Atomic Structure and Subatomic Particles Quiz
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Questions and Answers

What is the rate at which unstable atomic nuclei decay called?

  • Radiation
  • Activity (correct)
  • Half-life
  • Count-rate
  • Which type of nuclear decay is considered highly penetrating?

  • Alpha decay
  • Gamma decay (correct)
  • Beta decay
  • Neutron decay
  • What particle is emitted during beta decay?

  • Electron (correct)
  • Neutron
  • Alpha particle
  • Helium nucleus
  • What happens to the mass of the nucleus during alpha decay?

    <p>Decreases (B)</p> Signup and view all the answers

    The count-rate from a radioactive source is measured in which unit?

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

    What is the change in charge of the nucleus during beta decay?

    <p>Increases by 1 (A)</p> Signup and view all the answers

    Which statement about gamma decay is correct?

    <p>It does not affect mass or charge. (C)</p> Signup and view all the answers

    Which type of radiation is weakly penetrating and highly ionising?

    <p>Alpha radiation (B)</p> Signup and view all the answers

    What is the main purpose of technetium in medical applications?

    <p>To act as a tracer due to its gamma emission properties (C)</p> Signup and view all the answers

    What is a potential drawback of using gamma emitters in chemotherapy?

    <p>They may also damage surrounding healthy tissue (B)</p> Signup and view all the answers

    Which statement about nuclear fission is true?

    <p>It releases energy when a large nucleus splits and emits neutrons (C)</p> Signup and view all the answers

    How does technetium minimize harm from radiation during medical procedures?

    <p>It is present only for a short time before it decays (A)</p> Signup and view all the answers

    What typically triggers nuclear fission in unstable nuclei?

    <p>Absorption of a neutron (C)</p> Signup and view all the answers

    What is the relative charge of a proton?

    <p>+1 (B)</p> Signup and view all the answers

    What determines the mass number of an atom?

    <p>Sum of protons and neutrons (A)</p> Signup and view all the answers

    Which statement about isotopes is correct?

    <p>Isotopes have different numbers of neutrons (C)</p> Signup and view all the answers

    When does an atom absorb electromagnetic radiation?

    <p>When an electron moves to a higher orbit (D)</p> Signup and view all the answers

    What is the typical radius of an atom?

    <p>$1 imes 10^{-10}$ meters (C)</p> Signup and view all the answers

    What is true about a neutral atom?

    <p>It has no charge (C)</p> Signup and view all the answers

    What was the primary contribution of Dalton to atomic theory?

    <p>Proposing that atoms are indivisible spheres (B)</p> Signup and view all the answers

    What happens when an electron gains sufficient energy?

    <p>It leaves the atom and forms a positive ion (D)</p> Signup and view all the answers

    What did the Gold Foil Experiment demonstrate about the structure of the atom?

    <p>Most of the atom is composed of empty space (B)</p> Signup and view all the answers

    Which particle has a negligible mass compared to protons and neutrons?

    <p>Electron (A)</p> Signup and view all the answers

    According to Rutherford's model of the atom, where are the electrons located?

    <p>In a cloud around the nucleus (D)</p> Signup and view all the answers

    What did Bohr's model address that Rutherford's model did not?

    <p>The stability of electron orbits (C)</p> Signup and view all the answers

    Which of the following describes the Plum Pudding Model?

    <p>Electrons are evenly distributed in a positive medium (B)</p> Signup and view all the answers

    What key aspect did Rutherford's findings reveal about the nucleus?

    <p>It is positively charged and contains most of the atom's mass (C)</p> Signup and view all the answers

    What was one of the main criticisms of the Rutherford model?

    <p>It proposed that electrons would spiral into the nucleus (A)</p> Signup and view all the answers

    In which year did JJ Thomson discover the electron?

    <p>1897 (B)</p> Signup and view all the answers

    What initiates the fission process by providing the necessary energy for the nucleus to split?

    <p>A neutron (B)</p> Signup and view all the answers

    What occurs after the uranium nucleus splits during fission?

    <p>It breaks down into two smaller nuclei and releases kinetic energy. (A)</p> Signup and view all the answers

    What is a potential consequence of an uncontrolled nuclear fission chain reaction?

    <p>It increases at an exponential rate. (D)</p> Signup and view all the answers

    In the process of nuclear fusion, what happens to the mass of the two small nuclei compared to the mass of the resulting heavier nucleus?

    <p>It decreases, with the lost mass converted into energy. (B)</p> Signup and view all the answers

    Why is fusion considered more efficient than fission for energy production?

