relative atomic mass

• What is the definition of isotopes?

  Atoms of the same element with different numbers of neutrons
• What is the atomic number of chlorine isotopes?

  17
• How many neutrons does the isotope of chlorine with mass number 35 have?

  18 neutrons
• How many neutrons does the isotope of chlorine with mass number 37 have?

  20 neutrons
• What is the mass number for chlorine as shown on the periodic table?

  35.5
• How is the relative atomic mass calculated from isotopes?

  It is a weighted average of the mass numbers based on their abundance
• What does the term "abundance" refer to in the context of isotopes?


  How common each isotope is
• Why is the relative atomic mass of chlorine closer to 35 than to 37?

  Because the isotope with mass number 35 is three times more abundant
• What is the formula to calculate relative atomic mass based on isotopes?

  • Relative atomic mass =

  \frac{(mass\ number\ of\ isotope\ 1 \times percent\ abundance\ of\ isotope\ 1) + (mass\ number\ of\ isotope\ 2 \times percent\ abundance\ of\ isotope\ 2)}{100}
• What is the relative atomic mass of boron if isotope one has a mass number of 10 and an abundance of 20%, and isotope two has a mass number of 11 and an abundance of 80%?

  10.8
• How is the relative atomic mass of boron rounded in the periodic table?

  It is rounded up to 11
• What are the mass numbers and abundances of the isotopes of magnesium?


  Isotope 1: 24 (79%), Isotope 2: 25 (10%), Isotope 3: 26 (11%)
• What is the relative atomic mass of magnesium based on its isotopes with mass numbers 24, 25, and 26 and their respective abundances?


  24.3
• How is the relative atomic mass of magnesium rounded in the periodic table?

  It is rounded down to 24