• Nuclear processes, including fusion, fission, and radioactive decays of unstable nuclei, involve release or absorption of energy. The total number of neutrons plus protons does not change in any nuclear process. (9-12)
• Spontaneous radioactive decays follow a characteristic exponential decay law. Nuclear lifetimes allow radiometric dating to be used to determine the ages of rocks and other materials. (9-12)

• Uncontrolled systems always evolve toward more stable states—that is, toward more uniform energy distribution (e.g., water flows downhill, objects hotter than their surrounding environment cool down). (9-12)

• Patterns in rates of change and other numerical relationships can provide information about natural systems. (6-8)

• Algebraic thinking is used to examine scientific data and predict the effect of a change in one variable on another (e.g., linear growth vs. exponential growth). (9-12)

• In nuclear processes, atoms are not conserved, but the total number of protons plus neutrons is conserved. (9-12)

• 6-8: 3C/M4. Technology is largely responsible for the great revolutions in agriculture, manufacturing, sanitation and medicine, warfare, transportation, information processing, and communications that have radically changed how people live and work.
• 6-8: 3C/M5. New technologies increase some risks and decrease others. Some of the same technologies that have improved the length and quality of life for many people have also brought new risks.
• 9-12: 3C/H5. Human inventiveness has brought new risks as well as improvements to human existence.

• 6-8: 4D/M1a. All matter is made up of atoms, which are far too small to see directly through a microscope.
• 6-8: 4D/M1b. The atoms of any element are like other atoms of the same element, but are different from the atoms of other elements.
• 9-12: 4D/H3. Although neutrons have little effect on how an atom interacts with other atoms, the number of neutrons does affect the mass and stability of the nucleus. Isotopes of the same element have the same number of protons (and therefore of electrons) but differ in the number of neutrons.
• 9-12: 4D/H4. The nucleus of radioactive isotopes is unstable and spontaneously decays, emitting particles and/or wavelike radiation. It cannot be predicted exactly when, if ever, an unstable nucleus will decay, but a large group of identical nuclei decay at a predictable rate. This predictability of decay rate allows radioactivity to be used for estimating the age of materials that contain radioactive substances.

• 9-12: 4E/H6. Energy is released whenever the nuclei of very heavy atoms, such as uranium or plutonium, split into middleweight ones, or when very light nuclei, such as those of hydrogen and helium, combine into heavier ones. For a given quantity of a substance, the energy released in a nuclear reaction is very much greater than the energy given off in a chemical reaction.

• 9-12: 4G/H6. The nuclear forces that hold the protons and neutrons in the nucleus of an atom together are much stronger than the electric forces between the protons and electrons of the atom. That is why much greater amounts of energy are released from nuclear reactions than from chemical reactions.

• 6-8: 11D/M3. Natural phenomena often involve sizes, durations, and speeds that are extremely small or extremely large. These phenomena may be difficult to appreciate because they involve magnitudes far outside human experience.

Looking for content support in nuclear processes, or want to supplement your students' textbook? This is a chapter from a cost-free digital textbook, developed for non-scientists. This chapter deals with the atomic nucleus and radiation, nuclear energy, and uses of radioactive substances. It builds a foundation to understand the physical forces in the nucleus (electrostatic force and strong force), and explains how chemical reactions differ from nuclear reactions. Graphs and diagrams depict what happens in radioactive decay. The section on chemical nuclear equations is straightforward and comprehensible for non-scientists.

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