Radioactivity and Nuclear Reactions
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Questions and Answers

What is radioactive decay?

  • The combination of lighter atomic nuclei to form a heavier nucleus.
  • A chemical reaction involving the outer electrons of atoms.
  • The sudden temperature change in a substance.
  • The process where a nucleus spontaneously disintegrates and emits radiation. (correct)

Which particle is found in both alpha rays and helium-4 nuclei?

  • Protons (correct)
  • Neutrons
  • Electrons
  • Positrons

What charge do beta rays carry?

  • Positive charge
  • No charge
  • Negative charge (correct)
  • Double positive charge

Who discovered the phenomenon of radioactivity?

<p>Antoine Henri Becquerel (A)</p> Signup and view all the answers

How do gamma rays interact with electric and magnetic fields?

<p>They are unaffected by either field. (A)</p> Signup and view all the answers

Which type of radiation can be separated by electric and magnetic fields?

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

What type of decay does uranium-238 undergo?

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

Which of the following is true regarding nuclear reactions?

<p>They involve changes in the atomic nucleus. (B)</p> Signup and view all the answers

What is the final stable product of the uranium-238 decay series?

<p>Lead-206 (A)</p> Signup and view all the answers

Which isotope starts the second radioactive decay series?

<p>Uranium-239 (B)</p> Signup and view all the answers

Which process is responsible for the transformation of one element into another?

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

What type of reaction occurs during nuclear bombardment?

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

How many naturally occurring radioactive decay series are mentioned?

<p>Three (D)</p> Signup and view all the answers

Which of the following statements is true regarding the decay processes of thorium-232?

<p>It leads to lead-208. (D)</p> Signup and view all the answers

What happens when nuclear particles collide with a nucleus in nuclear bombardment?

<p>The nucleus combines with another to form a more massive nucleus. (B)</p> Signup and view all the answers

What is emitted during the alpha decay of uranium-238?

<p>Alpha particles (D)</p> Signup and view all the answers

What is emitted along with an alpha particle during the decay of Plutonium-239?

<p>Uranium-235 (D)</p> Signup and view all the answers

What is a primary factor that influences nuclear stability?

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

Which of the following magic numbers is associated with protons?

<p>50 (C)</p> Signup and view all the answers

How does nuclear force differ from electric force at nuclear distances?

<p>Nuclear force is a strong attractive force (B)</p> Signup and view all the answers

What does the deviation from the band of stability indicate?

<p>An imbalanced neutron to proton ratio (A)</p> Signup and view all the answers

How many stable isotopes with even numbers of both protons and neutrons exist according to the data?

<p>157 (C)</p> Signup and view all the answers

Which magic number is unique to neutrons and not protons?

<p>126 (C)</p> Signup and view all the answers

What phenomenon does the shell model of the nucleus explain?

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

What is the band of stability?

<p>A cluster of stable nuclides plotted on a graph of protons versus neutrons. (B)</p> Signup and view all the answers

How do nuclides to the left of the band of stability typically decay?

<p>By beta emission. (D)</p> Signup and view all the answers

What happens to the neutron-to-proton ratio as the atomic number (Z) increases?

<p>It increases to about 1.5. (D)</p> Signup and view all the answers

Which nuclides are believed to decay primarily by alpha emission?

<p>Nuclides with Z greater than 83. (D)</p> Signup and view all the answers

What is the effect of beta emission on the neutron-to-proton ratio?

<p>It decreases the neutron-to-proton ratio. (D)</p> Signup and view all the answers

What is emitted during the radioactive decay of uranium-238?

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

What types of decay do nuclides to the right of the band of stability typically undergo?

<p>Positron emission or electron capture. (A)</p> Signup and view all the answers

Why are no stable nuclides known with atomic numbers greater than 83?

<p>Stable configurations are not achievable due to high proton repulsions. (A)</p> Signup and view all the answers

What happens when a positron encounters an electron?

<p>They annihilate each other. (C)</p> Signup and view all the answers

How is the total charge during a nuclear reaction characterized?

<p>It remains constant. (D)</p> Signup and view all the answers

Which of the following elements is an exception with no stable nuclides at atomic numbers 43 and 61?

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

What is the mass number of a helium-4 nucleus?

<p>4 (D)</p> Signup and view all the answers

In a nuclear equation, what does the subscript represent?

<p>Charge of the particle (C)</p> Signup and view all the answers

Which of the following particles carries no charge?

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

If all reactants in a nuclear equation are known except one, what can easily be determined?

<p>Identity of the unknown nucleus (C)</p> Signup and view all the answers

What type of emission is associated with the decay of technetium-99?

