Lesson Notes By Weeks and Term v4 - SHS 2
NUCLEAR PHYSICS
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NUCLEAR PHYSICS
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Subject: Physics
Class: SHS 2
Term: 1st Term
Week: 1
Grade code: 1.4.2.LI.1
Strand code: 4
Sub-strand code: 2
Content standard code: 1.4.2.CS.1
Indicator code: 1.4.2.LI.1
Theme: ATOMIC AND NUCLEAR PH YSICS
Subtheme: NUCLEAR PHYSICS
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This lesson introduces the fascinating world of nuclear physics, focusing on the phenomenon of radioactivity. We will explore why some atomic nuclei are unstable and how they release energy to become stable. This is not just abstract science; radioactivity has profound impacts on our daily lives here in Ghana, from advanced medical treatments at Korle Bu Teaching Hospital to preserving our agricultural produce like yams and mangoes through irradiation. By understanding the fundamentals of radioactivity, we can better appreciate its applications and the necessary safety precautions.
A. The Unstable Nucleus: The Root of Radioactivity
Recall that an atom consists of a central nucleus (containing protons and neutrons) and electrons orbiting it. Atomic Number (Z): The number of protons. This defines the element. Mass Number (A): The total number of protons and neutrons (A = Z + N). Isotopes: Atoms of the same element (same Z) but with different numbers of neutrons (different N and A). For example, Carbon-12 (⁶C¹²) is stable, but Carbon-14 (⁶C¹⁴) is unstable.
The stability of a nucleus depends on the balance between its protons and neutrons. Repulsive Force: Protons are positively charged and repel each other strongly (electrostatic force). Attractive Force: The strong nuclear force is a very powerful but short-range force that holds protons and neutrons together.
An imbalance in the proton-to-neutron ratio can make the strong nuclear force insufficient to hold the nucleus together. This makes the nucleus unstable. To become stable, the nucleus must release excess energy and/or particles.