AQA GCSE HIGHER PHYSICS - Nuclear Equations for Radioactive Decay

AQA GCSE Higher Physics: Nuclear Equations for Radioactive Decay

This tutorial will guide you through understanding and writing nuclear equations for radioactive decay, focusing on alpha and beta decay.

Understanding Nuclear Equations

Nuclear equations represent the changes occurring within the nucleus of an atom during radioactive decay. They follow these key principles:

• Conservation of mass number (A): The total number of protons and neutrons (nucleons) must remain the same on both sides of the equation.
• Conservation of atomic number (Z): The total number of protons must remain the same on both sides of the equation.

Alpha Decay

Alpha decay involves the emission of an alpha particle, which is a helium nucleus containing two protons and two neutrons.

• General Equation:

Parent Nucleus  ? Daughter Nucleus  +  ??He

• Example:

²³???U ? ²³???Th  +  ??He

Explanation:

• Uranium-238 (²³???U) is the parent nucleus, and Thorium-234 (²³???Th) is the daughter nucleus.
• The alpha particle (??He) is emitted, carrying away two protons and two neutrons.
• Notice how the mass number (A) decreases by 4 (238 ? 234) and the atomic number (Z) decreases by 2 (92 ? 90), reflecting the loss of an alpha particle.

Beta Decay

Beta decay involves the emission of a beta particle, which is a high-energy electron (?¹?e) or a positron (¹?e).

• Beta-minus decay: A neutron in the nucleus decays into a proton, emitting an electron and an antineutrino.

  • General Equation: Parent Nucleus ? Daughter Nucleus + ?-?e + ??
  • Example: ¹??C ? ¹??N + ?-?e + ??

• Beta-plus decay: A proton in the nucleus decays into a neutron, emitting a positron and a neutrino.

  • General Equation: Parent Nucleus ? Daughter Nucleus + ??e + ?
  • Example: ¹¹?C ? ¹¹?B + ??e + ?

Explanation:

• Beta-minus decay: The mass number (A) remains the same, but the atomic number (Z) increases by 1.
• Beta-plus decay: The mass number (A) remains the same, but the atomic number (Z) decreases by 1.

Practice Writing Nuclear Equations:

1. Polonium-210 (²¹???Po) undergoes alpha decay. Write the nuclear equation.
2. Carbon-14 (¹??C) undergoes beta-minus decay. Write the nuclear equation.

Remember:

• Always balance the mass number (A) and atomic number (Z) on both sides of the equation.
• Use the appropriate symbols for the alpha particle (??He), beta particles (?-?e or ??e), and neutrino (?) or antineutrino (??).

By understanding these concepts and practicing writing nuclear equations, you will be able to confidently explain and predict the outcomes of radioactive decay processes.