isotopes + ram

• What are isotopes?

  Different forms of the same element
• How do isotopes differ from each other?

  They have different numbers of neutrons
• What do isotopes have in common?

  Same number of protons
• What is the relationship between atomic number and mass number in isotopes?

  Same atomic number, different mass numbers
• What does the relative atomic mass (A_r) represent?

  Average mass of one atom of the element
• How is the relative atomic mass compared?

  Compared to 1/12 of carbon-12's mass
• What happens to A_r if an element has only one isotope?

  A_r equals its mass number
• How is A_r calculated for elements with multiple isotopes?

  Average of mass numbers, weighted by abundance
• What are the stable isotopes of chlorine mentioned?

  Chlorine-35 and chlorine-37
• Why might A_r not be a whole number?

  Due to the average of isotopes' masses
• What is isotopic abundance?

  Different quantities of isotopes present
• How do you calculate relative atomic mass from isotopic abundances?

  Use the formula involving abundance and mass number
• What is the formula for calculating relative atomic mass (A_r)?

  A_r = sum of (abundance x mass number) / total abundances
• How do you calculate the relative atomic mass of boron with isotopes boron-10 and boron-11?

  • Boron-10 abundance: 4
  • Boron-11 abundance: 16
  • Calculation:
  • A_r = (4 × 10 + 16 × 11) / (4 + 16) = 10.8
• How would you calculate silicon's relative atomic mass with isotopes Si-28, Si-29, and Si-30?

  Use their respective abundances in the formula
• What are the abundances of silicon's isotopes Si-28, Si-29, and Si-30?

  92.2%, 4.7%, and 3.1%
• What is the first step in calculating silicon's relative atomic mass?

  Identify the abundances of each isotope
• How does the presence of multiple isotopes affect the relative atomic mass of an element?

  It results in an average that may not be whole