Problem 139 - A Complete Resource Book in Chemistry for JEE Main

Question

\(\beta\) particle is emitted in a radioactive reaction when [2002] (a) a proton changes to neutron (b) a neutron changes to proton (c) a neutron changes to electron (d) an electron changes to neutron

Step-by-Step Solution

Answer

The correct answer is (b) a neutron changes to proton.

Step 1: Understanding the Problem

To solve the problem, we need to identify the correct process in which a beta particle is emitted during a radioactive reaction. A beta particle refers to a high-energy, high-speed electron or positron that is emitted from a nucleus.

Step 2: Identify the Process of Beta Decay

Beta decay occurs when a neutron is converted into a proton in the nucleus of an atom, which increases the atomic number by one while the mass number remains unchanged. During this process, a beta particle (electron) and an antineutrino are emitted.

Step 3: Match the Options to the Identified Process

With the understanding that beta decay involves a neutron changing into a proton, compare each option: - (a) a proton changes to neutron. This is incorrect for beta decay. - (b) a neutron changes to proton. This is correct for beta decay. - (c) a neutron changes to electron. This is incorrect since electrons are emitted, not formed. - (d) an electron changes to a neutron. This is not a typical process in nuclear reactions.

Step 4: Conclude the Solution

After analyzing the options, option (b) 'a neutron changes to a proton' matches the process of beta decay where a beta particle is emitted.

Key Concepts

Radioactive Reaction

In the realm of nuclear physics, a radioactive reaction involves the transformation of an unstable atomic nucleus into a more stable configuration, typically by emitting particles and energy. This process is known as radioactive decay. It's an intrinsic property of certain elements that are not stable, which results from an imbalance in the forces that hold the nucleus together. Over time, these nuclei release excess energy by emitting radiation, leading to a change in their composition. Some key aspects are:

• Radioactive reactions involve the emission of particles like alpha particles, beta particles, or gamma rays.
• These emissions help the nucleus achieve a more stable state.
• The reactions are spontaneous and do not require external energy.

Understanding radioactive reactions helps us comprehend how elements transform over time and is crucial in fields like nuclear medicine and radiometric dating.

Neutron to Proton Conversion

A core part of beta decay, an important type of radioactive reaction, involves the conversion of a neutron into a proton within an unstable nucleus. This conversion plays a significant role because it alters the identity of the element:

• In this process, a neutron, which is electrically neutral, transforms into a positively charged proton.
• This conversion increases the atomic number of the element by one, turning it into a different element.
• The overall mass number, however, remains unchanged during this transformation.

The neutron to proton conversion is vital as it enables the nucleus to release the instability, allowing the atom to shift towards a more balanced and stable state. This subtle alteration of particles is what governs the nuclear transformation process at a fundamental level.

Beta Particle Emission

In the context of beta decay, beta particle emission is the process by which a beta particle and an antineutrino are ejected from an atomic nucleus. This happens during the neutron to proton conversion mentioned earlier. Let's break it down:

• A beta particle is essentially a high-speed electron that has negligible mass but carries a negative charge.
• Along with the beta particle, an antineutrino is also emitted, which helps conserve energy and momentum.
• Beta particle emission helps the nucleus reduce energy and reach a more stable state.

The emission is a crucial step because it not only changes the elemental aspects of an atom but also has applications extending beyond theory to practical uses, such as medical imaging and studying radioactive substances. Understanding beta emissions is integral in grasping how unstable nuclei transition into stability.