include the structure of atoms, the arrangement of electrons, and nuclear reactions.

PRAXIS II Chemistry: Content Knowledge (0245) Practice Questions

1. Chemistry is the physical science that studies:

A. atoms
B. molecules
C. crystals
D. All of the above

2. Which of the following is not part of the steps used in a scientific method?

A. A question is posed.
B. A formula is created.
C. Previous test results are studied.
D. An experiment is conducted.

3. Which of the following is not a chemical term?

A. Cosine
B. Matter
C. Atom
D. Compound

4. The fundamental states of matter include:

A. solid
B. liquid
C. plasma
D. All of the above

5. Which of the following statements is false?

A. Energy is the capacity to do work.
B. Energy is associated with movement.
C. Energy cannot change forms.
D. Energy is a closed system.

Answer Key For Chemistry Content Knowledge

1. Answer: D

Chemistry grew out of the practice known as alchemy, a philosophical and spiritual discipline that investigated the possibility of transforming base metals into gold. Modern chemistry is the physical science that studies the composition, structure, properties and reactions of atoms, molecules, crystals, and other aggregate matter by themselves or in relationship to each other. It is sometimes called the "central science" because it connects the other natural sciences. Chemistry studies matter in relation to energy (the capacity to do work), entropy (the measurement of energy unable to do work), and the spontaneity of chemical reactions (the changing of matter into one or more substances).

Chemistry is divided into several disciplines based on the type of matter being studied:

• ORGANIC CHEMISTRY studies compounds that contain carbon. Note: Some carbon compounds are considered inorganic compounds.
• INORGANIC CHEMISTRY studies mineral compounds.
• BIOCHEMISTRY studies organisms capable of responding to stimuli, reproduction, and growth.
• PHYSICAL CHEMISTRY studies energy systems at the macro, molecular, and submolecular levels.
• ANALYTICAL CHEMISTRY studies matter and its chemical composition and structure.

2. Answer: B

Scientific Method is a set of procedures used to study natural phenomena. It provides guidelines with which to pose questions, analyze data, and reach conclusions. It is used to investigate events, gain knowledge, or correct earlier conclusions and integrate new information with previously learned data.

The steps may happen at the same time, in a different order, may be repeated during the course of the study, and should be applied with intelligence, imagination and creativity.

This is the sequence used most of the time:

1. A question is asked. It should be stated in specific language to focus the inquiry.
2. The subject is thoroughly researched. Previous test results are studied. It is important to understand what the earlier experiment(s) proved or disproved.
3. With information gleaned from researching the topic, a hypothesis is formed about a cause or effect of the event or its relationship to other occurrences.
4. An experiment is designed and conducted to test the hypothesis and gather information.
5. The resulting data is analyzed to determine if they support or refute the hypothesis.

3. Answer: A

MATTER: any substance that has mass and takes up space

ATOM: small particle with a positively charged core made of protons, neutrons, and electrons

NUCLEUS: the positively charged center of an atom

PROTON: subatomic particle with a positive electric charge that forms part of the nucleus

NEUTRON: a neutral (has no electric charge) subatomic particle that forms part of the nucleus

ELECTRON: subatomic particle with a negative electric charge that circles the nucleus

ELEMENT: made of only one atom; cannot be broken down further. All the elements are grouped by their atomic number on the Periodic Table.

COMPOUND: two or more elements joined together with a specific ratio of atoms that determines its structure and a particular system that composes its chemical properties

MOLECULE: smallest part of an element that contains all of the elements particular properties. Organisms, cytoplasm, and cell membranes are made of molecules.

4. Answer: D

Matter is any substance that has mass and takes up space. It is all the physical items in the universe: dirt, air, water, chairs, pencils, parsnips, and pumpkins. Matter is composed of atoms (small particles with a positively charged core made of protons, neutrons, and electrons) and molecules (the smallest part of an element that contains all of its particular properties).

Elements have only one atom and cannot be broken down further. One hundred and nine (109) elements have been identified so far. Elements combine to form compounds, which have a specific ratio of atoms. This determines its structure and defines the chemical properties of the substance.

The four fundamental states of matter are:

• SOLID: Molecules are packed tightly together with a definite shape and volume.
• LIQUID: Molecules have the ability to move and do not disperse readily.
• GAS: Molecules move very quickly, have low density, and are distributed uniformly.
• PLASMA is the substance that contains proteins, fats, and other molecules suspended in water. It makes up the living matter of plant and animal cells.

5. Answer: C

Energy is the capacity to do work or cause change. It is always associated with movement whether at the molecular, atomic, or subatomic level. Its companion is entropy, which is the measurement of the level of disorder, or of energy unable to do work. Energy can change forms but it cannot be created or destroyed. It is a closed system that remains constant. This Principle of Physics is known as the Conservation of Energy.

There are many forms of energy: light (electromagnetic radiation within a specific wavelength), heat (movement of atoms or molecules), electric (attraction and repulsion of electrons and protons), mechanical (related, produced, or dominated by physical force), and nuclear (the charged center of an atom) to name the most common. There are two types of energy: potential, which is energy that is stored and waiting to be used, and kinetic, which is energy that is currently being used.

There is another type of energy called dark energy; however, scientists are not entirely sure what dark energy is. It appears to be some sort of antigravity that is pushing the galaxies apart. More study is needed to explain this force and its function in the universe.