Question

Which of the following molecules or ions is polar? (20 POINTS)

Answer 1

For NO3- molecule(fig.1)

1.  Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in NO3 are polar.

2. In the geometry of the molecule  bond polarities cancel out each other (since it is a vector) so NO3- ion molecule is non polar

3.   Nitrate (NO3-)ion  geometry would be trigonal planar

For CCl4 molecule(fig.2)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in CCl4 are polar.

2. It is a completely symmetrical molecule.

3.Carbon is the centre of CCl4 have four covalent bonds and it has no lone pairs. They are all equidistant the C-Cl bond polarities cancel out. So CCl4 molecule is non polar

For NH3 molecule(fig.3)

1. Bonds are created between elements with different electronegativity, most bonds would be polar. Bonds in NH3 molecule are polar.

2.  it has a pyramidal structure.

3. the individual N-H bond dipoles don't cancel out. This dipole moment for the molecule indicates that NH3 is a polar molecule

For SF6 molecule(fig.4)

1.F is more electronegative than S. So the bonds are polar.

2. The symmetry of the molecule is  symmetrical so that the dipole moments of bonds cancel correspond so the molecule is non-polar.

3. it has octahedral structure