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

What did the experiments involving light nuclei primarily demonstrate?

<p>The possibility of transmuting one element to another. (D)</p> Signup and view all the answers

What particles are produced when beryllium is bombarded with alpha particles?

<p>Neutrons (D)</p> Signup and view all the answers

Which of the following is true regarding trans-uranium elements?

<p>They have atomic numbers greater than 92. (C)</p> Signup and view all the answers

What is denoted by the symbol for the projectile particle in nuclear bombardment reactions?

<p>The incoming particle that initiates the reaction. (B)</p> Signup and view all the answers

Which was the first transuranium element produced in a laboratory?

<p>Neptunium-239 (C)</p> Signup and view all the answers

In nuclear reaction notation, which of the following comes first?

<p>The nuclide symbol for the original nucleus. (A)</p> Signup and view all the answers

How was the element neptunium first created?

<p>By bombarding uranium-238 with neutrons. (D)</p> Signup and view all the answers

What is the atomic number of the first transuranium element, neptunium?

<p>93 (B)</p> Signup and view all the answers

Flashcards

Radioactive decay

A process where an atomic nucleus spontaneously disintegrates, releasing radiation.

Nuclear reaction

A reaction that involves changes within the nucleus of an atom, different from a chemical reaction.

Alpha ray

A type of nuclear radiation, consisting of helium-4 nuclei (2 protons, 2 neutrons).

Beta ray

A type of nuclear radiation consisting of high-speed electrons.

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Gamma ray

A type of high-energy electromagnetic radiation from radioactive decay, similar to X-rays.

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Radioactivity

The phenomenon of certain substances spontaneously emitting radiation from their nuclei.

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Antoine Henri Becquerel

The scientist who discovered radioactivity in 1896.

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Nuclear bombardment reaction

A type of nuclear reaction where a nucleus is bombarded by another particle.

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Nuclear Equation

A symbolic representation of a nuclear reaction, showing reactants and products.

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Nuclide Symbol

Represents a nucleus, showing its atomic number (subscript) and mass number (superscript).

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Alpha Particle

A helium nucleus (2 protons and 2 neutrons), represented by ^4He.

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Beta Emission

A nuclear decay where a neutron transforms into a proton and emits an electron (β-particle).

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Positron

A particle with the same mass as an electron, but with a positive charge.

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Gamma Photon

A high-energy particle of electromagnetic radiation.

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Conservation of Charge

In nuclear reactions, the total charge (sum of subscripts) remains constant.

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Conservation of Nucleons

In nuclear reactions, the total number of nucleons (sum of superscripts) remains constant.

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Nuclear Force

Strong force of attraction between nucleons (protons and neutrons) acting at very short distances.

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Magic Numbers

Specific numbers of protons or neutrons that give extra stability to a nucleus.

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Magic Number for protons

Numbers of protons for especially stable nuclei, i.e., 2, 8, 20, 28, 50, 82, 114.

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Magic Number for neutrons

Numbers of neutrons for especially stable nuclei, i.e., 2, 8, 20, 28, 50, 82, 126.

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Band of Stability

A region in a graph of number of protons vs. number of neutrons where stable nuclei are found.

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N/P ratio

Neutron-to-proton ratio; a factor affecting nuclear stability.

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Shell model of the nucleus

Model describing protons and neutrons arranged in energy levels.

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Nuclear Stability

The tendency of a nucleus to remain unchanged, or resist decay.

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Neutron-to-proton Ratio

The ratio of neutrons to protons in a nucleus, which affects its stability.

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Nuclide to the left of the Band of Stability

Nuclides with a higher neutron-to-proton ratio than stable, they tend to decay by beta emission.

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Nuclide to the right of the Band of Stability

Nuclides with a lower neutron-to-proton ratio than stable, they decay by positron emission or electron capture.

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Positron Emission/Electron Capture

Radioactive decay where a proton in the nucleus transforms into a neutron, either emitting a positron (anti-electron) or capturing an electron.

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Alpha Emission

A type of radioactive decay where an unstable nucleus emits an alpha particle (helium nucleus).

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Technetium and Promethium

The only two elements with Z less than 83 that do not have any stable isotopes.

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Transmutation

The process of changing one element into another element by altering the nucleus of an atom.

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Neutron

A subatomic particle with no charge and a mass slightly greater than that of a proton. Found in the nucleus of an atom.

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Abbreviated Notation

A concise way to represent a nuclear bombardment reaction using symbols for the target, projectile, ejected particle, and product nucleus.

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Transuranium Elements

Elements with atomic numbers greater than uranium (Z=92), which is the naturally occurring element with the highest atomic number.

