Question

PART A: Choose the bond below that is least polar

A. C-F

B. C-Cl

C. C-Br

D. C-I

E. C-O

Please explain how the answer is found

PART B: Which of the following molecules is polar?

A. CO₂

B. CCl₄

C. H₂

D. NO₂

E. O₃

Please explain your answer

PART C: Which of the following polyatomic ions is polar?

A. NH₄⁺

B. OH^-

C. SO₄^-

D. PO₄^3-

Please explain your answer

Answer 1

1.The least polar bond will have the lowest electronegativity differece. They will be the two elements which have electronegativities that are closest.

That would be carbon and iodine.

you need to draw the Lewis electron dot structure and assign a shape to them. The shapes that are symmetrical are polar. The symmetrical shapes are not polar unless one of the binding sites is a different atom than then others. (For example, SF6 is octahedral and non-polar because it is symmetrical while SF5Cl is not symmetrical and is polar.)

NO2 is angular with an uneven number of electrons and is polar. The geometry of the molecule is bent because of a non-bonding pair of electrons. The bent geometry causes the polarity.
CCl4 is tetrahedral and is not polar.

O3 (ozone) has no polar bonds, yet the molecule has a net dipole moment.

H2 is nonpolar because the bonding pair of electrons is shared equally between the two hydrogen atoms.

CO2 is linear which means both C-O dipoles cancel and the overall molecule is nonpolar

3.   C. SO₄^-

The sulfur can only make 6 bonds. The O2 each want to make 4 bonds, but cant, since sulfur cannot form 8 bonds. As a result, 2 oxygen atoms make double bonds and thus are happy, so to speak, while the other 2 oxygen atoms can only make 1 bond each. They are not happy. The SO4 -2 ion is unstable, as are all polyatomic ions. This is why you will never see a polyatomic ion alone unless suspended in an aqueous solution.

NH₄⁺ The ammonia cation is positively charged polymatic ion ' NH4+ ions have N and H atoms that are covalently bonded, but they are not molecules