National Science Content Standards for Physical Science -- Grades 9-12

From the National Research Council's Science Education Standards -- Chapter 6: Science Content Standards (Grades 9-12).

Physical Science

CONTENT STANDARD B: As a result of their activities in grades 9-12, all students should develop an understanding of

• Structure of atoms

• Structure and properties of matter

• Chemical reactions

• Motions and forces

• Conservation of energy and increase in disorder

• Interactions of energy and matter

RETURN TO TOP

STRUCTURE OF ATOMS

• Matter is made of minute particles called atoms, and atoms are composed of even smaller components. These components have measurable properties, such as mass and electrical charge. Each atom has a positively charged nucleus surrounded by negatively charged electrons. The electric force between the nucleus and electrons holds the atom together.
  • It's Elementary
    http://www.beyondbooks.com/psc92/1d.asp
    
  • Atoms and Their Structure
    http://www.beyondbooks.com/psc92/1e.asp
    
  • Molecules
    http://www.beyondbooks.com/psc92/1f.asp
    

• The atom's nucleus is composed of protons and neutrons, which are much more massive than electrons. When an element has atoms that differ in the number of neutrons, these atoms are called different isotopes of the element.
  • Atomic Properties
    http://www.beyondbooks.com/psc92/1g.asp
    

• The nuclear forces that hold the nucleus of an atom together, at nuclear distances, are usually stronger than the electric forces that would make it fly apart. Nuclear reactions convert a fraction of the mass of interacting particles into energy, and they can release much greater amounts of energy than atomic interactions. Fission is the splitting of a large nucleus into smaller pieces. Fusion is the joining of two nuclei at extremely high temperature and pressure, and is the process responsible for the energy of the sun and other stars.

• Radioactive isotopes are unstable and undergo spontaneous nuclear reactions, emitting particles and/or wavelike radiation. The decay of any one nucleus cannot be predicted, but a large group of identical nuclei decay at a predictable rate. This predictability can be used to estimate the age of materials that contain radioactive isotopes.

STRUCTURE AND PROPERTIES OF MATTER

• Atoms interact with one another by transferring or sharing electrons that are furthest from the nucleus. These outer electrons govern the chemical properties of the element.
  • Electron Basics
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  • More Electron Basics
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• An element is composed of a single type of atom. When elements are listed in order according to the number of protons (called the atomic number), repeating patterns of physical and chemical properties identify families of elements with similar properties. This "Periodic Table" is a consequence of the repeating pattern of outermost electrons and their permitted energies.
  • Patterns in Chemistry
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  • The Periodic Table
    http://www.beyondbooks.com/psc92/2a.asp
    
  • Periodic Trends
    http://www.beyondbooks.com/psc92/2e.asp
    
  • Periodic Table Games
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• Bonds between atoms are created when electrons are paired up by being transferred or shared. A substance composed of a single kind of atom is called an element. The atoms may be bonded together into molecules or crystalline solids. A compound is formed when two or more kinds of atoms bind together chemically.
  • Types of Chemical Bonding AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc92/3.asp
    

• The physical properties of compounds reflect the nature of the interactions among its molecules. These interactions are determined by the structure of the molecule, including the constituent atoms and the distances and angles between them.
  • Models and Shapes of Molecules AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc92/4.asp
    

• Solids, liquids, and gases differ in the distances and angles between molecules or atoms and therefore the energy that binds them together. In solids the structure is nearly rigid; in liquids molecules or atoms move around each other but do not move apart; and in gases molecules or atoms move almost independently of each other and are mostly far apart.
  • State and Phase Changes AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc92/9.asp
    
  • It's a Gas! AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc92/10.asp
    

• Carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, including synthetic polymers, oils, and the large molecules essential to life.

CHEMICAL REACTIONS

• Chemical reactions occur all around us, for example in health care, cooking, cosmetics, and automobiles. Complex chemical reactions involving carbon-based molecules take place constantly in every cell in our bodies.

