Question

8. H = 2.1 Li = 1.0 Be = 1.5 B = 2.0 C = 2.5 N = 3.0 O= 3.5 F = 4.0 Na = 1.0 Mg = 1.2 Al = 1.5 Si = 1.8 P = 2.1 S = 2.5 Cl = 3.0 K = 0.8 Ca = 1.0 Ga = 1.6 Ge = 1.8 As = 2.0 Se = 2.4 Br = 2.8 Use the electronegativities above and your knowledge of the shape of HCCH to determine the molecular polarity of HCCH explaining your answer in detail.

Answer 1

Bond polarities arise from bonds between atoms of different electronegativity. When we have more complex molecules, we must consider the possibility of molecular polarities that arise from the sums of all of the individual bond polarities. To do full justice to this discussion we really need to consider the concept of vectors (mathematical quantities that have both direction and magnitude). For simple molecules we can usually get a first approximation using simple figures.

We have the molecular of HCCH with a triple blond between the two C, what gives us a linear shape.

We will find arrows to point the polarity from the H to the C because the C is more electronegativity.

The two vectors should be identical and pointed in exactly opposite directions. The sum of these two vectors must be zero because the vectors must cancel one another out.

So we will have a nonpolar molecule.