Identify each of the following as alpha decay, beta decay, positron emission, or gamma emission:
a. ¹²⁷₅₅Cs → ¹²⁷₅₄Xe + ⁰₊₁e

Verified step by step guidance

1. Step 1: Understand the problem. The question asks us to identify the type of nuclear decay occurring in the given reaction. The reaction shows the transformation of ¹²⁷₅₅Cs (Cesium-127) into ¹²⁷₅₄Xe (Xenon-127) and a particle represented as ⁰₊₁e.
2. Step 2: Analyze the particle emitted. The particle ⁰₊₁e has a mass number of 0 and a charge of +1. This is characteristic of a positron, which is the antimatter counterpart of an electron.
3. Step 3: Recall the definition of positron emission. Positron emission occurs when a proton in the nucleus is converted into a neutron, and a positron (⁰₊₁e) is emitted. This process decreases the atomic number by 1 while keeping the mass number unchanged.
4. Step 4: Verify the changes in the reaction. In the given reaction, the atomic number decreases from 55 (Cesium) to 54 (Xenon), while the mass number remains 127. This matches the characteristics of positron emission.
5. Step 5: Conclude the type of decay. Based on the analysis, the given reaction is an example of positron emission.

Key Concepts

Alpha Decay

Alpha decay is a type of radioactive decay in which an atomic nucleus emits an alpha particle, consisting of two protons and two neutrons. This process decreases the atomic number by two and the mass number by four, resulting in a new element. It typically occurs in heavy elements, such as uranium and radium, and is characterized by low penetration power.

Beta Decay

Beta decay is a form of radioactive decay where a neutron in an atomic nucleus is transformed into a proton, emitting a beta particle (an electron or positron) in the process. This increases the atomic number by one while keeping the mass number unchanged. It is common in isotopes that have an excess of neutrons, leading to a more stable configuration.

Positron Emission

Positron emission is a specific type of beta decay where a proton is converted into a neutron, resulting in the emission of a positron (the antimatter counterpart of an electron). This process decreases the atomic number by one while the mass number remains the same. It is often observed in isotopes that are proton-rich and helps in achieving nuclear stability.