• Chemical reactions may release or consume energy. Some reactions such as the burning of fossil fuels release large amounts of energy by losing heat and by emitting light. Light can initiate many chemical reactions such as photosynthesis and the evolution of urban smog.
  • Bond Energy
    http://www.beyondbooks.com/psc92/4b.asp
    

• A large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Radical reactions control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions.
  • Chemical Names and Formulas AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc92/5.asp
    
  • Chemical Equations and Reactions AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc92/7.asp
    
  • Reaction Types AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc92/8.asp
    

• Chemical reactions can take place in time periods ranging from the few femtoseconds (10^-15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales of billions of years. Reaction rates depend on how often the reacting atoms and molecules encounter one another, on the temperature, and on the properties--including shape--of the reacting species.

• Catalysts, such as metal surfaces, accelerate chemical reactions. Chemical reactions in living systems are catalyzed by protein molecules called enzymes.

MOTIONS AND FORCES

• Objects change their motion only when a net force is applied. Laws of motion are used to calculate precisely the effects of forces on the motion of objects. The magnitude of the change in motion can be calculated using the relationship F = ma, which is independent of the nature of the force. Whenever one object exerts force on another, a force equal in magnitude and opposite in direction is exerted on the first object.
  • Newton's Laws of Motion: Movin' On AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc91/4.asp
    
  • Momentum AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc91/6.asp
    

• Gravitation is a universal force that each mass exerts on any other mass. The strength of the gravitational attractive force between two masses is proportional to the masses and inversely proportional to the square of the distance between them.
  • Planetary Motion AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc91/9.asp
    

• The electric force is a universal force that exists between any two charged objects. Opposite charges attract while like charges repel. The strength of the force is proportional to the charges, and, as with gravitation, inversely proportional to the square of the distance between them.

• Between any two charged particles, electric force is vastly greater than the gravitational force. Most observable forces such as those exerted by a coiled spring or friction may be traced to electric forces acting between atoms and molecules.

• Electricity and magnetism are two aspects of a single electromagnetic force. Moving electric charges produce magnetic forces, and moving magnets produce electric forces. These effects help students to understand electricmotors and generators.

CONSERVATION OF ENERGY AND THE INCREASE IN DISORDER

• The total energy of the universe is constant. Energy can be transferred by collisions in chemical and nuclear reactions, by light waves and other radiations, and in many other ways. However, it can never be destroyed. As these transfers occur, the matter involved becomes steadily less ordered.

• All energy can be considered to be either kinetic energy, which is the energy of motion; potential energy, which depends on relative position; or energy contained by a field, such as electromagnetic waves.
  • Work, Energy, and Power AND ALL FOCUS TOPICS
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• Heat consists of random motion and the vibrations of atoms, molecules, and ions. The higher the temperature, the greater the atomic or molecular motion.

• Everything tends to become less organized and less orderly over time. Thus, in all energy transfers, the overall effectis that the energy is spread out uniformly. Examples are the transfer of energy from hotter to cooler objects by conduction, radiation, or convection and the warming of our surroundings when we burn fuels.

INTERACTIONS OF ENERGY AND MATTER

• Waves, including sound and seismic waves, waves on water, and light waves, have energy and can transfer energy when they interact with matter.
  • Pickin' Up Good Vibrations AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc91/10.asp
    
  • Surrounded by Sound AND ALL FOCUS TOPICS
    http://www.beyondbooks.com/psc91/11.asp
    

• Electromagnetic waves result when a charged object is accelerated or decelerated. Electromagnetic waves include radio waves (the longest wavelength), microwaves, infrared radiation (radiant heat), visible light, ultraviolet radiation, x-rays, and gamma rays. The energy of electromagnetic waves is carried in packets whose magnitude is inversely proportional to the wavelength.

• Each kind of atom or molecule can gain or lose energy only in particular discrete amounts and thus can absorb andemit light only at wavelengths corresponding to these amounts. These wavelengths can be used to identify the substance.

• In some materials, such as metals, electrons flow easily, whereas in insulating materials such as glass they can hardly flow at all. Semiconducting materials have intermediate behavior. At low temperatures some materials become superconductors and offer no resistance to the flow of electrons.