New Reactivity

• What do half-equations show in a reaction?

  Oxidation or reduction part of a reaction
• Why are half-equations useful?

  They help break down redox reactions
• What are the steps to write half-equations?

  1. Identify the species involved
  2. Determine oxidation and reduction
  3. Balance the atoms
  4. Balance the charges by adding electrons
• What does oxidation mean in terms of electrons?

  Loss of electrons
• What does reduction mean in terms of electrons?

  Gain of electrons
• What does OIL stand for in redox reactions?

  Oxidation Is Loss
• What does RIG stand for in redox reactions?

  Reduction Is Gain
• How do you ensure atoms are balanced in half-equations?

  Make sure the number of atoms is the same
• How do you balance charges in half-equations?

  Add the correct number of electrons
• How many electrons are released per magnesium atom in the reaction with oxygen?

  2 electrons per Mg atom
• What is the total number of electrons needed for the reduction of O₂ in the magnesium and oxygen reaction?

  4 electrons
• What are the key rules for writing half-equations?

  1. Write the changing element or ion
  2. Balance the atoms
  3. Balance the charges by adding electrons
  4. Ensure electrons lost = electrons gained
• Where are electrons placed in oxidation half-equations?

  On the right side
• Where are electrons placed in reduction half-equations?

  On the left side
• What are the main concepts to remember about redox reactions?

  • Oxidation = loss of electrons
  • Reduction = gain of electrons
  • Reactivity series of metals
  • Displacement reactions
  • Rusting and prevention methods
• What is the reactivity series?

  Order of metals based on reactivity
• What are displacement reactions?

  A more reactive metal replaces a less reactive one
• What are some methods to prevent rusting?

  Barrier methods, galvanizing, sacrificial protection
• What is rusting?

  Iron reacting with oxygen and water
• What is the final summary of what you need to know about half-equations?

  They show electron transfer in oxidation and reduction