Radioactive Decay: Alpha Decay

Introduction

• Alpha decay is one of the forms of radioactive decay, in which an unstable atomic nucleus emits an alpha particle.
• An alpha particle consists of two protons and two neutrons and is equivalent to a helium nucleus (He⁴⁺).

Alpha Decay Process

• During alpha decay, an unstable atomic nucleus ejects an alpha particle.
• The ejection of an alpha particle causes changes in the atomic structure of the parent nucleus.

Atomic Structure Changes

• Mass Number Change: The mass number (A) of the parent nucleus decreases by four units (4) after alpha decay.
• Atomic Number Change: The atomic number (Z) of the parent nucleus decreases by two units (2) after alpha decay.

Chemical Nomenclature

• Alpha particles are often represented with the chemical symbol He⁴⁺ to indicate their composition.
• It is important to note that alpha particles do not contain electrons and are distinct from helium atoms.

Example: Alpha Decay of Radon-219

• Radon-219 (²¹⁹Rn) undergoes alpha decay to become polonium-215 (²¹⁵Po).
• In this process, the mass number of radon-219 decreases by four units, and its atomic number decreases by two units.

Alpha Decay Equation

• The alpha decay of radon-219 into polonium-215 can be represented by the equation:
  • ²¹⁹Rn → ²¹⁵Po + He⁴⁺

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Radioactive Decay: Alpha Decay

Summary

• Alpha decay is a type of radioactive decay where an unstable nucleus emits an alpha particle (He²⁺).
• During alpha decay, the parent nucleus experiences a decrease of four units in its mass number (A) and a decrease of two units in its atomic number (Z).
• Alpha decay is an important process in understanding the behaviour of certain radioactive isotopes.