Element

• Mole

  A very large number that represents the number of particles (atoms, molecules, or ions) in one mole of any substance
• The mole is a really useful concept in chemistry
• Relative atomic mass

  The mass of a single atom of an element, calculated from the average masses of the isotopes weighted for their abundance
• Relative atomic mass has no units
• Calculating the number of moles

  Mass of element in grams / Relative atomic mass = Number of moles
• Calculating number of moles

  • 48 g of magnesium (relative atomic mass 24) = 2 moles
  • 120 g of calcium (relative atomic mass 40) = 3 moles
  • 252.2 g of iron (relative atomic mass 56) = 4.5 moles
  • 4,064 g of sulfur (relative atomic mass 32) = 127 moles
• Mole calculations are not too tricky