Physical Science
Chapter 6 Review Questions
12-17-07
P 178 Name an advantage to each model: the ball-and-stick model and the spacefilling model.
A ball and stick model shows bond length, and a space-filling model shows relative atom
sizes.
P 180 How is the hardness of minerals explained by minerals’ chemical structure?
The hardness of minerals is explained by the fact that their chemical structure consists of
rigid networks of bonded atoms.
Section 1 Review page 182
1. Classify the following substances as mixtures or compounds
a. air: mixture
b. CO: compound
c. SnF2: compound
d. pure water: compound
2. Draw a ball and stick model of a boron trifluride, BF3, molecule. In this molecule,
a boron atom is attached to three fluorine atoms. Each F-B-F bond angle is 120
degrees, and all B-F bonds are the same length.
3. Explain why silver iodide, AgI, a compound used in photography, has a much
higher melting point than vanillin, C8H8O3, a sweet-smelling compound used in
flavoring.
Silver Iodide has a much higher attraction between particles, a structure of positive
of negative ions. Vanillin consists of molecules.
4. Explain why glass, which is made of mostly SiO2, is often used to make
cookware.
SiO2 has a high melting point. It does not melt when heated to high cooking
temperatures.
5. Predict which molecules have a greater attraction for each other: C3H8O
molecules in liquid rubbing alcohol or CH4 molecules in methane gas.
The C3H80 have a greater attraction than the CH4 because they are closer together and
they are moving more slowly than those in a gas.
6. A pictometer (pm) is equal to 1x 10 -12 m. The O-H bond lengths in water are
95.8 pm, while S-H bond lengths in dihydrogen sulfide are 135 pm. Why are S-H
bonds longer than O-H bonds?
The sulfur atoms are larger than oxygen atoms by one electron energy level.
P 184: What holds two ionic bonded atoms together?
In an ionic bond, ions are held together by the attraction between their opposite charges.
P 186: What holds two covalently bonded atoms together?
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Physical Science
Chapter 6 Review Questions
Covalently bonded atoms are held together by the sharing of the electrons between the
atoms.
P 188: What is one property of metals that you can see in the picture?
Copper can be stretched into thin wires, and is shiny.
P 189: Why are parentheses used in a chemical formula for a compound that
contains more than one of a particular polyatomic ion?
The parentheses are used to represent the fact that the polyatomic ion acts as a single unit.
Section 2 Review page 190
1. Determine if the following compounds are likely to have ionic or covalent bonds.
a. magnesium oxide, MgO: ionic
b. strontium choride, SrCl2: ionic
c. ozone, O3: covalent
d. methanol, CH3OH: covalent
2. Draw the structural formula for acetylene, C2H2. The atoms of acetylene bond in
order HCCH. Carbon and hydrogen atoms share two electrons, and each carbon
atom must have a total of four bonds. How many electrons do the carbon atoms
share?
The drawing shows the carbon atoms share three pairs of electrons. H C C H
3. Identify which two of the following substances will conduct electric current, and
explain why.
a. aluminum foil: will
b. sugar C12H22O11, dissolved in water: will not
c. potassium hydroxide KOH, dissolved in water: will
4. Explain why electrons are shared equally in oxygen, O2, but not in carbon
monoxide CO.
Because the atoms in a molecule of oxygen are the same they share them equally, but in
carbon and oxygen they are different
5. Predict whether a silver coin can conduct electricity. What kind of bonds does
silver have?
silver has metallic bond, it has electrons that are free to move about, so it will conduct
electricity.
6. Identify which of the bonds in calcium hydroxide, Ca(OH)2, are ionic and which
are covalent. The compound Ca and OH are ionic. The OH are covalent between oxygen
and hydrogen.
7. Does dinitrogen tetroxide, N2O4, have covalent or ionic bonds? Explain how you
reached your conclusion. It has covalent bonds because both N and O are
nonmetals.
8. An atom of the element iodine, I, has much more attraction for electrons than an
atom of strontium, Sr, does. What kind of bonds are likely to form between
atoms of the two elements? Ionic bonds will form between Sr and I atoms.
9. How are metallic bonds similar to covalent bonds? How are they different?
metallic bonds are similar because the electrons are shared between the atoms. They
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Physical Science
Chapter 6 Review Questions
are different because the electrons are free to move around in the space between the
atoms.
P 192: What determines the amounts of each ion in an ionic compound?
The number of each kind of ion in a compound is determined by whatever number of
those ions will give a charge of zero to the compound.
P 193 Practice
Write formulas for the following ionic compounds
1. Lithium oxide: Li2O
2. beryllium chloride: BeCl2
3. titanium (III) nitride: TiN
P 194 What is an empirical formula?
An empirical formula shows the simplest possible ratio of atoms present in a compound.
Section 3 Review page 196
1. Name the following ionic compounds, and specify the charge of any transition
metal cations.
a. FeI2: Iron oxide
b. MnF3: Manganese Fluoride
c. CrCl2: Chromium Chloride
d. CuS: Copper Sulfide
2. Find the charge of the cadmium cation in cadmium bromide, CdBr2. Explain
your reasoning. Cadmium will be +2 because the Bromide is -1 so to equal out it would
have to be +2.
3. Name the following covalent compounds:
a. SeO2: Selenium dioxide
b. SiL4: silicon tetriodide
c. As2O5: diarsenic pentioxide
d. P4S3: tetraphosphorus trisulfide
4. A mole of a certain compound contains 207.2 g of lead and 32.00 g of oxygen.
Without doing any calculations, tell whether a formula unit of the compound
contains more atoms of lead or more atoms of oxygen. Explain.
5. Determine the chemical formulas for the following ionic compounds:
a. Magnesium sulfate:
b. Rubidium bromide:
c. Chromium (II) floride:
d. Nickel (I) carbonate:
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Physical Science
Chapter 6 Review Questions
6. What is the empirical formula of a compound that contains 4.03 g of hydrogen per
mole, 64.14 g of sulfur per mole, and 128.00 g of oxygen per mole?
7. A sample of a compound contains 160 g of oxygen and 20.2 g of hydrogen. What
is the compound’s empirical formula?
P 199 What is the shortest chain of carbon atoms that can have more than one
arrangement?
The shortest carbon chain with more than one possible arrangement is one with four
carbon atoms; carbon chains with three or fewer carbon atoms cannot formed
branched chains
P 201 What is the relationship between a monomer and a polymer?
A polymer is a molecule that is a long chain of smaller molecules called monomers.
P 202 Why do people need carbohydrates in their diets?
You need to eat carbohydrates so your body can get the energy that it needs.
Section 4 Review page 204
1. Identify which compound is an alkane: CH2O, C6H14, or C3H4. Explain your
reasoning.
2. Determine
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