Nuclear Structure
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Questions and Answers

What is a nuclear fusion reaction?

  • A reaction where two light nuclei combine to form a heavier nucleus (correct)
  • A reaction where a neutron is captured by a heavy nucleus
  • A reaction involving the capture of an electron by a nucleus
  • A reaction where a heavy nucleus splits into lighter nuclei

    • In a nuclear fission reaction, what happens?

  • A heavy nucleus absorbs a proton and becomes a lighter nucleus
  • A heavy nucleus splits into two lighter nuclei (correct)
  • A light nucleus captures a neutron and emits a photon
  • Two light nuclei combine to form a single heavy nucleus

    • Which of the following is an application of radioactivity in medicine?

  • Producing heat in nuclear reactors
  • Generating electricity in power plants
  • Detecting and treating tumors (correct)
  • Studying chemical reaction mechanisms

    • How is the number of mass conserved in nuclear reactions?

    <p>The sum of the masses of the reactants equals the sum of the masses of the products</p> Signup and view all the answers

    What does the equation $^{235}U + ^1n \rightarrow ^{139}Xe + ^{95}Sr + 3 ^1n$ represent?

    <p>Fission reaction</p> Signup and view all the answers

    Which of the following statements is true about the nuclear fusion reaction $^2H + ^3H \rightarrow ^4He + ^1n$?

    <p>Two light nuclei combine to form a heavier nucleus and a neutron</p> Signup and view all the answers

    What is the unit of measurement for the activity of a sample?

    <p>Becquerel</p> Signup and view all the answers

    Which device is used to measure the activity of a sample?

    <p>Geiger-Muller counter</p> Signup and view all the answers

    What is the radioactivity level of uranium ore?

    <p>25,000,000 Bq/kg</p> Signup and view all the answers

    How long is the half-life (t1/2) of Cesium-137?

    <p>30 years</p> Signup and view all the answers

    What property does the half-life of a radioactive isotope affect?

    <p>Its decay rate over time</p> Signup and view all the answers

    Which application of radioactivity is used to diagnose cancers?

    <p>Scintigraphy</p> Signup and view all the answers

    What technique is used to determine the age of an ancient object by measuring its activity?

    <p>Carbon dating</p> Signup and view all the answers

    Which radioactive element is used as a fuel in nuclear power plants?

    <p>Uranium</p> Signup and view all the answers

    Who discovered radioactivity in 1896?

    <p>Henri Becquerel</p> Signup and view all the answers

    What type of reactions result from nucleus instability?

    <p>Spontaneous nuclear reactions</p> Signup and view all the answers

    What is emitted during the disintegration of a parent nucleus?

    <p>A nucleus or a ray</p> Signup and view all the answers

    How is the activity of a radioactive sample measured?

    <p>Using a Geiger counter</p> Signup and view all the answers

    What is an example of nuclear fission?

    <p>Fission of Uranium 235</p> Signup and view all the answers

    What is the product of the fusion of $^2_1H$ and $^3_1H$?

    <p>$^4_2He$ and $^1_0n$</p> Signup and view all the answers

    Which application is NOT among those listed for radioactivity?

    <p>Generating wind energy</p> Signup and view all the answers

    Which particles cause ionizations when passing through living matter?

    <p>All of the above</p> Signup and view all the answers

    What is the unit of measurement for the activity of a sample?

    <p>Becquerel (Bq)</p> Signup and view all the answers

    Which process describes the exponential decrease of activity over time?

    <p>Radioactive decay</p> Signup and view all the answers

    What is the half-life of a radioactive isotope?

    <p>Time taken for the activity to decrease to half its initial value</p> Signup and view all the answers

    Which of the following is a medical application of radioactivity?

    <p>Treating tumors with radiotherapy</p> Signup and view all the answers

    Which element is mentioned as a fuel in nuclear power plants?

    <p>Uranium</p> Signup and view all the answers

    What term is used for applying radioactivity to determine the age of ancient objects?

    <p>Carbon dating</p> Signup and view all the answers

    What type of particle is emitted during alpha decay?

    <p>Helium nucleus</p> Signup and view all the answers

    What material can stop beta particles?

    <p>Aluminum sheet</p> Signup and view all the answers

    What happens during a beta-minus ($\beta^-$) decay?

    <p>A neutron transforms into a proton</p> Signup and view all the answers

    Which type of radiation is the most penetrating?

    <p>Gamma rays</p> Signup and view all the answers

    What does the gamma radiation emitted by atoms consist of?

    <p>Electromagnetic waves</p> Signup and view all the answers

    What are the laws of conservation during a nuclear reaction?

    <p>Conservation of mass number and charge</p> Signup and view all the answers

    Where are stable nuclides located on the Segre diagram?