    <p>It releases a greater amount of energy per reaction. (D)</p> Signup and view all the answers

    What describes the effect of radioactive contamination on materials?

    <p>It involves the transfer of radioactive atoms to an object. (D)</p> Signup and view all the answers

    How is the ratio of net decline of radioactive nuclei calculated after X half-lives?

    <p>N is halved repeatedly for each half-life. (A)</p> Signup and view all the answers

    What is the main difference between contamination and irradiation?

    <p>Irradiation lasts only for a short period of time. (A)</p> Signup and view all the answers

    Why is peer review essential for scientific reports on radiation effects in humans?

    <p>It ensures the accuracy of initial measurements. (A)</p> Signup and view all the answers

    Which of the following is classified as a source of background radiation?

    <p>Cosmic rays. (D)</p> Signup and view all the answers

    What happens to an object that is irradiated?

    <p>It is exposed to nuclear radiation without becoming radioactive. (A)</p> Signup and view all the answers

    Which unit is used for measuring radiation dose?

    <p>Sieverts (Sv). (C)</p> Signup and view all the answers

    What effect does occupation or location have on background radiation levels?

    <p>It can affect the levels of background radiation. (A)</p> Signup and view all the answers

    Flashcards

    Dalton's atomic model

    Atoms are tiny, indivisible spheres.

    Thomson's Plum Pudding Model

    The atom is a positive sphere with negative electrons embedded.

    Rutherford's Gold Foil Experiment

    Experiment that showed the atom's nucleus is small and positively charged.

    Rutherford's model of the nucleus

    Atom has a central positive nucleus with orbiting electrons.

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    Bohr's atomic model

    Electrons orbit the nucleus in specific energy levels.

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    Atomic model evolution

    Scientific understanding of atom's structure changed over time.

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    Empty space in atom

    Most of an atom's volume is empty space.

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    Atomic Nucleus

    The tiny, dense, central core of an atom.

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    Atomic Structure

    An atom has a positively charged nucleus (containing protons and neutrons) surrounded by negatively charged electrons.

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    Subatomic particles

    Particles smaller than an atom, including protons, neutrons, and electrons.

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    Isotopes

    Atoms of the same element with the same number of protons but different numbers of neutrons.

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    Mass number

    The total number of protons and neutrons in an atom.

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    Proton number

    The number of protons in an atom.

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    Electron arrangement

    Electrons orbit the nucleus at different energy levels.

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    EM radiation absorption

    When electrons move further from the nucleus, the atom absorbs EM radiation.

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    EM radiation emission

    When electrons move closer to the nucleus, the atom emits EM radiation.

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    Technetium use in medicine

    Technetium-99m is used as a medical tracer because it quickly decays into a safe isotope, allowing for body scan detection.

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    Nuclear Fission

    The splitting of a large, unstable nucleus, releasing energy and more neutrons.

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    Fission Trigger

    A neutron absorption is often necessary for fission to occur in an unstable nucleus.

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    Gamma emitters in chemotherapy

    Gamma rays from these emitters target cancerous cells, while also affecting healthy tissue.

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    Uranium/Plutonium Fission

    Uranium or plutonium are frequently used in fission reactions because they are large and unstable.

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    Chain Reaction (Fission)

    A self-sustaining process where one nuclear fission event triggers further fission events.

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    Mass-Energy Conversion (Fusion)

    In fusion, some of the mass of the combining nuclei is converted into energy.

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    Uncontrolled Chain Reaction

    A chain reaction where the rate of fission events rapidly increases, as seen in nuclear weapons.

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    Atomic Orbitals

    Fixed regions in an atom where electrons reside.

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    Proton

    A positively charged subatomic particle.

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    Neutron

    A neutral subatomic particle found in the nucleus.

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    Radioactive Decay

    The process where unstable nuclei release radiation to become more stable.

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    Activity (radioactive)

    The rate at which a radioactive source decays.

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    Count Rate

    Number of decays recorded per second by a detector.

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    Alpha Decay

    Radioactive decay emitting an alpha particle (helium nucleus).

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    Beta Decay

    Radioactive decay emitting a beta particle (electron).

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    Net Decline of Radioactive Nuclei

    The reduction in the number of radioactive nuclei after a certain number of half-lives. It's calculated by repeatedly halving the initial number.

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    Radioactive Contamination

    Unwanted radioactive atoms on a material. The hazard comes from the decaying atoms releasing radiation.

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    Irradiation

    Exposing an object to radiation, but not making it radioactive.

