Bonding Practice Questions (Page 3 of 3) in pdf

22. What is meant when it is said that water is "polar"?

This means water has a positive end (pole) and a negative end (pole). This is the result of an

uneven sharing of electrons between the oxygen and the hydrogen along with a asymmetrical

shape.

23. Why does a styrofoam cup dissolve in acetone (finger nail polish remover) but not in water?

Styrofoam is a nonpolar hydrocarbon and water is very polar. The rule for solubility is “like

dissolves like” so water will NOT dissolve the Styrofoam.

24. Why can a paper clip float on the surface of water even though it is denser than water?

Because of surface tension. Water molecules on the surface are pulled inwards and downwards

with an unbalanced force, therefore, it is harder to break surface molecules apart and the paper

clip floats.

25. What shape does water form when placed on top of a penny? Why?

A sphere because of surface tension. The water molecules on the surface attract each other more

strongly than other molecules so they want to form the shape with the least amount of surface

area which is a sphere.

26. How does detergent work to help clean your clothes?

Detergents are surfactants which means they lower the surface tension of water by getting in

between the water molecules and weakening their attraction for each other. As a result, the dirt is

able to be pulled from the pores in your clothes and get washed down the drain.

27. Describe how soap works to clean oil off your skin and hair.

Soap is the sodium or potassium salt of a fatty acid. A fatty acid is a long hydrocarbon chain

which has a carboxylic acid (R-COOH) group at the end of the chain. When treated with Lye

(NaOH) it produces a salt (R-COO

). This salt has a long nonpolar hydrocarbon chain which

dissolves in the oil and a polar end which dissolves in the water. It acts like an emulsifying agent

and links the two immiscible liquids (oil/dirt and water) together.

28. What is the difference between "dry cleaning" and regular laundry?

Regular laundry uses polar water as the solvent to wash the clothes. A “Dry Cleaner” uses a

nonpolar solvent such as tetrachloroethene, C

, to wash the

clothes.

29. Identify each of the following as Ionic, Metallic, Covalent Network, or Covalent Molecular:

a. MgSO

b. H

O c. C

d. Au e. CaCO

f. C

g. SO

h. Hg

i. NaI

diamond

Ionic

30. For each of the following, draw the Lewis Dot structure, give the ABx formula, state the shape

of the molecule, state whether the molecule is symmetrical or asymmetrical, state whether the

molecule is polar and nonpolar, and state the main type of intermolecular attractive force holding

the molecules together. A) CH

B) SO

C) HCN

D) HClO

E) PCl

F) NH

Bonding Practice Questions Page 3

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