Problem 32 - A Complete Resource Book in Chemistry for JEE Main

Question

In a radioactive decay, an emitted electron comes from (a) the nucleus of atom (b) the orbit with principal quantum number 1 (c) the inner orbital of the atom (d) the outermost orbit of the atom

Step-by-Step Solution

Answer

The emitted electron comes from the nucleus of the atom (option a).

Step 1: Understanding Radioactive Decay

Radioactive decay is a process by which the nucleus of an unstable atom loses energy by emitting radiation. In terms of electrons, this can involve the emission of a beta particle, which is a high-speed electron or positron.

Step 2: Identify the Source of Emitted Electrons in Beta Decay

In beta decay, the emitted electron comes from the nucleus, not from electron orbits surrounding the nucleus. This occurs when a neutron in the nucleus transforms into a proton, emitting an electron in the process.

Step 3: Evaluate the Options

Given the context of beta decay, the electron is emitted directly from the nucleus due to the transformation of a neutron. Thus, only option (a) 'the nucleus of atom' is correct, as the emitted electron in radioactive decay originates from within the nucleus, not from atomic orbits.

Key Concepts

Beta Decay

Beta decay is a fascinating process that occurs in the world of nuclear physics. It takes place when an unstable nucleus transforms to achieve a more stable state. During beta decay, a neutron in the nucleus is transformed into a proton. This transformation results in the emission of a beta particle. A beta particle is actually a high-speed electron or positron. Think of it as nature's way of re-arranging the particle furniture within the nucleus to reach a more comfy configuration. This whole process redefines the nuclear identity of an atom because the change from a neutron to a proton effectively changes the element itself. For instance, carbon can transform into nitrogen through beta decay.

• Beta decay can result in two types of emissions: beta-minus ( ) where an electron is emitted, and beta-plus ( ⁺) where a positron is emitted.
• This transformation helps the atom achieve stability by correcting neutron-to-proton ratio imbalances.

Understanding beta decay is crucial for fields like nuclear energy and medical radiation, as both utilize these processes in different ways.

Nuclear Processes

Nuclear processes fundamentally occur at the heart of an atom – the nucleus. These processes involve complex interactions and transformations of nuclear particles: protons and neutrons, collectively known as nucleons. The nucleus binds these particles together with a strong nuclear force. However, in an unstable nucleus, these forces are not perfectly balanced, leading to natural transformations like beta decay. Nuclear processes are essential for several natural and technological applications:

• Fission: Splitting of a heavy nucleus into smaller ones, releasing a large sum of energy. Utilized in nuclear reactors.
• Fusion: Light nuclei combine to form a heavier nucleus, releasing energy. Powers the sun and stars.
• Radioactive Decay: Unstable nuclei lose energy by emitting radiation, such as during beta decay.

These processes are the driving force behind natural phenomena like stellar evolution and also the technology of nuclear power. Each nuclear process plays a significant role in energy transformation and elemental formation in the universe.

Emission of Radiation

The emission of radiation is a process where unstable atomic nuclei lose excess energy through the release of particles or electromagnetic waves. This process makes them stable. Radiation can penetrate different materials to various extents, depending on its type and energy level. There are several types of radiation emitted during nuclear transformations:

• Alpha Radiation: Consists of helium nuclei (2 protons and 2 neutrons). It's the least penetrating due to its size.
• Beta Radiation: Involves the ejection of electrons or positrons, as seen in beta decay. It's more penetrating than alpha radiation.
• Gamma Radiation: High-energy photons, extremely penetrating, generally requiring dense materials like lead for shielding.

The control and understanding of radiation emissions have applications in medicine, power generation, and safety protocols. Being able to manage and utilize radiation safely is pivotal to harnessing its benefits while minimizing risks.