    <p>At the center of the stability band</p> Signup and view all the answers

    What is the symbol for the alpha particle?

    <p>$^4_2He$</p> Signup and view all the answers

    What is the result when a neutron strikes a ${}^{235}U$ nucleus?

    <p>${}^{235}U$ becomes unstable and splits into lighter nuclei, releasing energy and more neutrons.</p> Signup and view all the answers

    Which smaller nuclei can be produced from the fission of ${}^{235}U$?

    <p>${}^{141}Ba$ and ${}^{92}Kr$</p> Signup and view all the answers

    What is a chain reaction in the context of nuclear fission?

    <p>A continuous series of fission reactions caused by released neutrons striking other uranium nuclei.</p> Signup and view all the answers

    What is one application of fission reactions?

    <p>Generating electricity in nuclear power plants.</p> Signup and view all the answers

    Which element is commonly used as a fuel in fission reactions?

    <p>Uranium</p> Signup and view all the answers

    What does the symbol A represent in a nucleus?

    <p>Number of nucleons (mass number)</p> Signup and view all the answers

    What is the charge of a single proton?

    <p>1.602 * 10^-19 C</p> Signup and view all the answers

    How can isotopes be characterized?

    <p>Same number of protons but different number of nucleons</p> Signup and view all the answers

    What ensures the cohesion of the nucleus against electrical repulsive forces?

    <p>Strong interactions</p> Signup and view all the answers

    What usually accompanies the decay of a radioactive nucleus?

    <p>Formation of a new nucleus, emission of a particle, and often emission of a gamma ray</p> Signup and view all the answers

    Which type of radioactive particle consists of two protons and two neutrons?

    <p>Alpha particle</p> Signup and view all the answers

    Which type of radioactivity is the most penetrating?

    <p>Gamma rays</p> Signup and view all the answers

    Which statement about radioactive decay is true?

    <p>It is random and spontaneous</p> Signup and view all the answers

    What results from the transformation of a neutron into a proton?

    <p>Emission of a beta particle</p> Signup and view all the answers

    What differentiates natural radioactivity from artificial radioactivity?

    <p>Natural radioactive nuclei are found in nature</p> Signup and view all the answers

    Study Notes

    Structure of an Atomic Nucleus

    • A nucleus is represented by the symbol X, where X is the chemical symbol of the element.
    • A nucleus consists of protons, neutrons, and electrons.
    • The number of protons (Z) is equal to the atomic number, which determines the element of an atom.
    • The number of neutrons (N) is equal to the mass number (A) minus the atomic number (Z).

    Isotopes

    • Two nuclei are isotopes if they have the same number of protons (Z) but a different number of neutrons (N).
    • Isotopes have the same atomic number but different mass numbers.

    Stability and Instability of Nuclei

    • Forces within a nucleus:
      • Electromagnetic repulsive forces between protons.
      • Strong nuclear forces between nucleons (protons and neutrons).
    • Some nuclei are stable, while others are unstable and can undergo radioactive decay.
    • The stability of a nucleus depends on the number and type of nucleons it contains.

    Radioactivity

    • Radioactivity is a process in which unstable nuclei emit radiation to become stable.
    • Radioactive decay involves the emission of alpha, beta, or gamma radiation.
    • Alpha particles are composed of two protons and two neutrons.
    • Beta particles are high-energy electrons emitted from the nucleus.
    • Gamma radiation is high-energy electromagnetic radiation.
    • Radioactivity is a natural process, but it can also be induced artificially.

    Different Types of Radioactivity

    • Alpha decay: emission of an alpha particle from the nucleus.
    • Beta decay: emission of a beta particle from the nucleus.
    • Gamma decay: emission of gamma radiation from the nucleus.

    Laws of Conservation

    • During a nuclear reaction, the number of protons and neutrons is conserved.
    • The total number of protons and neutrons before the reaction is equal to the total number of protons and neutrons after the reaction.

    Nuclear Reactions

    • Spontaneous nuclear reactions: radioactive decay.
    • Induced nuclear reactions: fission and fusion reactions.
    • Fission: a heavy nucleus splits into two or more lighter nuclei.
    • Fusion: two or more light nuclei combine to form a heavier nucleus.

    Applications of Radioactivity

    • Medical applications: diagnostic techniques (scintigraphy and tomography), cancer treatment (radiotherapy).
    • Scientific applications: exploration of the Earth and its history.
    • Energy production: nuclear power plants.

    Dangers of Radioactivity

    • Ionizing radiation can cause harm to living organisms.
    • Radioactive materials can contaminate the environment and pose health risks.
    • Exposure to radiation can increase the risk of cancer and other health problems.

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    Description

    Learn about the characteristics of a nucleus, including the number of protons, neutrons, and nucléons. Understand the symbols and formulas used to represent a nucleus.

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