Stable and Unstable Nuclei | Radioactivity | Physics | FuseSchool

Summary

This video explains how to determine if an atom is stable or unstable, focusing on the concept of radioactive decay. It covers the structure of atoms, the strong nuclear force that holds protons and neutrons together, and the conditions that make a nucleus unstable. The video describes three types of decay: alpha, beta minus, and beta plus, detailing how each occurs and how it changes the atom. It also explains the neutron-proton (NZ) graph to predict decay, and concludes by emphasizing that unstable nuclei give off particles to regain stability.

Takeaways

• 🔬 Atoms consist of protons, neutrons, and electrons; protons and neutrons form the nucleus, while electrons orbit around it.
• 🧲 A strong nuclear force holds protons and neutrons together, determining the stability of a nucleus.
• 🌌 Most stable nuclei, formed during the Big Bang, have remained stable for billions of years.
• ⚛️ Unstable nuclei have an imbalance in the number of protons or neutrons, leading to radioactive decay.
• 🧪 Radioactive decay occurs as atoms try to stabilize by emitting particles like protons or neutrons.
• 🧷 Alpha decay occurs when an atom loses an alpha particle (two protons and two neutrons), reducing its mass and atomic number.
• 💡 Beta minus decay happens when a neutron changes into a proton, releasing a high-energy electron called a beta particle.
• 🔄 Beta plus decay occurs when a proton is converted into a neutron and a positron, reducing the atomic number by one.
• 📉 The stability of an isotope can be predicted by its position on a proton-neutron graph, with unstable isotopes decaying to stabilize.
• 🚨 Isotopes with more than 82 protons are prone to alpha decay due to their instability.

Q & A

What is an atom composed of?

An atom is composed of subatomic particles called protons, neutrons, and electrons. The protons and neutrons form the central nucleus, while electrons orbit the nucleus.

What role does the strong nuclear force play in atomic stability?

The strong nuclear force holds the positive protons and neutral neutrons together in the nucleus, determining whether the nucleus is stable. It provides the energy needed to keep the nucleus intact.

Why are some nuclei unstable?

Some nuclei are unstable because they have an imbalance in the number of protons and neutrons. Either too many protons or too many neutrons can upset the strong nuclear forces, making the nucleus unstable.

What is radioactive decay, and why does it occur?

Radioactive decay is the process by which unstable nuclei try to balance themselves by giving off excess protons or neutrons. It occurs because the strong nuclear force is unable to hold the nucleus together in its current form.

What are the three types of radioactive decay discussed in the video?

The three types of radioactive decay discussed are alpha decay, beta minus decay, and beta plus decay.

What happens during alpha decay?

During alpha decay, an atom loses an alpha particle, which consists of two protons and two neutrons. As a result, the atom's mass number decreases by four, and its atomic number decreases by two, forming a new element two places lower on the periodic table.

How does beta minus decay change an atom's structure?

In beta minus decay, a neutron is transformed into a proton and an electron. The proton remains in the atom, while the electron is emitted as a beta particle. The atomic number increases by one, but the mass number stays the same, forming a new element one place higher on the periodic table.

What occurs during beta plus decay, and how does it affect the atom?

In beta plus decay, a proton is converted into a neutron and a positron (a positively charged beta particle). The mass number remains the same, but the atomic number decreases by one, forming a new element one place lower on the periodic table.

How can we determine if a radioisotope is stable or unstable?

We can determine a radioisotope's stability by examining its position on a proton-neutron (NZ) graph. If the radioisotope lies left or right of the stability line, it is unstable and likely to decay to achieve stability.

Which type of decay is likely for isotopes with a high number of protons (usually more than 82)?

Isotopes with a high number of protons (usually more than 82) are likely to undergo alpha decay to achieve stability.