Question

activity b: molecular polarity
get the gizmo ready: select the molecular polarity tab.
introduction: ionic bonds, like those found in nacl, form crystalline solids. covalent bonds, on the other hand, usually form discrete molecules. a polar molecule, while neutral overall, has a slight positive charge on one end and a slight negative charge on the other.
question: what determines the polarity of molecules?

1. observe: notice that the molecules containing polar covalent bonds are grouped together at lower left, and the molecules containing nonpolar covalent bonds are at lower right. drag the h₂o molecule into the simulation area.

a. are the individual bonds in this molecule polar or nonpolar?
b. click turn on electric field. what do you notice?
c. the electric field consists of a positively charged plate on one side and a negatively charged plate on the opposite side. which side of the h₂o molecule is attracted to the positive plate, and why do you think this attraction occurs?
d. click reverse field. why does the h₂o molecule rotate 180°?
a polar molecule, such as h₂o, changes its orientation when placed in an electric field. the positive end of the molecule is attracted to the negative plate, while the negative end is attracted to the positive plate. drag this molecule into the polar bin.

1. observe: drag the ch₄ molecule into the simulation area.

a. do you think this molecule will rotate in the electric field? why or why not?
b. turn on the electric field. is this molecule polar or nonpolar? drag the ch₄ molecule into the appropriate bin.

Explanation:

Step1: Analyze H₂O bond polarity

Oxygen is more electronegative than hydrogen. In H₂O, the O - H bonds are polar due to the electronegativity difference.

Step2: Observe H₂O in electric field

When the electric field is turned on, the H₂O molecule aligns itself with the field because it is polar.

Step3: Determine H₂O - plate attraction

The oxygen - rich (negative) side of the H₂O molecule is attracted to the positive plate. This is because opposite charges attract and oxygen has a partial negative charge due to its higher electronegativity.

Step4: Explain H₂O rotation on field reversal

When the field is reversed, the H₂O molecule rotates 180° because the positive end now gets attracted to the new negative plate and the negative end to the new positive plate.

Step5: Analyze CH₄ polarity

CH₄ has a symmetric tetrahedral shape. The individual C - H bonds have a small electronegativity difference, but due to the symmetry, the molecule is non - polar overall. So it will not rotate in an electric field.

Step6: Determine CH₄ nature in field

When the electric field is turned on, since CH₄ is non - polar, it shows no alignment or rotation in the field.

Answer:

1.
A. Polar
B. The H₂O molecule aligns with the electric field.
C. The oxygen - rich side (negative side) is attracted to the positive plate because oxygen has a partial negative charge due to higher electronegativity, and opposite charges attract.
D. Because the positive end of the polar H₂O molecule is now attracted to the new negative plate and the negative end to the new positive plate.
2.
A. No, because CH₄ is a non - polar molecule due to its symmetric tetrahedral shape.
B. Non - polar