Question

Discuss how radioactive atoms gain stability

Short answer

Radioactive atoms gain stability through the processes of alpha, beta, and gamma decay. Alpha decay involves the emission of an alpha particle, reducing the atomic number by 2 and mass number by 4. Beta decay has two types: beta minus, in which a neutron is converted into a proton and an electron is emitted, and beta plus, in which a proton is converted into a neutron and a positron is emitted. Gamma decay occurs when an excited nucleus emits excess energy in the form of gamma rays, resulting in a nucleus with a lower energy state. These decay processes enable the atom to adjust its proton-to-neutron ratio or decrease its energy state, thereby leading to a more stable nucleus.

Step-by-step solution

Understand Radioactive Decay and Stability

Radioactive decay is the process through which the unstable nuclei of radioactive atoms achieve greater stability. This occurs through the emission of various particles and energy. The primary aim of radioactive decay is to achieve a more stable nucleus, which often has a specific ratio of protons to neutrons. In general, there are three types of decay processes that we'll discuss: alpha decay, beta decay, and gamma decay, each of which aids the nucleus in gaining stability.

Alpha Decay

In alpha decay, the unstable nucleus emits an alpha particle, which consists of 2 protons and 2 neutrons. This loss of 2 protons and 2 neutrons reduces the atomic number by 2 and mass number by 4, resulting in a more stable nucleus. For example, if an atom with atomic number Z and mass number A undergoes alpha decay, the resulting nucleus will have atomic number Z-2 and mass number A-4. The general equation for alpha decay is: \[ \hspace{15mm} _Z^A X \rightarrow _{Z-2}^{A-4} Y + _2^4 \alpha \]

Beta Decay

In beta decay, there are two types: beta minus (β-) and beta plus (β+) decay. Both types lead to a more stable proton-to-neutron ratio within the nucleus. In beta minus decay, a neutron is converted into a proton and an electron (called a beta particle) is emitted. In beta plus decay, a proton is converted into a neutron and a positron (the antiparticle of the electron) is emitted. The general equations for beta minus and beta plus decay are: Beta minus decay: \[ \hspace{15mm} _Z^A X \rightarrow _{Z+1}^A Y + e^- + \bar{\nu}_e \] Beta plus decay: \[ \hspace{15mm} _Z^A X \rightarrow _{Z-1}^A Y + e^+ + \nu_e \]

Gamma Decay

Gamma decay occurs when an excited nucleus emits excess energy in the form of gamma rays. This type of decay does not change the atomic number or mass number of the atom but results in a nucleus with a lower energy state, which is more stable. Gamma decay often occurs after alpha or beta decay, as the nucleus is often left in an excited state following these processes. The general equation for gamma decay is: \[ \hspace{15mm} ^* _Z^A X \rightarrow _Z^A X + \gamma \] In conclusion, radioactive atoms gain stability through the processes of alpha, beta, and gamma decay. Each of these decay processes allows the atom to adjust its proton-to-neutron ratio or decrease its energy state, thereby leading to a more stable nucleus.

Key concepts

Alpha Decay

Alpha decay is a fascinating process that occurs at the heart of unstable atoms as they strive for stability. Imagine a helium nucleus, a tiny particle made up of two protons and two neutrons, being ejected from an atom's nucleus. This event signifies alpha decay, which results in the reduction of the atomic number by two and the mass number by four.

Let's take an example to illustrate this: suppose we have an atom of uranium-238. This heavy atom wants to shed some weight to become more stable, so it undergoes alpha decay and ejects an alpha particle to transform into thorium-234.

The alpha particles are relatively heavy and carry a double positive charge due to the two protons. Once emitted, alpha particles can be easily stopped by something as thin as a sheet of paper or even the outer layer of human skin. However, if inhaled or ingested, they can be a health hazard due to their high ionizing power.

Beta Decay

Beta decay represents a different pathway to stability taken by unstable nuclei. It can go one of two ways: either a neutron is too shy and decides to dress up as a proton, ejecting an electron in the process—this is beta minus decay; or a proton feels like it's one too many and morphs into a neutron, releasing a positron—this is beta plus decay.

In beta minus decay, an atom gains a proton while in beta plus decay, it loses one. Both these processes aim to balance the ledger of protons and neutrons to reach a stable configuration. Unlike alpha particles, beta particles—electrons or positrons—have much smaller mass and can penetrate deeper into materials, making them both interesting and potentially dangerous.

To visualize these processes, consider carbon-14, which undergoes beta minus decay to become stable nitrogen-14. On the flip side, nitrogen-13 may undergo beta plus decay to achieve stability in the form of carbon-13.

Gamma Decay

Gamma decay is the nucleus' way of letting off steam. When a nucleus feels excited—packed with too much energy—it can relax by emitting a gamma ray, a form of pure energy without mass or charge.

Gamma rays are like the X-rays at a doctor's office, or the UV light that gives you a sun tan; they're all part of the electromagnetic spectrum, but gamma rays are even more powerful. These energetic photons can zoom through most materials, requiring heavy lead or concrete to block them effectively. Despite being daunting because of their penetrative power, gamma rays are used beneficially in medicine for imaging and cancer treatment.

Consider a nucleus that has just done the hard work of alpha or beta decay. Often, it's like after a good workout—still buzzing with energy. It then uses gamma decay to cool down to its new, more relaxed and stable state without changing its identity in terms of protons or neutrons.