Lesson 3, Topic 5
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6.4.4 Defining redox in terms of electron transfer (DEMO)

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Click the cards to match the terms about oxidation and reduction in terms of oxygen loss or gain.

Oxidation and reduction always take place together. So, in the reaction between magnesium and oxygen,

  • magnesium gains oxygen; magnesium is oxidized
  • oxygen loses oxygen; oxygen is reduced.

Saying “oxygen loses oxygen” sounds awkward; we need a broader definition of oxidation and reduction.

Magnesium oxide (MgO) is an ionic compound, and remember, ionic compounds are formed due to electron transfer from a metal to a nonmetal.

Analyze a diagram The diagram below shows the formation of magnesium oxide (MgO) through ionic bonding.

  • Observe the electron transfer in the diagram.
  • Identify the element that loses electrons and the element that gains electrons.
  • For each element, compare the number of electrons in the electron shells before and after electron loss or gain.

magnesium transfer two electrons to oxygen to form magnesium oxideResults

Magnesium (Mg) is oxidized by a gain of oxygen or a loss of electrons.

  • Oxidation is the gain of oxygen/ Oxidation is the loss of electrons.

Oxygen (O) is reduced by a gain of electrons from magnesium.

  • Reduction is the loss of oxygen/ Reduction is the gain of electrons.