1.1.4 Isotopes and Relative Atomic Mass

• What are isotopes defined as?

  Different forms of the same element
• What is the central part of an atom called?

  Nucleus
• What is the x-axis label of the graph?

  Z-N
• What is the name of the positively charged particle in an atom?

  Proton
• What is the y-axis label of the graph?

  Stable
• What does the color scale on the right represent?

  Half-life in years
• What can you infer about the stability of nuclei based on the information in this graph?

  • Nuclei with Z-N values close to the stable region (blue/green) are more stable
  • Nuclei with Z-N values far from the stable region (red/yellow) are less stable and have shorter half-lives
  • The stable region appears to be a diagonal band, suggesting a relationship between Z and N for stable nuclei
• What affects the mass of an isotope?

  Number of neutrons
• Steps to calculate RAM using weighted averages

  1️⃣ Multiply the mass of each isotope by its natural abundance.

  2️⃣ Add up all the values obtained in the previous step.

  3️⃣ Divide the total by 100 to get the RAM.
• What does RAM allow accurate calculation of in chemical reactions?

  Chemical formulas and ratios
• What is the relative atomic mass (RAM) calculated using weighted averages based on?

  Isotope masses and abundances
• What is RAM used for in industrial processes?

  Quality control
• The relative atomic mass of copper is 63.62 amu.


  True
• Isotopes of an element have the same number of neutrons.

  False
• Electrons are located in the shells and have a negative charge.

  True
• Match the subatomic particle with its location and charge:

  Proton ↔️ Nucleus, +1

  Neutron ↔️ Nucleus, 0

  Electron ↔️ Shells, -1
• Match the Carbon isotope with its distinguishing characteristic:

  Carbon-12 ↔️ Mass number of 12

  Carbon-14 ↔️ 2 more neutrons than Carbon-12
• How could this graph be used to design new stable isotopes or predict the stability of radioactive isotopes?

  • Identify regions of the graph with longer half-lives to target for synthesizing new stable isotopes
  • Use the graph to predict the stability of radioactive isotopes and estimate their half-lives
  • Analyze trends in the stable region to understand the underlying nuclear physics principles
  • Combine this graph with other data to develop more comprehensive models of nuclear stability
• What is the contribution of Copper-65 to the RAM of copper?

  20.15 amu
• Protons are located in the nucleus and have a positive charge.


  True
• What is the name of the outermost layer of an atom?

  Electron shell
• Which subatomic particles make up atoms?

  Protons, neutrons, electrons
• What is the name of the neutral particle in an atom?

  Neutron
• How could you use this graph to predict the stability of a nucleus with a given Z and N?

  • Locate the Z and N values of the nucleus on the graph
  • Determine where it falls on the color scale to estimate the half-life
  • Nuclei in the blue/green regions are more stable with longer half-lives
  • Nuclei in the red/yellow regions are less stable with shorter half-lives
• How do the relative masses of the main atomic particles compare?

  • Protons and neutrons have approximately the same mass
  • Electrons have a much smaller mass compared to protons and neutrons
• The relative atomic mass of chlorine is 35.5 amu.

  True
• What is relative atomic mass (RAM)?

  Weighted average of isotope masses
• What are the limitations of using this graph to analyze nuclear stability?

  • The graph only shows a 2D relationship between Z and N, but nuclear stability also depends on other factors like nuclear shell structure
  • The graph has a limited range of Z and N values, so it may not be applicable for all nuclei
  • The color scale is a rough estimate of half-life and does not provide precise quantitative information
  • The graph does not show any information about the specific nuclear processes or decay modes
• What is the range of Z-N values shown in the graph?

  0 to 100
• What is the charge of a neutron?

  0
• What is the mass of Chlorine-37 in atomic mass units (amu)?

  37 amu
• What is the key difference between Carbon-12 and Carbon-14?

  Number of neutrons
• How many protons does Carbon-14 have?

  6
• Carbon-14 is heavier than Carbon-12 because it has more protons.

  False
• What is the RAM of chlorine?

  35.5
• What does the term "atomic number" refer to in the context of isotopes?

  Number of protons
• RAM gives heavier isotopes more importance based on their abundance in nature.


  True
• How do the charges of the main atomic particles relate to each other?

  • Protons have a positive charge
  • Electrons have a negative charge
  • Neutrons have no charge (are neutral)
• What is the name of the central part of an atom?

  Nucleus
• What are the main components of an atom?

  • Electron shell
  • Nucleus
  • Protons
  • Neutrons