Lesson 5 - Ions
Student Performance Objectives
1. Define ion, cation and anion.
2. Define ionic bond, and show how an ionic bond forms.
3. Explain the relationship between the words ion, electrolyte, and mineral.
4. Describe a simple experiment to show that ions can carry an electrical current.
5. Explain the importance of unpaired electrons in the chemistry of the human body utilizing
the terms: free radical and antioxidant.
1. Ion - charged particles (e.g., atoms or atomic groupings called radicals) having unequal numbers of protons and electrons.
2. Cation: examples - Na+, K+, Mg+2, Ca+, H+, OH-.
3. Anion: examples - Cl-, HCO3-?, HPO4-2, and H2PO4-1
B. Formation through redox reactions (see below, Lesson 8, part B5)) and resultant attraction of
the oppositely charged ions forming the ionic bond - use Na and Cl as examples.
C. Relationship of ions, electrolytes and minerals - an electrolyte is a solution that carries an
electrical current (such as the body fluids), but in more common usage, electrolytes are the
most commonly found and most important ions in human body tissues - sodium, potassium,
calcium, magnesium, chloride, bicarbonate, and the phosphates. In nutritional jargon, the
commonly found ions/electrolytes are referred to as minerals.
D. DEMONSTRATION: The point is to show the ability of charged particles in a solution, ions,
to carry an electrical current. Using the "light apparatus" demonstrate the inability of
distilled water to carry an electrical current and light up the bulb. Then demonstrate the
inability of a glucose solution, which is unionized in water, to light up the bulb. Then
demonstrate the ability of a small amount of NaCl to light up the bulb and the ability of
increasing amounts of NaCl added to the solution to make the bulb light up even more
E. Importance of unpaired electrons in chemical reactivity,
1. Concept of free radicals and the body's defense against them as the Antioxidant
defense system. See http://www.healthchecksystems.com/antioxid.htm
a. Natural generation of free radicals from the cellular energy generating
organelles - the mitochondria.
b. Potentially damaging effects of free radicals on DNA, lipids, and proteins.
c. Antioxidant defense system
(1) Enzymes - e.g., superoxide dismutase (SOD), catalase
(2) Cofactors - minerals like selenium, zinc, and manganese
(3) Vitamins like ascorbic acid (Vitamin C) and the tocopherols (Vitamin E).
2. Importance of free radicals in the killing mechanisms of the leucocytes.
3. Importance of free radicals in the initial origin of life when there were no enzymes for