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Science - Chemistry
Standard 1 Objective 3
1 class periods of 60 minutes each
Students will watch a demonstration of the reaction of alkali metals in water.
Lithium, Sodium and Potassium make an excellent demonstration of the periodic trend for ionization energy going down a group. One of the chemical properties that the alkali metals share is that they react violently with water:
2 Na (s) + 2 H2O (l) → 2 NaOH (aq) + H2 (g)
The fact that they produce hydroxides when reacted with water is what gives them their name (alkali).
In order for the reaction to happen, the alkali metals must become ions, losing an electron (ionization energy). Since Potassiums ionization energy is the lowest, the reaction will be most vigorous for Potassium. Likewise, since Lithiums ionization energy is the highest, the reaction will be least vigorous for Lithium. (I like to pull this out of the kids using questions.)
Solutions should be neutralized with vinegar or another weak acid, and then can be washed down the sink.
Lesson Design by Jordan School District Teachers and Staff.