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Neptunium

The first transuranium element discovered, with atomic number 93. Produced by bombarding uranium-238 with neutrons.

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Plutonium

A transuranium element with atomic number 94, produced by bombarding uranium with deuterons.

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Deuteron

The nucleus of a deuterium atom, consisting of one proton and one neutron.

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Radioactive Series

A sequence where one radioactive nucleus decays into another, creating a chain of decay processes until a stable nucleus is formed.

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Uranium-238 Decay Series

A naturally occurring radioactive series starting with uranium-238 and ending with lead-206, involving alpha and beta decay steps.

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Ernest Rutherford

The scientist who discovered that transmutation could be achieved by bombarding nitrogen nuclei with alpha particles.

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Why are radioactive decay series important?

They explain how elements change over time and how stable isotopes are formed, providing insight into the natural processes of radioactive elements.

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What is the final product of all three naturally occurring radioactive series?

An isotope of lead (Pb), a stable element that is the end point of these decay chains.

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What is the difference between radioactive decay and nuclear bombardment?

Radioactive decay is spontaneous, where a nucleus decays on its own, while nuclear bombardment involves a collision with another particle or nucleus to initiate a reaction.

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Study Notes

Radioactivity

  • Radioactivity is the spontaneous disintegration of a nucleus, releasing radiation.
  • Radiation can be electrons, nuclear particles (neutrons, helium-4 nuclei), or electromagnetic radiation.
  • Radioactive decay was discovered by Antoine Henri Becquerel in 1896, observing uranium minerals affecting photographic plates.
  • Radiation from uranium minerals can be separated into alpha (α), beta (β), and gamma (γ) rays using electric and magnetic fields.
  • Alpha rays have a positive charge, consisting of helium-4 nuclei.
  • Beta rays have a negative charge, consisting of high-speed electrons.
  • Gamma rays are unaffected by electric and magnetic fields, being electromagnetic radiation similar to X-rays, with shorter wavelengths.

Nuclear Reactions

  • In nuclear reactions, changes occur in the nucleus, independent of the chemical environment.
  • Two types of nuclear reactions are radioactive decay and nuclear bombardment reactions.
  • Radioactive decay involves the spontaneous disintegration of a nucleus.
  • Nuclear reactions can be represented using nuclear equations, similar to chemical reactions.
  • Uranium-238, after alpha decay, turns into thorium-234.
  • The equation for the α-decay of uranium-238 is given as: 238U → 234Th + 4He 92 90 2

Nuclear Equations

  • Reactant and product nuclei use their nuclide symbols.

  • Particles are represented using subscripts for charge and superscripts for mass number.

    • Proton (p): ¹₁H or ¹₁P
    • Neutron (n): ¹₀n
    • Electron (e-): 0-₁e
    • Positron (e+): 0+₁e

  • In nuclear equations, the sum of the subscripts for the reactants equals the sum of the subscripts for the products.

  • The sum of the superscripts for the reactants equals the sum of the superscripts for the products.

  • Example of beta decay, using technetium-99:

    99Tc → 99Ru + e 43 44 -1

Nuclear Stability

  • Nuclear stability depends upon:
    • Presence of magic numbers (2, 8, 20, 28, 50, 82, and 126) of protons or neutrons.
    • Deviation from band of stability (neutron-to-proton ratio).
    • Pairs of protons and pairs of neutrons.
  • Stable nuclides cluster in a band of stability on a graph of neutrons versus protons.
  • Nuclides away from the band of stability are generally unstable and decay.
  • Nuclides with atomic numbers > 83 are often unstable and decay by alpha emission.

Radioactive Decay Series

  • Radioactive decay series describes a sequence of radioactive decays of a nucleus, producing a stable isotope.
  • An example involves uranium-238, decaying through multiple steps into lead-206.

Nuclear Bombardment

  • Changing one element to another by bombarding the nucleus with particles or nuclei.
  • Example: Rutherford's experiment bombarding nitrogen with alpha particles, producing oxygen and a proton.
  • Different notation for nuclear reactions, such as Be(α,n)¹²C, where Be is the target, α is the particle, n is the neutron, and ¹²C is the new nuclide.

Applications of Nuclear Radiations

  • Preparing transuranium elements.
  • Dating old rocks and objects using radioactive isotopes (e.g., carbon-14).
  • Medical applications using radioisotopes as tracers (e.g., technetium-99m, thallium-201).

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Description

Explore the fascinating world of radioactivity and nuclear reactions in this quiz. Understand the process of radioactive decay, the types of radiation, and the principles guiding nuclear reactions. Test your knowledge about discoveries and the nature of nuclear properties.

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