Question

Explain how beta emission, positron emission, and electron capture affect the neutron-proton ratio.

Short answer

Beta emission decreases the neutron-proton ratio, while positron emission and electron capture increase it.

Step-by-step solution

Understand Beta Emission

In beta emission, a neutron transforms into a proton and an electron. The electron (beta particle) is emitted from the nucleus. This increases the proton number by 1 and decreases the neutron number by 1, thus decreasing the neutron-proton ratio (N/Z).

Understand Positron Emission

In positron emission, a proton is transformed into a neutron and a positron, which is emitted from the nucleus. This decreases the proton number by 1 and increases the neutron number by 1, thus increasing the neutron-proton ratio (N/Z).

Understand Electron Capture

In electron capture, an inner orbital electron is captured by the nucleus and combines with a proton to form a neutron. This decreases the proton number by 1 and increases the neutron number by 1, leading to an increase in the neutron-proton ratio (N/Z).

Compare the Effects

Comparing the three processes: Beta emission reduces the neutron-proton ratio, while both positron emission and electron capture increase the neutron-proton ratio.

Key concepts

Beta Emission

In the process of beta emission, a neutron inside the nucleus transforms into a proton and an electron. The electron, also known as a beta particle, is ejected from the nucleus. This change increases the number of protons by one and decreases the number of neutrons by one, leading to a reduction in the neutron-proton ratio (N/Z).

This process usually occurs in neutron-rich nuclei, where the number of neutrons is significantly greater than the number of protons. By emitting a beta particle, the nucleus moves toward a more stable state with a balanced neutron-proton ratio.

Positron Emission

Positron emission is another type of nuclear decay process in which a proton in the nucleus is converted into a neutron and a positron. The positron is the antimatter counterpart of the electron and is emitted from the nucleus.

This process decreases the proton number by one and increases the neutron number by one, resulting in an increased neutron-proton ratio (N/Z). Positron emission typically occurs in proton-rich nuclei, helping the nucleus achieve greater stability by balancing its neutron and proton numbers.

Electron Capture

Electron capture happens when an inner orbital electron is drawn into the nucleus, where it combines with a proton to form a neutron. The proton count decreases by one while the neutron count increases by one.

This increases the neutron-proton ratio (N/Z). Electron capture usually occurs in proton-rich nuclei, facilitating the transformation of protons into neutrons and steering the nucleus towards a more balanced and stable configuration.

Neutron-Proton Ratio

The neutron-proton ratio (N/Z) is a crucial factor in determining the stability of an atomic nucleus. A balanced ratio helps keep the nucleus stable, while an imbalance can lead to various types of radioactive decay as the nucleus strives for stability.

Beta emission decreases the neutron-proton ratio by converting neutrons to protons. On the other hand, both positron emission and electron capture increase this ratio by converting protons into neutrons.

• High neutron-proton ratio: Expect beta emission.
• Low neutron-proton ratio: Expect positron emission or electron capture.

Understanding these processes helps in grasping how nuclei achieve stability through different nuclear decay processes.