chemistry 2

• Starter


  1. Draw an atom of oxygen

  2. Draw an oxide ion (oxygen once it has reacted), label how it has changed

  3. Draw an atom of lithium

  4. Determine how many atoms of lithium would be needed to react with one oxygen atom, and why
• Ionic equation


  Shows how the ions are changing in a reaction
• Writing ionic equations


  1. Split the reaction into two half equations

  2. Look at the two changes
• Half equation


  Shows what is happening to one species in a reaction
• Half equations


  • Fluorine gains one electron
  • Sulfur gains two electrons
  • Magnesium loses 2 electrons
• Completing half equations

  Add electrons to complete the half equations
• Completing half equations


  • Describe in a sentence what each half equation shows
• Combining half equations to form ionic equations

  Electrons must cancel out
• Writing ionic equations


  1. Write a half equation for an aluminium atom losing three electrons to become an aluminium ion

  2. Write a half equation for a fluorine molecule (F2) gaining electrons to become fluoride ions (F-)

  3. Combine and balance them to make an ionic equation
• Writing ionic equations


  1. Write a half equation for a fluorine molecule (F2) gaining electrons to become fluoride ions (F-)

  2. Write a half equation for chloride ions (Cl-) losing their extra electrons to make a chlorine molecule (Cl2)

  3. Combine and balance them to make an ionic equation