Lesson Notes By Weeks and Term v4 - SHS 1

Lesson Video

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Performance objectives

• Define key terms like nuclear reactions, isotopes, and radioactivity.
• Balance basic nuclear reactions involving alpha and beta decay.
• Explain the significance of balancing nuclear reactions.
• Solve problems involving nuclear reactions.

Lesson summary

This lesson introduces the fundamental principles of nuclear reactions, focusing on how to balance them. We will explore the idea that while chemical reactions involve electrons, nuclear reactions involve changes within the atomic nucleus itself, releasing vast amounts of energy. Understanding this is crucial not only for physics but also for appreciating modern technologies that affect our lives in Ghana, from medical treatments at Korle Bu Teaching Hospital to food preservation techniques used by the Ghana Atomic Energy Commission (GAEC) to help our farmers.

Lesson notes

A. Review of the Atom and Introduction to the Nucleus Remember that an atom consists of a central nucleus surrounded by electrons. The nucleus contains protons (positive charge) and neutrons (no charge). Collectively, protons and neutrons are called nucleons. Atomic Number (Z): This is the number of protons in the nucleus. It defines the element. For example, any atom with 6 protons is Carbon. Any atom with 92 protons is Uranium. Mass Number (A): This is the total number of protons and neutrons in the nucleus (A = Z + number of neutrons). It tells us the mass of that specific nucleus. Nuclide: A specific type of atomic nucleus. For example, Carbon-12 and Carbon-14 are different nuclides of the same element (Carbon).

We represent a nuclide using the following notation: $$ {A}_{Z}X $$ Where: `X` is the chemical symbol of the element. `A` is the mass number (top-left). `Z` is the atomic number (bottom-left).

Example: Uranium-238 is an important nuclide found in nature. It has 92 protons and (238 - 92) = 146 neutrons. We write it as: $$ {238}_{92}U $$ B. Radioactivity and Common Particles Some nuclides are unstable. Their nucleus has an imbalanced ratio of protons to neutrons. To become stable, they spontaneously break down or "decay," releasing energy and particles. This process is called radioactivity.

In balancing nuclear reactions, we must be familiar with the particles involved: Alpha Particle (α): Composition: It is a Helium nucleus, containing 2 protons and 2 neutrons. Charge: +2 Symbol: `${4}_{2}He$` or `α` Beta Particle (β): Composition: It is a high-speed electron ejected from the nucleus when a neutron decays into a proton and an electron. Charge: -1 Symbol: `${0}_{-1}e$` or `β⁻` Neutron (n): Composition: One neutron. Charge: 0 Symbol: `${1}_{0}n$` Proton (p): Composition: One proton. Also a Hydrogen nucleus. Charge: +1 Symbol: `${1}_{1}H$` or `${1}_{1}p$` C. The Two Golden Rules for Balancing Nuclear Reactions Balancing nuclear equations is like a simple accounting puzzle. You must ensure that the totals on both sides of the reaction arrow (`→`) are equal. Conservation of Mass Number (A): The sum of the mass numbers of the reactants (left side) must equal the sum of the mass numbers of the products (right side). Conservation of Atomic Number (Z): The sum of the atomic numbers of the reactants (left side) must equal the sum of the atomic numbers of the products (right side). D. Worked Examples: Step-by-Step Balancing

Evaluation guide

• Balance basic nuclear reactions.
• Think pair share: Guide learners to balance nuclear reactions.
• conceptual
• understanding