P4 Atomic Structure and Radioactivity Flashcards
Q: Why are some atomic nuclei unstable?
A: Some atomic nuclei are unstable due to an imbalance in the forces within the nucleus.
Q: What forces exist within the nucleus?
A: Forces exist between the protons and neutrons in the nucleus, including the strong nuclear force that holds them together.
Q: How is Carbon-14 different from stable Carbon-12?
A: Carbon-14 has two extra neutrons compared to stable Carbon-12.
Q: Why are some isotopes unstable?
A: Some isotopes are unstable due to their large size or because they have too many or too few neutrons.
Q: What happens when radiation moves away from the nucleus?
A: As radiation moves away from the nucleus, it carries away energy, which reduces the overall energy of the nucleus and makes it more stable.
Q: What is the process of emitting radiation called?
A: The process of emitting radiation is called radioactive decay.
Q: Is radioactive decay a predictable process?
A: No, radioactive decay is a random process, meaning it is impossible to know exactly when a particular nucleus will decay.
Q: What are objects containing radioactive nuclei called?
A: Objects containing radioactive nuclei are called sources of radiation.
Q: How do sources of radiation decay?
A: Sources of radiation decay at different rates, which are defined by their activity.
Q: What is activity in terms of radiation?
A: Activity is the rate at which the unstable nuclei in a source of radiation decay.
Q: What is activity measured in?
A: Activity is measured in Becquerels (Bq).
Q: What is 1 Becquerel (Bq)?
A: 1 Becquerel is equal to 1 nucleus in the source decaying in 1 second.
Q: What are the different types of radiation that can be emitted from an unstable nucleus?
A: The types of radiation that can be emitted from an unstable nucleus are Alpha, Beta, and Gamma radiation.
Q: What are Alpha particles?
A: Alpha particles are helium nuclei consisting of 2 protons and 2 neutrons. They have a charge of +2 and can be affected by an electric field.
Q: What are Beta particles?
A: Beta particles are fast-moving electrons with a charge of -1. They are produced when a neutron in the nucleus decays into a proton and an electron.
Q: What are Gamma rays?
A: Gamma rays are electromagnetic waves with no charge and no mass. They have the highest energy of all types of electromagnetic radiation.
Q: How is alpha radiation stopped?
A: Alpha radiation is stopped by paper or a few centimetres of air.
Q: How is beta radiation stopped?
A: Beta radiation can be stopped by a few millimetres of aluminium.
Q: How is gamma radiation stopped?
A: Gamma radiation is only partially stopped by thick lead or concrete.
Q: What is ionising power?
A: Ionising power refers to the ability of radiation to ionise atoms, meaning it can remove electrons and create charged particles.
Q: Which type of radiation has the most ionising power?
A: Alpha radiation is the most ionising because it has a +2 charge and interacts strongly with atoms.
Q: Which type of radiation has the least ionising power?
A: Gamma radiation has the least ionising power because it has no charge and interacts weakly with atoms.
Q: What is the range of alpha radiation in air?
A: Alpha radiation has a range of only a few centimetres in air.
Q: What is the range of beta radiation in air?
A: Beta radiation has a range of a few tens of centimetres in air.
Q: What is the range of gamma radiation in air?
A: Gamma radiation has an infinite range in air, though its intensity decreases with distance.
Q: What is half-life?
A: Half-life is the time it takes for half of the nuclei in a sample of a radioactive isotope to decay.
Q: What is contamination?
A: Contamination is the unwanted presence of radioactive materials on other materials or surfaces.
Q: What is irradiation?
A: Irradiation is the process of exposing a material to alpha, beta, or gamma radiation. It does not make the material radioactive but can kill or damage living cells.
Q: What is the difference between contamination and irradiation?
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A: Contamination occurs when radioactive materials get onto a surface or object, making it radioactive. Irradiation is the exposure to radiation, but the material does not become radioactive.
Q: How can we protect against radiation exposure?
A: To protect against radiation exposure, we use shielding (such as lead-lined suits), airtight suits to prevent contamination, and limit exposure time.
Q: What happens during alpha decay?
A: During alpha decay, an alpha particle (helium nucleus) is emitted, causing the mass number to decrease by 4 and the atomic number to decrease by 2.
Q: What is an example of alpha decay?
A: Polonium-212 undergoes alpha decay to form Lead-208 and an alpha particle.
Q: What happens during beta decay?
A: In beta decay, a neutron changes into a proton and an electron. The electron (beta particle) is emitted, and the atomic number of the nucleus increases by 1.
Q: What is an example of beta decay?
A: Carbon-14 undergoes beta decay to form Nitrogen-14 and a beta particle.
Q: What happens during gamma decay?
A: During gamma decay, a gamma ray is emitted from an unstable nucleus. This reduces the nucleus’s energy but does not change its mass or atomic number.
Q: Why is radioactive decay random?
A: Radioactive decay is random because it is impossible to predict when a specific nucleus will decay, although the probability of decay over a given time period can be estimated.
Q: How does half-life relate to radioactive decay?
A: Half-life is the time it takes for half of the radioactive nuclei in a sample to decay, and it helps estimate the rate at which radioactive decay occurs.
