Relative Formula Mass

Cards (29)

  • What should you be able to state by the end of the video?
    What is meant by relative formula mass
  • What is the relative atomic mass of an element?
    Average mass of isotopes weighted by abundance
  • What does the term abundance refer to in isotopes?

    How common an isotope is
  • What is the atomic number of chlorine?
    17
  • How many neutrons does the chlorine isotope with mass number 35 have?
    18 neutrons
  • How many neutrons does the chlorine isotope with mass number 37 have?
    20 neutrons
  • What is the average mass number of chlorine as seen on the periodic table?
    35.5
  • Why is the mass number of chlorine 35.5?
    It is weighted for the abundance of isotopes
  • What is the definition of relative formula mass?
    Sum of relative atomic masses in a formula
  • What symbol represents relative formula mass?
    It has a specific symbol
  • Does relative formula mass have units?
    No, it has no units
  • Does relative formula mass involve large numbers?
    No, it never involves big numbers
  • What is the relative formula mass of methane?
    16
  • How many carbon and hydrogen atoms are in methane?
    1 carbon and 4 hydrogen atoms
  • What is the relative atomic mass of carbon?
    12
  • What is the relative atomic mass of hydrogen?
    1
  • How do you calculate the relative formula mass of methane?
    Add 1 times 12 and 4 times 1
  • What happens when you put a large two in front of the formula for methane?
    It indicates two molecules of methane
  • What is the relative formula mass of calcium sulfate?
    136
  • What is the relative atomic mass of calcium?
    40
  • What is the relative atomic mass of sulfur?
    32
  • What is the relative atomic mass of oxygen?
    16
  • How do you calculate the relative formula mass of calcium sulfate?
    Add 1 times 40, 1 times 32, and 4 times 16
  • What is the relative formula mass of magnesium hydroxide?
    58
  • What is the relative atomic mass of magnesium?
    24
  • How do you calculate the relative formula mass of magnesium hydroxide?
    Add 1 times 24, 2 times 16, and 2 times 1
  • What should you remember about relative formula mass?
    It has no units
  • What are the key facts about relative formula mass?
    • No units
    • Never involves big numbers
  • What are the steps to calculate the relative formula mass of a compound?
    1. Identify the number of each atom
    2. Multiply by their relative atomic masses
    3. Sum all the values