Use the chart to determine which is an example of a highly polar covalent bond. ca – cl fe – o h – s f – f done elements electronegativity aluminum (al) 1.61 calcium (ca) 1 carbon (c) 2.55 chlorine (cl) 3.16 fluorine (f) 4 hydrogen (h) 2.2 iron (fe) 1.83 nitrogen (n) 3.04 oxygen (o) 3.44 phosphorus (p) 2.19 potassium (k) 0.82 silicon (si) 1.9 sulfur (s) 2.58