Page 1:

• The physical properties of a substance are dictated by whether or not a molecule is polar

• Examples of polar and nonpolar molecules are given in Model 1

• A polar bond is indicated by one circle being blank, while a nonpolar bond has both circles colored

Page 2:

• Formaldehyde (CH2O) is trigonal planar

• The shape of a molecule cannot explain polarity, as molecules of all shapes can be polar or nonpolar

• Nonpolar molecules may contain polar bonds, while polar molecules always contain polar bonds

• The presence or absence of a lone pair of electrons can explain the polarity of molecules

Page 3:

• In a nonpolar molecule, polar bonds are arranged on opposite sides, while in a polar molecule, polar bonds are on the same side

• In a nonpolar molecule, lone pairs of electrons are on opposite sides, while in a polar molecule, lone pairs of electrons are on the same side

• Nonpolar molecules are symmetric about multiple planes of symmetry

Page 4:

• Polar molecules have an unequal distribution of charge, caused by polar bonds or lone pairs of electrons

• The angle between two polar bonds in a molecule needs to be 180 degrees for the molecule to be nonpolar

• The angle between any of the four polar bonds in a molecule needs to be 109.5 degrees for the molecule to be nonpolar

• If a molecule contains only one polar bond and no lone pairs, it cannot be made nonpolar

Page 5:

• The table is filled in to determine if each molecule is polar or nonpolar

• The three-dimensional structures of each molecule are drawn

• Carbon tetrafluoride (CF4) is nonpolar

• Water (H2O) and sulfur dioxide (SO2) are polar

• Phosphorous pentachloride (PCl5) and hydrogen sulfide (H2S) are also polar

Page 5:

• The polarity of a molecule can be quantified as the dipole moment.

  • Dipole moment is measured in debyes.

• The abbreviation for the unit "debye" is D.

• NH3 is the most polar molecule according to the given dipole moments.

• Possible explanations for the changes in dipole moments between the three molecules should be discussed.

• Polar bonds in Model 2 can be determined using a table of electronegativity values.

  • A large difference in electronegativity is characteristic of a polar bond.

• Arrows should be drawn next to significantly polar bonds in Model 2 to show the direction of polarity.

• Lone pairs in a molecule also provide a dipole, and arrows should be drawn pointing away from the center atom for any lone pairs in Model 2.

Page 6:

• NH3 is the most polar molecule because there is a high concentration of negative charge in the center atom.

• NF3 is the least polar molecule because all the arrows point out, balancing each other.

• The phosphorus trifluoride molecule (PF3) has a larger dipole moment (1.03 D) compared to the nitrogen trifluoride molecule in Model 2.

  • The larger dipole moment could be due to a difference in electronegativity.

• The molecules should be ranked in order of polarity from least to most, using arrows on each molecule to support the answer.

• CS2 has a larger dipole moment compared to SO2 because of the presence of polar bonds and asymmetrical structure.

• SF6 has a greater dipole moment compared to CF4 because of the greater concentration of lone electron