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    Peer Review (Scientific Reports)

    Essential when studying radiation effects on humans to ensure accuracy and prevent dangerous safety levels.

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    Background Radiation

    Weak radiation constantly emitted from natural sources like cosmic rays, rocks and nuclear fallout.

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    Radiation Dose Measurement (Sv)

    A unit to measure radiation exposure. Levels may change depending on an individual's location and/or occupation.

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    Half-Life

    The time it takes for half of a radioactive substance to decay.

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    Study Notes

    Atomic Structure

    • Atoms are composed of a positively charged nucleus surrounded by negatively charged electrons.
    • The nucleus contains protons (positive charge) and neutrons (neutral charge).
    • Electrons have negligible mass compared to protons and neutrons.
    • The typical radius of an atom is 1 × 10⁻¹⁰ meters.
    • The radius of the nucleus is significantly smaller, approximately 10,000 times smaller than the atom's radius.

    Subatomic Particles

    • Proton: Relative mass of 1, relative charge of +1.
    • Neutron: Relative mass of 1, relative charge of 0.
    • Electron: Relative mass of 0 (or 0.0005), relative charge of -1.

    Isotopes

    • Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons.
    • They have the same atomic number (number of protons) but different mass numbers (sum of protons and neutrons).
    • Examples include Carbon-12, Carbon-13, and Carbon-14.

    Electron Arrangement

    • Electrons exist in different energy levels, or shells, around the nucleus.
    • Electron arrangements in atoms may change with the interaction of electromagnetic radiation.
    • The number of electrons is equal to the number of protons in a neutral atom.

    Atoms and Electromagnetic Radiation

    • When electrons transition from higher to lower energy levels, they emit electromagnetic radiation.
    • When electrons transition from lower to higher energy levels, they absorb electromagnetic radiation.
    • Electrons can completely leave the atom if they absorb sufficient energy, leading to the formation of a positively charged ion.

    Atomic Models

    • Dalton's Model: Atoms are indivisible spheres.
    • Thomson's Model (Plum Pudding): Atoms have a positive sphere with negatively charged electrons embedded.
    • Rutherford's Model: Most of the atom is empty space, with a dense, positive nucleus at the center and electrons orbiting it.
    • Bohr's Model: Electrons exist in specific energy levels (orbits) around the nucleus.

    Radioactive Decay

    • Radioactive decay is the spontaneous process where unstable atomic nuclei emit radiation as they transform into more stable forms.
    • Activity is the rate at which radioactive nuclei decay.
    • Count rate is the rate at which particles are detected.
    • Decay can be measured in Becquerels (Bq).

    Types of Radioactive Decay

    • Alpha decay: Emission of an alpha particle (helium nucleus).

    • Beta decay: Emission of a beta particle (electron or positron).

    • Gamma decay: Emission of a gamma ray.

    • Each type of decay affects the mass and/or charge of the nucleus differently.

    Half-Life

    • Half-life is the time required for half of the radioactive nuclei in a sample to decay.
    • Half-lives are constant and used to predict the rate of decay in large samples of radioactive material.
    • Half-lives can range from fractions of a second to billions of years depending on the isotope.

    Contamination vs. Irradiation

    • Contamination involves the presence of radioactive material on an object, meaning the material is radioactive.
    • Irradiation involves the exposure of an object to radiation but does not make it radioactive.

    Background Radiation

    • Background radiation is weak radiation from natural sources such as cosmic rays and rocks.
    • Measurement of radiation dose is in Sieverts (Sv).

    Nuclear Fission

    • In nuclear fission, a large, unstable nucleus is split into smaller nuclei, releasing energy.
    • A neutron triggers the initial splitting process and produces more neutrons, leading to a chain reaction (e.g. nuclear bomb).
    • Fission is useful for generating energy in power plants.

    Nuclear Fusion

    • In nuclear fusion, small nuclei combine to form a larger, more stable nucleus, releasing enormous amounts of energy.
    • The source of energy from the sun is fusion.
    • Fusion is a potentially more efficient energy source than fission, but practical methods for controlling fusion reactions are not yet developed.

    Uses of Radioactive Substances

    • Tracers (like Technetium-99m): Used in medicine to follow the passage of substances through the body.
    • Chemotherapy: Uses gamma rays to damage cancer cells.

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    Test your understanding of atomic structure, subatomic particles, and isotopes with this quiz. Explore the key concepts surrounding protons, neutrons, electrons, and the arrangement of these particles within an atom. Perfect for students studying physics and chemistry!

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