BackBeta Decay and Nuclear Equations in GOB Chemistry
Study Guide - Smart Notes
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Beta Decay
Definition and Process
Beta (β) decay is a type of radioactive decay that occurs when an unstable atomic nucleus emits a beta particle. This process changes the identity of the element by converting a neutron into a proton or vice versa, resulting in the emission of an electron or positron.
Beta particle: A high-energy, high-speed electron or positron emitted from the nucleus during radioactive decay.
Symbol for beta particle:
Example of beta decay:
Mercury-201 undergoes beta decay:
Properties of Beta Particles
Size: Beta particles are smaller than alpha particles.
Ionizing Power: Beta particles have a lower ionizing power compared to alpha particles, making them less damaging to biological cells.
Penetrating Power: Beta particles have more penetrating power than alpha particles and can be stopped by a sheet of metal or a large block of wood.
Writing Nuclear Equations for Beta Emission
Balanced Nuclear Equations
When writing nuclear equations for beta emission, it is important to balance both the atomic number and the mass number. The emission of a beta particle increases the atomic number by one while the mass number remains unchanged.
General form:
Examples
Magnesium-25: Explanation: Magnesium-25 emits a beta particle and becomes Aluminum-25.
Ruthenium-102: Explanation: Ruthenium-102 emits a beta particle and becomes Rhodium-102.
Counting Alpha and Beta Decays
Example Problem
Given: Pb-208 is formed from Th-232. How many alpha and beta decays have occurred?
Number of Alpha Decays | Number of Beta Decays |
|---|---|
6 | 4 |
Explanation: The transformation from Thorium-232 to Lead-208 involves a series of alpha and beta decays. Each alpha decay reduces the mass number by 4 and the atomic number by 2, while each beta decay increases the atomic number by 1 without changing the mass number.
Calculation: Th-232 () to Pb-208 ():
Alpha decay: emission
Beta decay: emission
Answer: 6 alpha decays and 4 beta decays.
