Question

Why do nuclei that are neutron-poor emit \(\alpha\) particles or positrons or undergo electron capture?

Short answer

Neutron-poor nuclei emit \\(\\alpha\\) particles, positrons, or undergo electron capture to achieve a stable proton-neutron balance.

Step-by-step solution

Understanding Nuclei Stability

Nuclei are stable when they have a balanced ratio of protons to neutrons. If a nucleus is neutron-poor, it has too many protons in comparison to neutrons, making it unstable.

Types of Decay for Neutron-poor Nuclei

When a nucleus is neutron-poor, it may emit particles or undergo certain processes to achieve a more stable state. The common types of decay in such cases are alpha decay, positron emission, and electron capture.

Alpha Decay Explanation

In alpha decay, the nucleus emits an \(\alpha\) particle, which consists of 2 protons and 2 neutrons. This decreases the number of protons, moving the nucleus toward a more balanced proton-neutron ratio.

Positron Emission Explanation

Positron emission involves a proton in the nucleus converting into a neutron while releasing a positron. This decreases the proton count, thus reducing the neutron deficiency.

Electron Capture Explanation

Electron capture is a process where an inner orbital electron is captured by the nucleus, causing a proton to transform into a neutron. This also reduces the proton count and moves the nucleus towards a more stable state.

Key concepts

Neutron-Poor Nuclei

Understanding neutron-poor nuclei is crucial in nuclear physics. These nuclei have an imbalance in their subatomic particles. They contain too many protons relative to the number of neutrons, which contributes to their instability.
Due to this imbalance, the nucleus seeks a stable configuration. To achieve stability, it undergoes certain decay processes that lower the number of protons or increase the number of neutrons.
By doing so, the nucleus attempts to restore a balance closer to that found in stable nuclei.

Alpha Decay

Alpha decay is a fascinating process that plays a significant role in the stabilization of neutron-poor nuclei. During this type of decay, the nucleus releases an alpha particle.
An alpha particle is composed of 2 protons and 2 neutrons.
This release reduces the total number of protons and helps the nucleus reach a more stable state by improving the proton-to-neutron ratio.
Key points to remember about alpha decay include:

• It decreases both the atomic number and mass number of the original nucleus.
• The stability of the nucleus post-decay is often higher than that of the original nucleus.

Positron Emission

Positron emission is another mechanism employed by neutron-poor nuclei to achieve stability. In this decay process, a proton within the nucleus is transformed into a neutron.
This transformation is accompanied by the emission of a positron, which is essentially a positively charged electron. This event helps decrease the number of protons, aiding the nucleus in balancing its proton-neutron ratio.
Consider these aspects of positron emission:

• It lowers the atomic number by one, keeping the mass number constant.
• This decay mode is common in proton-rich or neutron-poor isotopes.

Electron Capture

Electron capture is a unique process that neutron-poor nuclei may undergo to become more stable. During this process, the nucleus captures one of its inner orbiting electrons.
This electron interacts with a proton, effectively transforming it into a neutron. The capture of the electron reduces the number of protons, which aids in rectifying the proton-neutron imbalance.
Key features of electron capture include:

• Like positron emission, it reduces the atomic number without changing the mass number.
• It is often an option for heavier isotopes or when there is not enough energy for positron emission.